McQuay AVR User Manual

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AAF-HermanNelson Classroom Unit Ventilators

Models AVS, AVB, AVV and AVR Floor Units

Catalog UV1600

Contents

Introduction 3

AAF-HermanNelson Classroom Unit Ventilators 3 The Model AV Floor Unit 4

Features & Benefits 5

Quiet Operation With Our GentleFlo Delivery 5 The Right Amount of Fresh Air and Cooling 6 Precise Temperature and Dehumidification Control 7 Low Installation Costs 9 Low Operating Costs 10 Easy To Maintain 11 Built To Last 13

MicroTech II Controls 15

MicroTech II Controls For Superior Performance, Easy Integration 15 Control Modes and Functions 17 Advanced Control Options 19 System Components 21

Accessories 25

Wall Louvers & Grilles 25 Ventimatic™ Shutter Room Exhaust Ventilation 26 Storage Cabinets, Sink & Bubbler 27 End Panels, Filler Sections & Sub-Bases 28

Application Considerations 29

Why Classrooms Overheat 29 Meeting IAQ Requirements 31 Following ASHRAE Control Cycle II 31 Meeting ARI 840 Requirements 32 Meeting IBC Seismic Requirements 33 Face & Bypass Temperature Control 34 Modulating Valve Temperature Control 36 Coil Selection 37 DX Split Systems 38 Window Downdraft Protection 40 Digital Ready Systems 43 Field-Installed Controls By Others & Digital Ready Controls 43 Unit Installation 48 Unit Arrangements: 16-5/8" Deep 51

Unit Arrangements: 21-7/8" Deep 52

Coil Selection 55

Quick Selection Procedure 55 Coil Selection Procedure 56 Chilled Water Selection Example 58 Hot Water Heating Selection 60 Steam Heating Selection 63 Electric Heating Selection 64 Direct Expansion Cooling Coil Selection 65

Valve Selection 66

Face and Bypass End-Of-Cycle Valve Sizing & Piping 66 Modulating Valve Sizing & Piping 68 Steam Valve Sizing & Piping 70

General Data 72

AV General Data 72 Available Unit Ventilator Combinations 73 Available Coil Combinations 75

Details & Dimensions 76

Coil Connections 76 Condensate Drain Connections 79 16-5/8” (422 mm) Deep Unit Arrangements 80 21-7/8" Deep Arrangements 82 End Panels 87 Valve Dimensions 88 Wall Intake Louvers & Grilles 89 Ventimatic Shutter Assembly 90 Sink & Bubbler Cabinet 91 Filler Sections & Utility Compartment 92 Shelf Storage Cabinets 93 Finned Tube Radiation Cabinets 95

Wiring Diagrams 96

Typical MicroTech II Wiring Diagrams 96 Typical Digital Ready Wiring Diagram 99 Typical Controls By Others Wiring Diagram 100

Guide Specifications 101

AAF-HermanNelson Unit Ventilator Model AV Guide Specifications 101

The ventilation rate of AAFHermanNelson unit ventilators is certified and tested per Air Conditioning and Refrigeration Institute (ARI) Standard 840.

McQuay is a registered trademark and MicroTech II, Digital Ready, GentleFlo, ServiceTools,

Microsoft is a registered trademark and Windows is a trademark of Microsoft Corporation.

and Protocol Selectability are trademarks of McQuay International.

Introduction

AAF-HermanNelson Classroom Unit Ventilators

Low Installation Costs

New construction installations are easily accomplished with AAF-HermanNelson unit ventilators because they avoid the added cost and space required for expensive ductwork. Retrofit installations are also economical because new units fit the same space occupied by existing ones. Multiple control options—including MicroTech II controls with Protocol Selectability™, or

For more than 85 years, schools have relied on AAF-HermanNelson unit ventilators to keep classrooms comfortable. Students learn more readily in a quiet, wellventilated environment. That’s why Herman Nelson invented the unit ventilator and why we remain committed to meeting the changing requirements of schools with the highest quality products available.

We realize that keeping expenditures down is a high priority for school administrators and school boards. AAF-HermanNelson unit ventilators are inexpensive to install and operate, and they are designed and built to provide decades of trouble-free service.

Quiet Operation

AAF-HermanNelson unit ventilators are engineered and manufactured to deliver quiet, continuous comfort. We developed our GentleFlo™ air moving system to minimize operating sound levels—even as demands for more fresh air require units to operate longer and work harder.

The Right Amount of Fresh Air and Cooling

AAF-HermanNelson unit ventilators deliver required amounts of fresh air to meet ventilation requirements, and added cooling capacity to maintain consistent comfort for students and teachers. Our Economizer Operation, Demand Control Ventilation (DCV) and Part Load, Variable Air options allow you to closely match comfort requirements and reduce operating costs.

Precise Temperature and Dehumidification Control

AAF-HermanNelson unit ventilators feature precise temperature and dehumidification control to keep students and teachers comfortable while making maximum use of “free” outdoor-air cooling to reduce operating costs. They utilize a draw-thru air design that contributes to even heat transfer and uniform discharge air temperatures into the classroom. Coupled with face and bypass air control and our MicroTech passive dehumidification control strategies, they provide precise control of temperature and humidity levels.

II™ active and

Digital Ready™ features—provide easy, low cost integration into the building automation system of your choice.

Low Operating Costs

When running, AAF-HermanNelson unit ventilators can use as little electricity as two 100-watt light bulbs. They take maximum advantage of “free” cooling opportunities to reduce operating costs. During unoccupied periods and at night, units operate sparingly to conserve energy.

Easy To Maintain, Modular Design

AAF-HermanNelson Unit Ventilators are designed to provide easy access for maintenance and service personnel to all serviceable components. Most tasks are easily handled by a single person.

Built To Last

Our proven institutional design can withstand the rigors of the classroom environment. It features an extra-sturdy chassis and double-wall damper on the inside; scuffresistant finishes and tamper prevention features on the outside. In fact, many units installed over 30 years ago continue to provide quiet, reliable classroom comfort.

MicroTech II Control For Superior Performance, Easy Integration

AAF-HermanNelson unit ventilators can be equipped with MicroTech II™ unit controllers for superior performance. Factory integrated and tested controller, sensor, actuator and unit options promote quick, reliable start-up and minimize costly field commissioning. Our Protocol Selectability feature provides easy, low-cost integration into most building automation systems. Select BACnet communications to communicate control and monitoring information to your BAS, without the need for costly gateways. Unit controllers are L the optional L

, LonTalk® or Metasys® N2 Open

ONWORKS

communication module.

ONMARK

certified with

AAF-HermanNelson Model AV Unit Ventilators 3

Introduction

The Model AV Floor Unit

Our Model AV is a vertical, floor-standing unit that utilizes remotely-supplied chilled water or refrigerant for cooling, and hot water, steam or electric heat for heating. The Model AV also can be supplied as a heating/ventilating unit only or as a cooling/ventilating unit only.

The Model AV is just right for new construction and for retrofit applications. Older buildings with baseboard

Hinged Top Access Doors

Welded OnePiece Chassis

Sampling Chamber

Draw-Thru Air Flow

Quiet, Aerodynamic Fans

radiant heat or other hydronic heating systems can be easily adapted to work efficiently with Model AV units. Chilled-water or refrigerant cooling can be added to provide year-round comfort. The major features of this model are shown below and described in more detail on the following pages.

Fan Motor Out Of Airstream

MicroTech II Controls

Composite Drain Pan

Sectionalized Access Panels

Face And Bypass Damper Design

• Welded One-Piece Chassis offers

superior strength, durability, and vibration reduction.

• Unique Draw-Thru Design provides

uniform air distribution across the coil for even discharge air temperatures.

• Quiet, Aerodynamic Fans utilize

GentleFlo technology for exceptionally quiet unit operation.

• Modular Fan Section improves

balance, alignment and simplifies maintenance.

• Fan Motor Located Out Of Air

Stream and away from heating coil

reduces heat exposure to prolong life.

• Face And Bypass Damper Design

provides superior dehumidification and reduces chance of coil freeze-up

Advanced Heat Transfer Coil

• Certified Ventilation Performance

per ARI-840.

• MicroTech II Controls provide supe-

rior comfort control and easy integration into the building automation system of your choice.

• Advanced Heat Transfer Coil design

provides extra capacity.

• Sturdy Cabinet Construction

includes hidden reinforcement, a nonglare textured surface, and a tough, scuff- and mar-resistant finish to make the top sturdy enough to support maintenance personnel.

• Sectionalized Front Access Panels

provide easy access to unit interior. Panels are easily removed by a single person. Front side panels can be removed while unit is running.

Single Full-Length Air Filter

Sturdy Cabinet

• Two Hinged Top Access Doors pro-

vide easy access to motor and end bearing. Special tamper-resistant fasteners deter unauthorized access.

• Sampling Chamber for unit-mounted

sensor provides accurate sensing of room temperature.

• Indoor Room Air Damper blocks

unwanted gusts of outdoor air on windy days. Its nylon bearings are quiet and maintenance free.

• Insulated Double-Wall Outdoor Air

Damper seals tightly without twisting.

• Single Full-length Air Filter is effi-

cient and easy to replace. All air delivered to classroom is filtered.

• UL/cUL Listed

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Features & Benefits

Quiet Operation With Our GentleFlo Delivery

• Fan wheels are large, wide and rotate at a low speed to reduce fan sound levels. They are impact-resistant and carefully balanced to provide consistent performance.

• Offset, aerodynamic fan wheel blades move air efficiently (

• Precision tolerances help reduce flow and pressure turbulence, resulting in lower sound levels.

• Fan housings incorporate the latest logarithmicexpansion technology for smoother, quieter air flow (

Figure 2).

Figure 1. GentleFlo Fan Technology

Figure 1).

Expanded discharge air opening

• A large, expanded discharge opening minimizes air resistance, further lowering sound levels.

• Modular fan construction contributes to equal outlet velocities and promotes quiet operation.

• Fan shafts are of ground and polished steel to minimize deflections and provide consistent, long-term operation.

• Fan assemblies are balanced before unit assembly, then tested after assembly (and rebalanced if necessary) to provide stable, quiet operation.

Figure 2. GentleFlo Reduces Turbulence

Minimal

Offset aerodynamic blades

Logarithmic expansion housing

Precision Tolerances

AAF-HermanNelson Model AV Unit Ventilators 5

GentleFlo fan blade design

turbulence

Typical fan blade design

High turbulence

Features & Benefits

The Right Amount of Fresh Air and Cooling

AAF-HermanNelson unit ventilators deliver required amounts of fresh air to meet ventilation requirements and added cooling capacity to maintain consistent comfort for students and teachers. Our Economizer Operation, Demand Control Ventilation (DCV) and Part Load, Variable Air options allow you to match classroom comfort requirements even more closely, and reduce operating costs.

This means that you can be confident that your school is meeting ventilation standards for Indoor Air Quality and that your students are receiving adequate air to be attentive to instruction. At the same time, you are saving money in early morning hours, between classes or after hours when classrooms are heated and cooled but not always fully occupied.

Economizer Operation

It is well recognized that cooling, not heating, is the main thermal challenge in school classrooms. The typical classroom is cooled by outdoor air over half the time, even in cold climates. It is therefore essential that unit ventilators efficiently deliver outdoor air when classroom conditions call for “free” or economizer cooling.

With AAF-HermanNelson unit ventilators, you can have outdoor air whenever it is needed. Economizer operation is facilitated by the outdoor air damper, which automatically adjusts the above-minimum outside air position to provide free cooling when the outdoor air temperature is appropriate ( with MicroTech II controls, three levels of economizer control are available (see

Figure 3. Full Economizer Mode

100% Outdoor Air Into Classroom

Figure 3). On units equipped

page 17).

Part-Load Variable Air Control

Part Load Variable Air control can be used in conjunction with face and bypass damper temperature control to automatically adjust the unit ventilator fan speed based upon the room load and the room temperature. This MicroTech II control option provides higher latent cooling capabilities and quieter operation during non-peak load periods by basing indoor fan speed upon room load. Lower fan speeds in conjunction with our GentleFlo fan technology (see page

page 5) contributes to a very quiet

classroom environment.

Room-temperature PI control loops determine the speed of the fan, which varies according to the room load. It also provides a built-in delay to prevent overshooting for better comfort control. The outdoor air damper’s minimum-air position is adjusted with the fan speed to bring in a constant amount of fresh air.

Demand Control Ventilation

AAF-HermanNelson unit ventilators can be equipped to use input from a CO based on actual occupancy instead of a fixed design occupancy. This Demand Controlled Ventilation (DCV) system monitors the amount of CO outdoor air is introduced to maintain good air quality. The system is designed to achieve a target ventilation rate (e.g., 15 cfm/person) based on actual occupancy.

By using DCV to monitor the actual occupancy pattern in a room, the system can allow code-specific levels of outdoor air to be delivered when needed. Unnecessary over-ventilation is avoided during periods of low or intermittent occupancy, leading to improved energy efficiencies and cost savings.

controller to ventilate the space

so enough fresh

Face &

Bypass

Damper

Room Air

Damper

6 McQuay Catalog 1600

Filter

Outdoor Air Damper

Outdoor Air

Features & Benefits

Precise Temperature and Dehumidification Control

AAF-HermanNelson unit ventilators provide precise temperature and dehumidification control to keep students and teachers comfortable while making maximum use of “free” outdoor-air cooling to reduce operating costs. They utilize a draw-thru fan design that contributes to even heat transfer and provides uniform discharge air temperatures into the classroom. Coupled with face and bypass damper air control and/or our MicroTech

II active and passive dehumidification control strategies, they provide precise control of temperature and humidity levels under both part-load and full-load conditions.

Draw-Thru Design For Even Discharge Temperatures

The AAF-HermanNelson Draw-Thru design sets our unit ventilators apart from most competitive models. With this system, fans draw air through the entire heat transfer element ( concentrated areas of the coil element. The result is more uniform discharge air temperatures into the classroom and more efficient unit ventilator operation.

Figure 4. Draw-Thru Design Provides Even Discharge Air

Figure 4) rather than blowing it through highly

Uniform Discharge Air (Shaded)

Motor

Fans

Condenser

Ta bl e s 1 and 2 below compare the composition of the air streams through the coil and air streams bypassing the coil at various bypass air percentages for draw-thru and blow-thru unit ventilators using 450 cfm of outdoor air. At both 0% bypass air and 100% bypass air, no difference exists in the composition of the air streams. However, at all other bypass air percentages (part load), significant differences are evident.

For instance, compare the 1500 cfm draw-thru (Ta bl e 1) and blow-thru (Tab le 2) units at 70% bypass air. At this point, the draw-thru unit still has all of the outdoor air going through the coil. Meanwhile, the blow-thru unit is bypassing 70% (315 cfm) of the humid outdoor air directly into the classroom.

Table 1: AAF-Herman Nelson 1500 CFM Draw-Thru Unit

Bypass Air Stream CFM Cold Air Stream CFM

Tot al

% Bypass Air

0 1500 0 0 0 1500 1050 450

10 1500 150 150 0 1350 900 450

20 1500 300 300 0 1200 750 450

30 1500 450 450 0 1050 600 450

40 1500 600 600 0 900 450 450

50 1500 750 750 0 750 300 450

60 1500 900 900 0 600 150 450

70 1500 1050 1050 0 450 0 450

80 1500 1200 1050 150 300 0 300

90 1500 1350 1050 300 150 0 150

100 1500 1500 1050 450 0 0 0

Bypass

Total Unit CFM

From

Room

From

Outdoors

Tot al

Coil

From

Room

From

Outdoors

Table 2: 1500 CFM Blow-Thru Unit

Face & Bypass Design For Better Temperature and Humidity Control

When coupled with our draw-thru design, face and bypass damper air control offers maximum dehumidification and optimal temperature control. That’s because indoor and outdoor air streams can be separated until it is optimal to mix them.

During most part-load conditions, humid outdoor air is directed through the cold coil (coil surface below the dew point) where moisture is removed. Room air is bypassed around the coil, since it has already been dehumidified. This arrangement allows for maximum condensate removal. Humid outdoor air is not bypassed around the coil until the total amount of cooling air required is less than the total amount of fresh outdoor air required in the

% Bypass Air

0 1500 0 0 0 1500 1050 450

10 1500 150 105 45 1350 945 405

20 1500 300 210 90 1200 840 360

30 1500 450 315 135 1050 735 315

40 1500 600 600 0 900 450 450

50 1500 750 525 225 750 525

60 1500 900 630 270 600 420 180

70 1500 1050 735 315 450 315 135

80 1500 1200 840 360 300 210 90

90 1500 1350 945 405 150 105 45

100 1500 1500 1050 450 0 0 0

Bypass Air Stream CFM Cold Air Stream CFM

Tot al

Bypass

Total Unit CFM

From

Room

From

Outdoors

Tot al

Coil

From

Room

From

Outdoors

225

room.

AAF-HermanNelson Model AV Unit Ventilators 7

Features & Benefits

This illustrates that the most effective way to maintain an acceptable humidity level with a chilled-water unit ventilator system is to use a face and bypass damper, draw-thru unit.

Why Blow-Thru Designs Don’t Measure Up

Blow-thru designs cannot provide comfort like this. With blow-thru designs, the humid outside air is pre-mixed with the room air before it can go through the coil (

Figure 5). Dehumidification occurs only to the portion of the air that is directed unevenly through the cooling coil. The air that bypasses the coil is largely humid outdoor air, resulting in unconditioned air being bypassed and creating poor comfort conditions.

Figure 5. Draw-Thru Vs. Blow-Thru Design

Coil

Face &

Bypass

Damper

Room Air

Damper

Room Air

AAF-HermanNelson Draw-Thru Design

Outdoor Air Damper

Outdoor Air

With a blow-thru design the positive pressure of the fan discharge can create areas across the coil of varying temperatures and airflow. In addition, blow-thru face and bypass damper construction picks up heat by wiping the coil, creating overheating conditions. The sound level in a blow-thru design also varies based upon the position of the face and bypass damper.

Coil

Filter

RA/OA Divider

Room Air

Outdoor Air

Blow-Thru Design

See “Active Dehumidification Control (Reheat)” on page 20 for more information.

Passive Dehumidification (Optional)

On units with face and bypass damper air control and MicroTech II part-load variable air control, passive dehumidification can be used under high humidity conditions to keep classrooms comfortable. A unitmounted humidity sensor and fan speed changes are utilized to improve latent cooling by keeping the air in closer contact with the cold coil for passive dehumidification.

This occurs in the unoccupied mode as the unit operates to satisfy the unoccupied temperature and humidity set points with the outside damper closed. The face and bypass damper is placed in a minimum face position to promote high latent cooling. The unit fan continues to operate on low speed until the load is satisfied. This is very helpful in high humidity areas where high night time humidity can be absorbed in the building during off hours.

Increased Coil Freeze Protection

AAF-HermanNelson units equipped with face and bypass damper control provide extra protection from coil freeze-up. That’s because there is a constant flow of hot water through the coil, and water that is flowing typically does not freeze. Additionally, all AAF-HermanNelson units feature a double-walled, insulated outdoor air damper with airtight mohair seals to prevent unwanted coil air from entering the unit.

Furthermore, a low-temperature freezestat is factory installed on all units with hydronic coils. Its serpentine capillary tube senses temperatures across the leaving air side of the coil, allowing the unit controller to react quickly to low-temperature conditions.

Active Dehumidification (Reheat)

In high-humidity applications where valve-controlled,

Figure 6. Freezestat

Freezestat

reheat units are used, the Active Dehumidification Control (ADC) sequence should be considered. During excessive humidity conditions, a humidity sensor directs the unit to continue cooling past the room setpoint to remove excess moisture. Hydronic heat or electric heat is then used to reheat the discharge air to maintain acceptable room temperatures.

MicroTech II controls minimize the amount of reheat needed to maintain relative humidity below a preset limit.

Capillary Tube

Reheat is used only when required and in the most energy-efficient manner possible.

8 McQuay Catalog 1600

Features & Benefits

Low Installation Costs

AAF-HermanNelson unit ventilators have many features that make them economical to purchase and to install in both new construction and retrofit applications. It is this attention to detail and understanding of school applications that make them the system of choice.

Perfect For Both New & Retrofit Applications

New construction installations are easily accomplished with AAF-HermanNelson unit ventilators because they avoid the added cost and space required for expensive ductwork. Further savings can be realized because piping installations use less space than duct systems. This is important in existing buildings and also in new construction where floor-to-floor heights can be reduced, saving on overall building costs.

Retrofit installations are also economical because new units fit the same space occupied by existing ones. Using AAF-HermanNelson unit ventilators, central equipment, such as chillers, can be sized smaller using building diversity. This results in a low capital-cost system.

Built In Flexibility

AAF-HermanNelson unit ventilators include features that make them easy to set up and reconfigure as needed to meet special requirements. These features include:

• Reversible Drain Connections All units come with a composite drain pan that has drain connections on either end ( connection is also provided. The drain-side connection can be selected in the field. The direction in which the drain pan slants can also be field-modified.

Figure 7. Composite Drain Pan, Reversible Connections

• Add Cooling At A Later Date Because we recognize that some schools may wish to add cooling at a later date, even heating-only units are shipped standard with a composite drain pan.

Figure 7). A secondary, overflow drain

Secondary Overflow Drain Connection

Primary Drain

Connection

Connect Drains On Either End, Slant Pan To Either End, Can Field-Modify

• Adjustable Leg Levelers Adjustable leg levelers are furnished on the front legs of all floor units to compensate for floor irregularities (

Figure 8. Adjustable Leg Levelers

Leg Leveler

Figure 8).

• Built-in Pipe Tunnel A built-in pipe tunnel allows field crossover of hot-water or chilled-water piping, electrical conduit or refrigeration tubing (see Unit Arrangements beginning on page

51).

• Built-In Wire Race A built-in metal wire race runs from one end of the unit to the other to provide extra protection for wires and protect them from unit air.

Controls Flexibility

Multiple control options—including MicroTech II controls with our Protocol Selectability feature—provide easy, low cost integration of AAF-HermanNelson unit ventilators into the building automation system of your choice (see page 15). You can also operate these units individually or in a master-slave control configuration.

With MicroTech II controls, you select BACnet, LonTalk or Metasys and monitoring information to your BAS, without the need for costly gateways. Unit controllers are L certified with the optional L module.

Controls and communication modules can be factory provided or field-installed by others. Factory integrated and tested controller, sensor, actuator and unit options promote quick, reliable start-up and minimize costly field commissioning.

You can also use our Digital Ready option, where we factory-install and pre-wire control sensors and actuators and the controller is field-installed by others. See Ready Systems” on page 43.

N2 communications to communicate control

ONMARK

ONWORKS communication

“Digital

AAF-HermanNelson Model AV Unit Ventilators 9

Features & Benefits

Low Operating Costs

Schools consume more than 10% of the total energy expended in the United States for comfort heating and cooling of buildings. As energy costs increase, educators are placed in a difficult position: caught between rising costs, lower budgets and the requirements to raise educational standards.

Fortunately, the technology and the system exists for schools to take control of their energy expenditures while providing a comfortable environment for learning. And that system is the AAF-HermanNelson unit ventilator.

Consider these realities of school environments:

• Most heating energy in schools is expended to heat unoccupied spaces. Because lights, computers and students give off considerable heat, occupied spaces require little supplemental heat.

• The removal of heat is usually required in occupied classrooms, even when outside temperatures are moderately cold (i.e., 35-40°F).

Then consider how AAF-HermanNelson unit ventilators, located in each classroom, take advantage of these realities to lower operating costs:

• They provide individual classroom control and comfort.

• They can be cycled on when the room is occupied and

cycled off when it is not.

• They bring in fresh air from directly outside the classroom for high indoor air quality.

• During most of the school year, they use outdoor air to keep classrooms comfortable without the expense of mechanical cooling.

• They have their own air-moving device—a fan and 1/4 hp motor—which uses about as much energy as two 100-watt light bulbs. Compare this to the energy consumed by the 20-plus-hp motors used in centralized systems to cool both occupied and unoccupied spaces (at about 1 hp of energy consumed per room).

MicroTech II Control Options Further Reduce Operating Costs

Many of the MicroTech II control options available with AAF-HermanNelson unit ventilators can further reduce operating costs. For example:

• Economizer Operation Economizer operation automatically adjusts the above-minimum outside air position to provide free cooling when the outdoor air temperature is appropriate.

• Demand Control Ventilation By using CO2 levels to monitor the actual occupancy pattern in a room, the

system can allow code-specific levels of outdoor air to be delivered when needed without costly overventilation during periods of low or intermittent occupancy (

Figure 9. Energy Savings with Demand Control Ventilation

100%

20%

• Occupancy Mode Operation Units can be programmed to operate only sparingly during unoccupied periods and at night to conserve energy.

Figure 9).

Energy Savings

with DCV

Unoccupied

After Hours

DCV's fresh air for indoor air quality

6:00 8:00 10:00 12:00 2:00 4:00 6:00 8:00 10:00

School Hours

Cleaning

Unoccupied

10 McQuay Catalog 1600

Features & Benefits

Easy To Maintain

AAF-HermanNelson Unit Ventilators are designed to provide easy access for maintenance and service personnel to all serviceable components. Most maintenance tasks are easily handled by a single person.

Modular Fan Deck

The entire fan deck is easily removed as a single unit. This provides ready access to fan wheels, motors, bearings and other components for service, cleaning or repair.

The fan deck’s rotating element has one large, selfaligning, oilable end bearing and two oilable motor bearings for smoother operation. The location of these bearings at the ends of the shaft (out of the airstream) enables easy access and long life.

Figure 10. Long-life bearings

Even “permanently” lubricated motors are supplied with recommended lubrication charts calling for lubrication every seven years. Maintenance instructions of the motor manufacturer should be followed closely.

Heavy-Duty Discharge Grille

The discharge grille on the top of the unit is made from extra-strength steel bar stock, promoting long life (

Figure 11). It can be removed to facilitate cleaning of fans and fan housings. A built-in 10-degree angle provides proper air throw to blanket the room for proper air circulation and comfort.

Figure 11. Heavy-Duty Steel Discharge Grille

Easy Motor Removal

Unlike with many competitive models, the motor in AAF-HermanNelson unit ventilators is separate from the fan assembly and is located out of the airstream at the end of the fan shaft—away from the hot coil—for easier maintenance and removal. Locating the motor away from the coil ( motor life. Our direct-coupled motor and self-aligning motor mount facilitate motor change-out. The motor comes with a molex plug that fits all sizes and further simplifies removal.

Figure 12) has the added benefit of extending

Figure 12. Modular Fan Deck

Heavy-Duty Discharge Grille

Modular Fan Deck

AAF-HermanNelson Model AV Unit Ventilators 11

Motor & Bearings Located

Out Of Airstream

Features & Benefits

Tamper-Resistant Fasteners

Front panels and top access doors are held in place by tamper-resistant, positive-positioning fasteners. They are quickly removed or opened with the proper tool, but deter unauthorized access to the unit’s interior (

Figure 13).

Sectionalized Access Panels And Doors

All floor units have three separate front panels and hinged top access doors, sized for convenient handling by a single person (

Figure 13). The result is easy,

targeted access to the component that needs servicing:

• Two 12 inch-wide end panels provide easy access to piping, temperature control components and the fan switch. Unlike units with full-length front panels, these can be removed without disturbing the normal operation of the unit.

• Hinged top access doors provide easy access into the end compartments to facilitate convenient servicing of the motor and shaft bearing.

• A short, center front panel provides easy access to the filter and discharge grille.

Single-Filter Design

With AAF-HermanNelson’s single-filter design, filter change-out takes only seconds. Uneven dust loading is eliminated, which is common to units with separate filters for room and outdoor air, or that use a metal partition to separate filtering of indoor and outdoor air. The result can be longer filter life, which means less maintenance and fewer filters consumed.

Three filter types are offered:

• Single-use filters which feature Amerglas media and are designed to be used once and discarded. These are standard on all but electric heat units.

• Permanent metal filters which may be removed for cleaning and reused numerous times. These are standard on electric heat units.

• Renewable media filters, which consist of a heavyduty, painted-metal structural frame and renewable Amerglas media.

Figure 13. Easy Access With Tamper-Resistant Fasteners

Discharge Grille

Doors

Right Front Access Panel

Discharge Screen

Tamper-Resistant Fasteners

Fan Motor

Ta m pe r -

Resistant

Fasteners

Center Front Access Panel

Tamper-Resistant Fasteners

Top Access

Left Front

Access Panel

Renewable Media Filter

12 McQuay Catalog 1600

Features & Benefits

Built To Last

Our industrial-strength design provides the durability to withstand the rigors of the classroom environment. Its solid construction and rugged finish promotes continued alignment, structural strength and long-lasting beauty decades after the unit is installed. In fact, many units installed over 30 years ago continue to provide quiet, reliable classroom comfort.

Heavy Duty Frame Construction

AAF-HermanNelson’s exclusive, unitized frame (

Figure 14) is far superior to the fastener-type construction used by other manufacturers. Loosened fasteners can cause vibration, rattles and sagging panels. With unitized construction, there are no fasteners (screws or bolts) to come loose.

Other design features that promote trouble-free operation and long life include:

• A corrosion-resistant, galvanized-steel frame.

• Extra-strength, steel-bar discharge grille.

• Heavy-gauge-metal cabinet access panels and doors.

• An extra-strength pipe tunnel that stiffens the structure

while adding aerodynamic air flow within the unit.

• Hidden reinforcement that provides additional built-in

support for the top section as well as better support for the fan deck assembly.

• A rigid exterior that is strong enough to support

maintenance personnel without fear of damaging the unit.

Rugged Exterior Finish

The superior finish of the unit ventilator’s cabinets fosters long-lasting beauty as well as resistance to abuse and corrosion. We apply the very highest standards at every step of the finishing process to provide lasting quality:

• High-quality furniture steel is carefully inspected before painting. Scratches and marks that might show through are removed.

• After fabrication, the metal undergoes a five-stage cleaning and phosphatizing process to provide a good bonding surface and reduce the possibility of peeling or corrosion.

• A specially formulated, environmentally friendly, thermosetting urethane powder is applied electrostatically to the exterior panels. This film is oven-cured to provide correct chemical cross-linking and to obtain maximum scuff- and mar-resistance.

• The top of the unit is finished with a textured, non-glare and scuff-resistant, charcoal bronze electrostatic paint. End and front panels are available in a pleasing array of architectural colors.

• The Oxford brown steel kickplate is coated and baked with a thermosetting urethane powder paint to blend with floor moldings and provide years of trouble-free service.

• Each unit is painstakingly inspected before boxing, then encapsulated in a clear plastic bag, surrounded by an extra-heavy-duty cardboard box and secured to a skid to help provide damage-free shipment.

Figure 14. Heavy-Duty, Welded Chassis

Unitized Frame

Welded Construction

AAF-HermanNelson Model AV Unit Ventilators 13

Energy-Efficient Fan Motor

Features & Benefits

Durable, Energy Efficient Fan Motors

AAF-HermanNelson unit ventilators are equipped with 115/60/1 NEMA motors that feature low operating current and wattage (

Figure 15. Energy-Efficient Fan Motor

Additional features of these motors include:

• Split-capacitor (PSC) design with automatic reset and thermal-overload protection.

• No brushes, contacts or centrifugal starting switches— the most common causes of motor failure.

• A built-in, decoupled isolation system to reduce transmission of vibrations for quieter operation.

• A multi-tap, auto-transformer (Figure 16) provides multiple fan motor speed control through the speed switch. The motor is independent of supply voltage, which allows stocking of one motor (school districtwide) for various voltage applications.

Figure 16. Multi-Tap Auto-Transformer

Figure 15).

Energy Efficient NEMA Motor

Decoupled Isolation System

Additional features include:

• Face and bypass dampers have a twist-free reinforced aluminum construction for durability. Aluminum is used because it is lightweight and noncorrosive, resulting in low torque and easy movement.

• Outdoor air dampers are made of galvanized steel to inhibit corrosion, with double-wall welded construction for rigidity and encapsulated insulation (

Figure 17). Additional insulation is provided on the exterior of the outdoor air damper blade and on the outdoor air entry portion of the unit.

Figure 17. Outdoor Damper Seals Out Cold Weather

Turned Metal

Damper Blade

Turned Metal Damper Stop

Wool Mohair

End Seal

Full-Length Wool Mohair Damper

Additional Insulation

Wool Mohair End Seal

• Room air dampers are free-floating and designed to prevent intermittent gusts of cold air from blowing directly into the classroom on windy days (

Figure 18). They are constructed of aluminum with built-in rigidity. The metal forming technique that is employed resists twisting and incorporates a full-length counter weight for easy rotation. The simple principle of an area exposed to a force is used to automatically close the damper, rather than open it, when gusts of cold air occur.

Figure 18. Room Air Damper Auto-Closed By Wind Gusts

Wind Gust

Durable Damper Design

All dampers in AAF-HermanNelson Unit Ventilators use the turned-metal principle on their long closing edges (

Figure 17). Positive sealing is provided by embedding the edge into wool mohair (no metal to metal contact). There are no plastic gaskets to become brittle with time, sag with heat or age, or require a difficult slot fit to seal. Nylon damper bearings foster quiet, maintenance-free operation.

14 McQuay Catalog 1600

MicroTech II Controls

MicroTech II Controls For Superior Performance, Easy Integration

AAF-HermanNelson unit ventilators equipped with MicroTech provide superior performance and easy integration into your building automation system of choice. MicroTech II benefits include:

• Factory integrated and tested controller, sensor, actuator and unit options promote quick, reliable start-up and minimize costly field commissioning.

• High-performance features and advanced control options can quickly pay for themselves in saved energy costs and more comfortable classrooms.

• Select from three control levels: stand-alone, masterslave or network control.

• For network control applications, our Protocol Selectability feature provides easy, low-cost integration of AAF-HermanNelson unit ventilators into most building automation systems.

• Flexible BAS network communication options guard against controls obsolescence, keeping MicroTech II controls viable for the life of your AAF-HermanNelson equipment.

II unit controllers can

If a school has more than one zone, separate, remote time clocks are used to regulate each zone. In this case, the remote-mounted time clock energizes or deenergizes an external, 24-volt or 120-volt control circuit which operates the unit-mounted day/night relays in that zone.

Master-Slave Control

Designate the master and slave units and we will factory configure and install the controllers so they are set up for a local peer-to-peer network between units (leaving only the network wiring between these units to be field installed).

Slave units can be field-configured to be dependent or independent as follows:

• Dependent slave units follow the master unit completely. They are ideal for large spaces that have even loads across the space (such as some libraries).

• Independent slave units (default) use master setpoints and slave sensors. The slave follows the master unit modes, such as heat or cool, but has the flexibility to provide the conditioning required for its area within the space. Independent slave units perform better in spaces where loads vary from one area of the space to the other (such as stairwells or cafeterias).

Three Control Levels

MicroTech II unit controllers provide the flexibility to operate AAF-HermanNelson unit ventilators on any of three levels:

• As stand-alone units, with control either at the unit or from a wall sensor.

• In a master-slave relationship, where slave units follow the master unit for some or all functions.

• Controlled as part of a network using a centralized building automation system.

Stand-Alone Control

When operating in stand-alone mode, the MicroTech II controller performs complete room temperature and ventilation control. Units can be operated in occupied, unoccupied, stand-by, or bypass (tenant override) modes. Occupied/unoccupied changeover can be accomplished:

• Manually by a unit-mounted day/night switch.

• Automatically by a unit-mounted day/night time clock.

• Automatically by a remote-mounted time clock that

operates unit-mounted day/night relays.

Network Control

MicroTech II unit controllers provide easy integration into your building automation system of choice. All factoryinstalled options are handled by the unit controller. This simplifies the transmission of monitoring and setpoint data to the building automation system.

You select BACnet, LonTalk or Metasys N2 Open communications to communicate control and monitoring information to your BAS, without the need for costly gateways (see page 22). Unit controllers are LONMARK certified with the optional LONWORKS communication module.

Flexible network communication options via our Protocol Selectability feature help you avoid control obsolescence over the life of your AAF-HermanNelson equipment.

“Optional Communication Modules” on

AAF-HermanNelson Model AV Unit Ventilators 15

MicroTech II Controls

A Wide Variety of Input, Output & Alarm Data Points Available

A wide variety of data is available from AAFHermanNelson unit ventilators when equipped with MicroTech II unit controllers in a network situation. They

classroom and notify your building automation system of alarm conditions regardless of the protocol you select. See

"Table 3: Network Operation - Typical Data Points" below for a list of inputs, outputs and alarm functions available.

provide a clear picture of just what's happening in each

Table 3: Network Operation - Typical Data Points

Read/Write Attributes Read Only Attributes

• Application Mode

• Auxiliary Heat

Enable

• Compressor Enable

• Emergency Override

• Energy Hold Off

• Heat/Cool Mode

• Occupancy

Override

• Outdoor Air Humidity

• Reset Alarm

• Reset Filter Alarm

• Setpoint Offset

• Source (Water In)

Temperature

• Space CO2

• Space Humidity

• Space

Temperature

• Binary Input 1 Status

• Binary Output 1 Status

• Binary Output 2 Status

• Compressor Run Time

• Chiller Water Valve

Position

• Discharge Air Temperature

• Discharge Air Temperature Setpoint

• Effective Setpoint

• Effective Space

Temperature

• Fan Speed

• F & BP Damper

Position

• Local Setpoint

• Outdoor Air Damper

Position

• Space Fan Runtime

• Unit Ventilator

Controller State

• Water-out Temperature

• WH or CW/HW Valve

Position

Not all data points or alarms listed will be available in all unit ventilator configurations. Humidity and CO2 points require the use of optional sensors.

Read/Write

Setpoint Attributes

• Econ. IA/OA Enthalpy

Differential Setpoint

• Econ. IA/OA Temp. Differential. Setpoint

• Econ. Outdoor Air Enthalpy Setpoint

• OAD Min. Position Low-Speed Setpoint

• OAD Min. Position Med.-Speed Setpoint

• Occupied Cooling Setpoint

• Occupied Heating Setpoint

• Space CO2 Setpoint

• Space Humidity

Setpoint

• Standby Cooling Setpoint

• Unoccupied Cooling Setpoint

• Unoccupied Heating Setpoint

• UV Software Application Version

Typical Alarms

• Indoor Air Temperature Sensor

Failure

• DX Pressure Fault

• Compressor Envelope Fault

• Condensate Overflow Indication

• Indoor Air Coil DX Temperature

Sensor Failure

• Outdoor Air Temperature Sensor Failure

• Discharge Air Temperature Sensor Failure

• Outdoor Air Coil DX Temperature Sensor Failure (or)

• Water Coil DX Temperature Sensor Failure

• Water-out Temperature Sensor Failure (or)

• Water-in Temperature Sensor Failure

• Space Humidity Sensor Failure

• Outdoor Humidity Sensor Failure

• Space CO2 Sensor Failure

• Source Temperature (Water-in)

Inadequate Indication

• Change Filter Indication

16 McQuay Catalog 1600

MicroTech II Controls

Control Modes and Functions

AAF-HermanNelson unit ventilators equipped with MicroTech operate in a variety of modes based on the current situation in the room and the status of the unit ventilator. Changes in mode can be triggered manually, via network signals, by sensor readings, or by date and time. External inputs and outputs can be used to change modes, communicate data to network controls or change the functional operation of the unit.

Occupancy Modes

MicroTech II unit controllers can be set up to change modes based on room occupancy. Four different occupancy modes are provided, as described below.

Occupied Mode

This is the normal daytime operation mode. The controller maintains a room set point using the outside air capability and other functions.

Note: For non-school applications, the unit can also be

Unoccupied Mode

This is the night setback operating mode, in which the unit responds to a new room set point and cycles to maintain the condition. The fan comes on when heating or cooling is needed and runs until the load is satisfied. The outdoor air damper is closed during this mode. When a cooling load is satisfied by a refrigerant system, the compressor is de-energized and the unit ventilator indoor fan continues to run for a fixed period of time to remove coldness from the evaporator coil. This reduces the potential for low refrigerant temperatures to exist on the evaporator coil.

II unit controllers can be programmed to

configured to cycle the fan in response to the room load. In this case, the fan would normally be in the Off Mode until heating or cooling is required. The outside air damper is always closed when the fan is off. When the fan starts, the outside air damper opens to the required position, usually minimum position.

can be made in 1-minute increments from 1 minute to 240 minutes through ServiceTools™ (see network.

page 24) or a

Economizer Modes

Economizer operation is facilitated by the outdoor air damper, which automatically adjusts the above-minimum outside air position to provide free cooling when the outdoor air temperature is appropriate. Three levels of economizer control are available:

Basic Economizer Operation: The MicroTech II

controller compares the inside and outside temperatures. If the temperature comparison is satisfactory, then freeair economizer operation is used to cool the space. Reheat units also come configured with an indoor humidity sensor.

Expanded Economizer Operation: In addition to

comparing inside and outside temperatures, outdoor relative humidity is measured to calculate outside air enthalpy. If the enthalpy set point is not exceeded, and the temperature comparison is satisfactory, then free economizer operation is used to cool the space. This helps to minimize the entrance of humid outside air.

Leading-Edge Economizer Operation: The MicroTech II

controller compares both indoor and outdoor temperatures and indoor and outdoor relative humidities. Then it calculates both inside and outside air enthalpy to determine if free economizer operation can cool the space with non-humid outside air. This is a true enthalpy economizer—a first for unit ventilators.

Night Purge Mode

Under this mode, the unit is configured to purge the room space for one hour for various reasons (odor or fume removal, drying, etc.).During Night Purge the outside air damper is open full and the fan is run on high speed. No “normal” heating or cooling takes place (the emergency heat set point is maintained) and the exhaust fan, if the room is so equipped, is signaled to turn on.

Stand By Mode

In this mode, the unit maintains the occupied mode set point temperature with the outdoor air damper closed. The fan runs continuously unless it is configured to cycle in response to the load.

Bypass Mode

This is a tenant override operating mode in which the unit is placed back into the Occupied Mode for a predetermined time. The default is 120 minutes. Settings

AAF-HermanNelson Model AV Unit Ventilators 17

Freeze Prevention Mode

This mode helps protect the unit ventilator from freezing air conditions. Control functions vary depending on the type of temperature control used by the unit, as follows:

Face and bypass control units: Upon sensing a potential

freezing air temperature condition leaving the heating coil, the unit will automatically protect itself by shutting the outside air damper and opening the EOC valve. The face and bypass damper is allowed to operate normally to control the space. The fan continues to run to remove the cold air. Once accomplished, the freezestat is reset,

MicroTech II Controls

the outside air damper opens to the minimum position and the unit commences its normal mode of operation.

Valve control units: Upon sensing a potential freezing

air temperature condition leaving the heating coil, the unit will automatically protect itself by shutting the outside air damper and opening the hot water valve to a minimum of 50% (more if required to heat the room). The fan speed will be staged down to low speed and then turned off. When the freezestat is reset, the outside air damper opens to the minimum position and the fan runs at low speed for a minimum of 10 minutes. It then will stage up if needed to satisfy the room set point. This reduces the potential to overheat a room recovering from a potential freeze condition.

Note: Valve selection and coil sizing is critical for proper

operation. Face and bypass control is recommended for proper humidity and freeze protection.

Emergency Heat Mode

If the unit is left in a mode that does not normally allow heating (such as Off, Fan Only, Cool, or Night Purge) and the room temperature falls below 55°F, the unit will heat the space to above 55°F and then return to the previously set mode of operation. This mode of operation can be field configured and/or be disabled.

External Input Functions

The unit ventilator controller is provided with three (3) binary inputs that allow a single set of dry contacts to be used as a signal to it. Input signal choices are described below. Multiple units can be connected to a single set of dry contacts.

Note: Not all of the functions listed can be used at the same

time. The unit ventilator controller is provided with configuration parameters that can be adjusted to select which function will be used for these inputs where multiple functions are indicated below. For wiring examples see installation manual IM Unit Ventilator Controller.

Unoccupied Input Signal

This input signals the unit ventilator controller to go into unoccupied or occupied mode. When the contacts close, the unit ventilator controller goes into unoccupied mode; when the contacts open, it goes into occupied mode. Additional variables can affect occupancy mode and override this binary input. See

“Occupancy Modes” on

page 17.

Dewpoint/Humidity Input Signal (Optional)

This input signals the unit ventilator controller to go into active dehumidification mode. When the contacts close

747: MicroTech II

(high humidity) the controller will go into active dehumidification; when the contacts open (low humidity) it will stop active dehumidification.

Remote Shutdown Input Signal

This input signals the unit ventilator controller to go into shutdown mode. When the contacts close, the controller goes into shutdown mode; when the contacts open, it returns to normal operation.

Ventilation Lockout Input Signal

This input signals the unit ventilator controller to close the outdoor air damper. When the contacts close (ventilation lockout signal) the controller closes the outdoor damper; when the contacts open, it returns to normal outdoor damper operation.

Exhaust Interlock Input Signal

This input signals the unit ventilator controller that an exhaust fan within the space has been energized. The controller then repositions the outdoor air damper to a user-adjustable minimum position. When the contacts close (exhaust fan on signal) the controller uses the value defined by the Exhaust Interlock OA Damper Min Position Setpoint as the new minimum outdoor air damper position regardless of the indoor air fan speed. When the contacts open, it returns to normal outdoor damper operation.

External Output Functions

The unit ventilator controller is provided with three (3) binary outputs to perform the functions described below. These are relay type outputs that are intended to be used with signal level voltages only (24 VAC max).

Note: Not all of the functions listed can be used at the same

time. The unit ventilator controller is provided with configuration parameters that can be adjusted to select which function will be used for these outputs when multiple functions are indicated below. For wiring examples, see installation manual IM Unit Ventilator Controller.

Lights On/Off Signal

This relay output provides one set of NO dry contacts that can be used to signal the operation of the room lights. When the unit ventilator controller is in occupied, standby or bypass occupancy modes, the relay output will signal the lights on (contacts closed); when the controller is in unoccupied occupancy mode the relay output will signal the lights off (contacts open).

747: MicroTech II

18 McQuay Catalog 1600

MicroTech II Controls

Fault Signal

This relay output provides NO, NC, and Common connections that can be used to signal a fault condition. When a fault exists, the unit ventilator controller energizes this relay output. When the fault or faults are cleared, it de-energizes this relay output.

Exhaust Fan On/Off Signal

This relay output provides one set of NO dry contacts that can be used to signal the operation of an exhaust fan. When the outdoor air damper opens more than the Energize Exhaust Fan OA Damper Setpoint, the relay output will signal the exhaust fan on (contacts closed). When the outdoor damper closes below this setpoint, the relay output will signal the exhaust fan off (contacts open).

Auxiliary Heat Signal

This relay output provides one set of NO dry contacts that can be used to operate an auxiliary heat device. The unit ventilator controller by default is configured to operate a NO auxiliary heat device (de-energize when heat is required) such as a wet heat valve actuator with a spring setup to open upon power failure. However, the Auxiliary Heat Configuration variable can be used to set the controller to use an NC auxiliary heat device (energize when heat is required) such as electric heat.

fan operation under normal operating conditions, in conjunction with our GentleFlo fan technology (see 5page 5) contributes to a very quiet classroom envionment.

page

Demand-Controlled Ventilation (Optional)

AAF-HermanNelson unit ventilators can be equipped to use input from a CO based on actual occupancy instead of a fixed design occupancy. This Demand Controlled Ventilation (DCV) system monitors the amount of CO students and teachers so that enough fresh outdoor air is introduced to maintain good air quality. The system is designed to achieve a target ventilation rate (e.g., 15 cfm/person) based on actual occupancy.

With DCV you can be confident that your school is meeting ventilation standards for Indoor Air Quality and that your students are receiving adequate air to be attentive to instruction. At the same time, you are saving money in early morning hours, in between classes, or after hours when classrooms are heated and cooled but not always fully occupied.

controller to ventilate the space

produced by

Advanced Control Options

MicroTech II controls make possible a number of advanced control options that can quickly pay for themselves in saved energy costs and more comfortable classrooms, as described below.

Part Load Variable Air Control

Part Load Variable Air control can be used in conjunction with face and bypass damper temperature control to automatically adjust the unit ventilator fan speed based upon the room load and the room-temperature PI control loop. This MicroTech II control option provides higher latent cooling capabilities and quieter operation during non-peak load periods by basing indoor fan speed upon room load.

During low-load or normal operation (about 60% of the time) the fan will operate on low speed. When the load increases to an intermediate demand, the fan will automatically shift to the medium-speed setting. Under near-design or design-load conditions, the fan will operate on high speed. A built-in, 10-minute delay helps minimize awareness of fan speed changes. Low-speed

As Simple as a Thermostat

Demand Controlled Ventilation is easy to apply. When DCV is ordered, a CO and configured for operation. The system does the rest. If desired, the ventilation control setpoint can be adjusted through the MicroTech II Controller.

sensor is mounted on the unit

Acceptance By Codes And Standards

ASHRAE Standard 62-2004 Ventilation for Indoor Air Quality recognizes CO controlling ventilation based on occupancy. The ASHRAE standard has been referenced or adopted by most regional and local building codes. This standard references ventilation on a per-person basis.

Using CO2 control will sometimes lower the absolute amount of outside air delivered into a room but will maintain the per-person rate. For example, if a classroom is designed for 30 students, the ventilation rate is 450 cfm (30 students X 15 cfm/student). However, when there are only ten students in the classroom, the CO

control will adjust ventilation to 150 cfm (10 students

X 15 cfm/student). A minimum base ventilation rate (typically 20% of design levels) is provided when in the

based DCV as a means of

AAF-HermanNelson Model AV Unit Ventilators 19

MicroTech II Controls

occupied mode. This provides outdoor air to offset any interior source contamination while allowing for proper space pressurization.

Active Dehumidification Control (Reheat)

In high-humidity applications where valve-controlled, reheat units are used, the Active Dehumidification Control (ADC) sequence should be considered. During excessive humidity conditions, a humidity sensor directs the unit to continue cooling past the room setpoint to remove excess moisture. Hydronic heat or electric heat is then used to reheat the discharge air to maintain acceptable room temperatures.

MicroTech II controls minimize the amount of reheat needed to maintain relative humidity below a preset limit. Reheat is used only when required and in the most energy-efficient manner possible.

Active Dehumidification comes standard on units equipped with MicroTech configuration and valve-control temperature modulation. The MicroTech ADC humidity sensor is unit-mounted. It issues a signal proportional to the classroom’s humidity level (unlike humidistats which issue an open-close signal). This enables a control sequence that manages both the temperature and the relative humidity.

When the relative humidity exceeds a preset value, the modulating chilled-water valve opens fully to dehumidify the mixture of outdoor and return air entering the cooling coil. The reheat modulating water valve then opens, or electric heat is engaged, to reheat the air leaving the cooling coil, as required to maintain the classroom setpoint.

Active dehumidification starts when the indoor relative humidity exceeds the preset relative humidity upper setpoint and continues until the room humidity falls 5% below the endpoint. During active dehumidification, economizer operation is disabled (and the outdoor air damper is reset to its minimum position) unless the outdoor air temperature is below 55°F. It is maintained until dehumidification is completed. When the indoor humidity level is satisfied, the MicroTech II controller reverts to its normal sequences to satisfy the classroom temperature setpoint.

II controls, a reheat

closer contact with the cold coil for passive dehumidification.

This only occurs in the unoccupied mode as the unit operates to satisfy the humidity set point with the outside damper closed. The face and bypass damper is placed in a minimum face position to promote high latent cooling. The unit fan continues to operate on low speed until the load is satisfied. This is very helpful in high humidity areas where high night time humidity can be absorbed in the building during off hours.

DX Split System Control

On unit ventilators equipped with direct-expansion (DX) coils, the unit ventilator controller is configured to operate the compressor as secondary (mechanical) cooling when economizer cooling is available, and as primary cooling when economizer cooling is not available. Addtiional DX control features include:

Compressor Envelope: This helps protect the

compressor from adverse operating conditions that can cause damage and or shortened compressor life. It ends compressor operation if coil temperatures exceed the defined operating envelope.

Compressor Cooling Lockout: The unit ventilator

controller is configured to lock out compressor cooling when the outdoor air temperature falls below the compressor cooling lock out setpoint. Below this temperature setpoint only economizer cooling will be available.

Minimum On And Off Time: The unit ventilator controller

is provided with minimum-on and minimum-off timers to prevent adverse compressor cycling (3-minutes default).

Compressor Start Delay Variable: This variable is

intended to be adjusted as part of the start-up procedure for each unit. It is used to prevent multiple unit compressors from starting at the same time after a power failure or after an unoccupied-to-occupied changeover. Each unit should be configured at start-up with a slightly different (random) delay, or groups of units should be provided with different delays.

Passive Dehumidification Control

On units with face and bypass damper control, a chilledwater coil and MicroTech II part-load variable air control, passive dehumidification can be used under high humidity conditions to keep classrooms comfortable. A unit-mounted humidity sensor and a low fan speed are utilized to improve latent cooling by keeping the air in

20 McQuay Catalog 1600

MicroTech II Controls

System Components

The main components of the MicroTech II system are:

• The Unit Ventilator Controller (UVC)

• The Local User Interface (LUI)

• Optional plug-in network communication modules

In addition, unit ventilators equipped with MicroTech II controllers feature factory-mounted sensors and actuators for system control and feedback.

Unit Ventilator Controller

The MicroTech II UVC is a DDC, microprocessor-based controller designed to provide sophisticated comfort control of an economizer-equipped AAF-HermanNelson unit ventilator. In addition to normal operating control, it provides alarm monitoring and alarm-specific component shutdown if critical system conditions occur. Each UVC is factory wired, factory programmed and factory run-tested for the specific unit ventilator model and configuration ordered by the customer.

Figure 19. MicroTech II Control Board

Terminal Connections

Plug-In Control Module

Figure 20. User Interface Touch Pad

The User Interface has individual touch-sensitive printed circuit board mounted buttons, and comes with a built-in menu structure (Hidden Key and Password Protected) to change many of the common operating variables.

Four Operating Mode States

Four different user operating mode states can be chosen on the LUI:

Heat: Heating and economizer operation only.

Cool: Cooling and economizer operation only.

Fan Only: Fan only operation.

Auto: The unit automatically switches between heating,

cooling and economizer operation to satisfy the room load conditions. The current unit state is also displayed.

Local User Interface

A built-in LUI touch pad with digital LED Display is located in the right hand compartment below the top right access door. In addition to the Operating Mode States and Fan Functions, the Touch Pad will digitally display:

• The room set point temperature.

• The current room temperature.

• Any fault code for quick diagnostics at the unit.

Four Fan States

Four fan states are provided on all units: high, medium low and Auto speed modulation. The Auto speed function (part load, variable air) varies the fan speed automatically to meet the room load whether the unit is in heating, cooling or economizer mode.

All this is accomplished with a standard, single-speed NEMA frame motor. A built-in 10-minute delay helps minimize awareness of speed changes. During low-load or normal operation (about 60% of the time) the fan will operate at low speed. The low speed operation, along with GentleFlo fan technology, contributes to a very quiet classroom environment.

When the load increases to an intermediate demand, the fan automatically shifts to the medium speed setting. At near-design or design-load conditions the fan will operate on high speed.

With four fan states and GentleFlo fan technology, there is no need to oversize units or worry about uncomfortable conditions.

AAF-HermanNelson Model AV Unit Ventilators 21

MicroTech II Controls

Optional Communication Modules

Optional communication modules provide control and monitoring information to your building automation system without the need for costly gateways. Available communication protocols include BACnet, LonTalk and Metasys N2 Open. The communication modules for each are described below.

Figure 21. Typical 2" x 4" Communication Module

BACnet MS/TP Communication Module

This module allows the UVC to inter-operate with systems that use the BACnet (MS/TP) protocol with a conformance level of 3. It meets the requirements of the ANSI/ASHRAE 135-1995 standard for BACnet systems.

LonWorks SCC Communication Module

This module supports the LonWorks SCC (Space Comfort Communication) profile number 8500-10. Unit controllers are LonMark certified with this optional LonWorks communication module.

Metasys N2 Communication Module

This module provides N2 Open network communication capability to the UVC for communication with Johnson Metasys systems.

Figure 22. Wall-Mounted Temperature Sensors

Standard Expanded Deluxe

Standard Sensor: This sensor has no remote setpoint

adjustment capability.

Expanded Sensor: This sensor has a remote room

setpoint adjustment of ±3°F (±1.5°C) from the room setpoint established on the unit ventilator’s local user interface touch pad. Five temperature settings are provided on each side of center.

Deluxe Sensor : This sensor has a remote room setpoint

adjustment of from 54°F (12°C) to 82°F (28°C) with a midpoint setting of 68°F (20°C).

Note: McQuay does not recommend using the Deluxe Sensor

with DX systems due to its wide operating range and potential problems with the refrigerant system.

Humidity Sensors

On units equipped with humidity sensors, the UVC is configured to use a 0-100% RH, 0

VDC, capacitive humidity sensor. Humidity sensors are available as unitmounted only. The humidity sensors are used with units capable of passive or active dehumidification, or with units using an outdoor enthalpy economizer or an indoor/ outdoor enthalpy economizer.

Sensors

The UVC is configured to use passive Positive Temperature Coefficient (PTC) unit-mounted and wallmounted sensors. These sensors vary their input resistance to the UVC as the sensed temperature changes.

CO2 Sensor for Demand Controlled Ventilation

On units equipped for Demand Controlled Ventilation (DCV) the UVC is configured to use a 0-2000 PPM, 0-10 VDC, single beam absorption infrared gas sensor. CO

sensors are available as unit mounted only. An air collection probe (pitot tube and filter) is installed in the return air of the unit.

Remote Wall-Mounted Temperature Sensors

MicroTech II unit ventilators offer three choices for

Figure 23. CO2 Sensor For Demand Control Ventilation

remote wall-mounted room sensors (

Figure 22). Each has a tenant override capability and comes with an international, quick-fastening connection capability.

22 McQuay Catalog 1600

MicroTech II Controls

Figure 24. MicroTech II Sensor and Component Locations

Top V i ew

Room Humidity

Sensor (Optional)

Face & Bypass

Damper Actuator

RoomTemp

Outdoor/Return

Air Damper

Actuator

Sensor

Discharge Air Temp S e n s o r

Interface (LUI)

External Signal

Connection Plugs

Freezestat

Low Refrig Temp S n s r

Local User

Time Clock (Stand Alone Unit Option)

Tenant Override Switch

MicroTech II Unit Ventilator Controller

Communication Module (Optional)

Control Transformer

Fuse(s)

Electric Connection Box

Outdoor Air

Temp S e n s o r

Outdoor Humidity Sensor

Front View

Drainpan Condensate Overflow Sensor (Optional)

A sensor can be installed in the drain pan of the unit ventilator to sense high water levels and force the unit to discontinue cooling. This helps prevent the overflow of condensate fwhen the drain is clogged.

Actuators

Face & Bypass Damper Actuator

On units equipped with face & bypass damper control, the UVC is configured to operate a floating-point (tristate), direct-coupled, face & bypass damper actuator. To determine the modulating damper position, the controller uses a separate, factory-preset, configurable setting for each actuator's stroke time. To increase accuracy, the controller has an overdrive feature for the 0% and 100% positions and a periodic (12-hour) auto-zero PI control loop for each modulating actuator.

Figure 25. Face & Bypass Damper Actuator

CO2 Sensor

(Optional)

Main Power

On/Off Switch

Outdoor Air/Return Air Damper (OAD) Actuator

The UVC is configured to operate a floating-point (tristate) direct-coupled actuator for the outdoor air damper. This actuator provides spring-return operation upon loss of power for positive close-off of the outdoor air damper. To determine damper position, the UVC uses a separate, factory-preset, configurable setting for each actuator's stroke time. To increase actuator positioning accuracy, the UVC is provided with an overdrive feature for the 0% and 100% positions and a periodic (12- hour) auto-zero PI control loop for each modulating actuator.

Figure 26. Outdoor Air Damper Actuator

2-Position End-of-Cycle Valve Actuators (Optional)

On units equipped with 2-way or 3-way, end-of-cycle (EOC) valves, the UVC is configured to operate 2position End-Of-Cycle (EOC) valve actuators (

Figure 27). Spring return actuators are used for all End of Cycle (EOC) valves. All wet heat and heat/ cool EOC valves are normally open, and all cooling EOC valves are normally closed.

AAF-HermanNelson Model AV Unit Ventilators 23

MicroTech II Controls

Figure 27. End of Cycle Valve Actuator

Modulating Valve Actuators (Optional)

On units equipped with modulating valves, the UVC is configured to operate floating-point (tri-state) actuators for modulating 2- way and 3-way valves (

Figure 28. Modulating Valve Actuators

2-Way Valve 3-Way Valve

Figure 28).

Spring return actuators are used for all modulating valves. All wet heat and heat/ cool valves are normally open, all cooling valves are normally closed.

To determine modulating valve position the UVC uses a separate factory preset, configurable setting for each actuator's stroke time. For accuracy of actuator positioning, the UVC is provided with an overdrive feature for the 0% and 100% positions and a periodic (12-hour) auto-zero PI control loop for each modulating actuator.

Optional Time Clock For Stand-Alone Operation

As an option, stand-alone, non-slave unit ventilators can be factory-equipped with a unit-mounted, digital, 24-hour/ 7-day time clock with 20 programs ( is factory-wired to automatically place the unit into occupied or unoccupied mode based upon its schedule. Features of this clock include:

Figure 29). The clock

• Large keys with circular programming for easy schedule setup

• An LCD display

• Manual 3-way override (On/Auto/Off)

• Capacitor backup to retain program memory during

power outages.

Figure 29. Optional Time Clock

ServiceTools™

ServiceTools for MicroTech II Unit Ventilators is a CD containing software for operation on a personal computer. This software provides a visual schematic of the unit, a pictorial representation of the sequence of operation and enables the service technician to:

• Monitor equipment operation.

• Configure network communications.

• Diagnose unit operating problems.

• Download application code and configure the unit.

This software is a purchased tool for service technicians and will run on PCs with Windows 2000 (SP2), and NT4.0 (SP6) and XP (SP1) operating systems. This tool provides more capabilities than the unit’s user interface touch pad and is highly recommended for startup and servicing. (It may be required for startup and/or servicing, depending upon unit integration and other requirements.) It has no BAS functions, such as scheduling or trending, and it cannot serve as a Work Station Monitoring package.

ServiceTools comes with a service cable having two interface connections:

• A 12-pin connection to connect to the main control board.

• A 3-pin connection to connect to the optional communication modules.

98 (Second Edition),

24 McQuay Catalog 1600

Accessories

Wall Louvers & Grilles

AAF-HermanNelson wall louvers allow outdoor air to be drawn in while blending with the building architecture. They are sized to match the unit outside air opening and provide maximum air intake. Heavy-gauge, all-aluminum construction is standard, with a decorative grille optional.

Both louvers and grilles are available either painted or unpainted. When painted, a specially formulated, environmentally friendly thermosetting urethane powder is applied electrostatically and baked for long lasting beauty as well as resistance to corrosion. The paint is then oven cured to provide correct chemical crosslinking, which can provide years of service. The alloy used for louvers and grilles, AQ 5005, is suitable for color anodizing by others.

Figure 30. Intake Louvers

Horizontal Blade Louver

Vertical Blade Louver

Weep Holes

Louver Details

Louvers are available in both horizontal and vertical blade configurations (

Figure 30):

• Horizontal blade construction turns the incoming air to keep moisture from entering. Bottom weep holes drain moisture to the outside.

• Vertical-blade construction provides positive water impingement and entrapment. The bottom lip drains moisture to the outside.

Louvers can be supplied with or without flanges:

• Flanged louvers are typically used for a panel wall finish (

Figure 31).

• Unflanged louvers are typically used for recessing into a masonry wall.

A half-inch-square mesh bird screen (Figure 32) located on the leaving air side of the louver prevents birds and other small animals from entering. The screen’s strong aluminum mesh is designed to minimize air pressure drops, unlike expanded metal mesh.

Figure 32. Louver Assembly With Grille

Bird Screen

Louver

Grille

Grille Details

AAF-HermanNelson decorative intake grilles come in either painted or unpainted AQ 5005 aluminum with holes for mounting to building exteriors (

Figure 33). Their square holes are designed to match the blades of the AAF-HermanNelson louver, maximizing the air opening.

Figure 33. Decorative Intake Grille

Weep Holes

Figure 31. Flanged Louver (Indoor View)

Bird Screen

AAF-HermanNelson Model AV Unit Ventilators 25

Accessories

Ventimatic™ Shutter Room Exhaust Ventilation

Outdoor air introduced by the unit ventilator must leave the room in some way. In some states, exhaust vents are required by law or code to accomplish this. The Ventimatic shutter is a more economical solution to the problem.

The Ventimatic shutter is a continuously variable, gravityactuated room exhaust vent (

Figure 34). It operates in direct response to positive static air pressure created when ventilation air is brought into the room by the unit ventilator. It is a “one-way” shutter that opposes any flow of air into the room.

Figure 34. Ventimatic Shutter

Front (Indoor Side)Back (Outdoor Side)

The Ventimatic Shutter’s ability to exhaust only the amount of air required results in considerable energy savings. In the heating mode, the unit ventilator will be able to bring in only the required percent minimum outdoor air. Unlike systems that rely on powered exhaust, no energy will be wasted heating excess outdoor air. In the cooling mode, the unit ventilator will be able to bring in 100% outdoor air for full natural or free cooling when it is energy effective.

Since it is not powered, Ventimatic Shutter’s operation is inherently silent. Unlike other non-powered vents, it opens at an extremely low positive pressure (0.005"). Its shutter flaps are made of temperature-resistant glass fabric impregnated with silicone rubber for flexibility and long life. This fabric retains its original properties down to

-50°F.

Ventimatic Installation

The Ventimatic Shutter should be mounted on the same wall as the unit ventilator. This neutralizes the effect of wind pressure forcing excess air into the room through the unit ventilator louver. That’s because the wind pressure will also keep the Ventimatic Shutter closed and prevent room air from escaping. Since the existing room air cannot leave, excess air from the wind gust will not enter. (In contrast, a powered exhauster would “assist” the wind’s effect.) Same-wall mounting also minimizes “short circuiting” of air flow that could occur with opposite-wall mounting.

The Ventimatic Shutter is generally mounted on an AAFHermanNelson wall louver (ordered separately) which is then used for exhaust (

Figure 35). For large unit ventilators, two Ventimatic Shutters may be mounted side by side on the same wall louver to promote adequate exhaust air capacity. The size and appearance of wall louvers and grilles used for unit ventilators and for Ventimatic Shutters are identical and present an architecturally coordinated and pleasing installation.

An ideal method of integrating the Ventimatic Shutter with the unit ventilator is to locate the shutter behind a matching open-shelf or closed-shelf storage cabinet mounted next to the unit ventilator. For example, 48-inchlength wall louver can be accommodated behind a 4foot-high storage cabinet. The cabinet should be ordered with a slotted-type kick plate to provide a concealed exhaust air path to the shutter. This combination will enable a complete, integrated, energy-efficient HVAC and room exhaust system. For dimensional information, see

“Ventimatic Shutter Assembly” on page 90.

Figure 35. Ventimatic Shutter Installation

Aluminum Exterior Grille (Optional)

Aluminum Louver

Ventimatic Shutter

Louver

Two Shutter Assemblies Mounted On One Louver

Center Cover

Baffle Plate

Steel Interior Grille (Optional)

26 McQuay Catalog 1600

Accessories

Storage Cabinets, Sink & Bubbler

AAF-HermanNelson storage cabinets are designed to complement our classroom unit ventilators. They are made from heavy-gauge steel and finished with environmentally friendly, thermosetting urethane powder paint that is available in a pleasing array of matching architectural colors.

Storage Cabinets

Shelving cabinet tops are furnished with a textured, nonglare and scuff-resistant charcoal bronze electrostatic paint. Optional laminate tops are available for these cabinets and for field-supplied and installed countertops. Other features include:

• Adjustable kick plates with leg levelers are standard on all units and functional accessories. European cabinet design has adjustable leg levellers on each corner that adjust to compensate for variations in the floor.

• Adjustable-height metal shelves for flexible storage space ( tools by repositioning the four concealed shelf holding clips.

• Optional easy sliding doors with bottom glide track for good alignment ( prevents door bottom intrusion into the storage space. Optional door locks.

• Door pulls added for convenience and finished appearance.

Figure 36). Shelves can be adjusted without

Figure 37). Bottom glide track

Figure 37. Cabinet With Sliding Doors

Sink & Bubbler Cabinet

Sink & bubbler cabinets have a one-piece stainless steel top with stainless steel bowls, a raised front lip, and formed back and end splash boards ( have a choice of single or double bowls and optional door locks to conceal storage and piping. The adapter back top, when furnished, has a charcoal textured finish.

Figure 38. Cabinet With Sink And Bubbler

Figure 38). You

Figure 36. Cabinet With Shelves

AAF-HermanNelson Model AV Unit Ventilators 27

Accessories

End Panels, Filler Sections & Sub-Bases

AAF-HermanNelson end panels, filler sections and subbases can be used to match up AAF-HermanNelson unit ventilators with existing furniture or units, or with our storage, sink and bubbler cabinet offerings

End Panels

One-inch end panels are typically used to finish off stand-alone floor units. Six-inch end panels, with kick plates, can be used to provide extra space needed for piping ( wrapped in plastic and boxed to help prevent damage during construction.

Figure 39. End Panels

Figure 39). All end panels are individually

End Panel

Sub-Bases

AAF-HermanNelson sub-bases are used to provide additional height to floor unit ventilators so that they match up with the window sill or with existing cabinets (

Figure 40).

Note: Prior to 1968, unit ventilators came in 28, 30 and 34-inch

heights. The industry then standardized on the 30-inch height of the current AAF-HermanNelson unit.

Sub-bases can also be used to raise the outside air opening above floor level to reduce blockage of outside louvers and reduce louver soiling from rain splash.

They are available in 1, 2, 4, 6 and 12-inch heights with a depth of either 16-5/8" or 21-7/8". The unit ventilator’s leg levelers can also be used to level the entire unit/subbase assembly, compensating for uneven floors.

Sub-bases have an Oxford brown, baked, thermalsetting urethane powder paint finish that matches the unit’s bottom section and withstands cleaning of floors.

Figure 40. Sub-Base

Filler Sections

Filler sections can be used as spacing between cabinets, walls and unit ventilators. They are available with either laminate or painted metal tops and come in 18" and 24" lengths. They may be cut to length, with a minimum length after cutting of 3".

Each filler section includes a top, a front panel and a kick plate. Corner sections are also available which include a top, a corner post and a corner kickplate. For dimensional information and illustrations, see Sections & Utility Compartment” on page 92.

“Filler

Sub Base

28 McQuay Catalog 1600

Application Considerations

Why Classrooms Overheat

Overheated classrooms occur every day in schools in every area of the country. The most serious result is their detrimental effect on students’ ability to concentrate and learn. Research has determined that the ability to learn and retain knowledge decreases rapidly as the temperature exceeds recommendations. Overheated rooms also represent wasted fuel, resulting in excessive operating costs.

Correcting an overheating problem in an existing building is very difficult and expensive. It calls for redesign and alteration of the heating and ventilating system, necessitating considerable renovation. This potential problem should be recognized, understood and planned for when heating and ventilating systems are designed for new and existing buildings.

Schools Have Special Needs

Schools have unique heating and ventilating needs, in large part because of their variable occupancy and usage patterns. Fewer cubic feet of space is provided per student in a school building than in any other type of commercial or public building. School classrooms are typically occupied only six hours a day, five days a week, for only three-fourths of the year, with time out for vacations. All in all, this represents approximately 15% of the hours in a year that a classroom is occupied.

To understand the overheating problem in schools, one must first realize that the excess heat comes from what is commonly termed “uncontrolled heat sources.” To gain some perspective on how this affects heating and cooling decisions, let’s take a look at a typical classroom in the northern section of the midwestern United States.

Suppose we have a classroom that is 24 by 38 feet with 10-foot ceilings and 100 square feet of window area along the outside wall. At an outside temperature of 0°F and a desired room temperature of 72°F, let’s assume the normal amount of heat loss from the room to the outside is 55,000 BTUs per hour.

As the outside temperature changes, so does the amount of heat that the room loses. This is represented in

Figure 41 by Room Heat Loss Line A, which ranges from 55,000 BTUs per hour at 0°F outside air temperature to zero BTUs at 70°F. Obviously, if the heating system were the only source of heat in the classroom, the solution would be simple: The room thermostat would cause the heating system to supply exactly the amount of heat required to maintain the room at the thermostat temperature setting. In reality, the introduction of excess heat from a variety of uncontrolled

sources makes the challenge considerably more complex.

Figure 41. Heat Gain vs. Heat Loss In Occupied Classrooms

60,000

50,000

40,000

30,000

20,000

Room Heat Loss, BTU/HR

10,000

-10 0 10 20 30 40 50 60 70

As this chart illustrates, even in very cold weather an occupied classroom is more likely to require cooling than heating.

ROOM HEAT LOSS LINES

Outside Air Temperature, °F

Temperature On Room Heat Loss Line Above Which Cooling Is Always Required

10,000 BTU/HR

}

Possible Heat Gain From Sun, Direct & Reflected

8,500 BTU/HR

}

Heat Gain From Lights

7,800 BTU/HR

}

Heat Gain From Students

Heat From Students

Body heat generated by students in a classroom is one of the three primary sources of uncontrolled heat. In a typical classroom of 30 students, the amount of heat given off at all times will vary according to factors such as age, activity, gender, etc. A conservative estimate is 260 BTUs per hour per pupil. Multiply this by 30 and you get a total of 7,800 BTUs per hour added to the room by the students alone. This excess heat is noted in Figure 41 as “Heat Gain from Students.”

Heat Gain From Lights

Heat emitted by the lighting system constitutes a second uncontrolled heat source. Artificial lighting is needed in most classrooms even during daylight hours to prevent unbalanced lighting and eye strain. A typical classroom requires approximately 2,500 watts of supplemental lighting to provide properly balanced lighting. Fluorescent lights add heat to the room at the rate of 3.4 BTU per watt per hour, or a total of 8,500 BTU per hour. This extra heat is represented in

Figure 41 as “Heat Gain from

Lights.”

Add the heat gain from lighting to the 7,800 BTUs introduced by student body heat and we now have an extra 16,300 BTU/HR being introduced into the classroom by uncontrolled sources. This heat gain remains constant regardless of the outdoor air temperature.

AAF-HermanNelson Model AV Unit Ventilators 29

Application Considerations

Solar Heat Gain

The sun is a third uncontrolled source of heat. And, because it is neither positive nor constant, calculating its contribution to the overall heat gain is difficult. Solar heat gain can be the worst offender of the three in classrooms with large windows. Indirect or reflected solar radiation is substantial even on cloudy days, even in rooms with north exposure, as a result of what is termed “skyshine.”

To get an idea of the potential effect of the sun, let’s assume that the solar heat gain in our hypothetical classroom will peak at 240 BTU/HR per square foot of glass area. If we then assume a glass area of 100 square feet and at least 100 BTU/HR per square foot of glass for solar heat gain, we can calculate a very conservative estimate of 10,000 BTU/HR heat gain through windows. If we add this to the heat from the lights and body heat, total heat gain adds up to 26,300 BTU/HR from sources other than the heating and ventilating system. This is indicated in top horizontal line, which intersects Room Heat Loss Line A at approximately 37°F. This is a reasonable estimate of the maximum uncontrolled heat gain that can be received in the typical classroom from these common heat sources.

Figure 41 by the

The Analysis

From Figure 41 it is evident that, at an outside temperature of 48°F or higher, the heat given off by 30 students and classroom lighting is sufficient to cause overheating. This is true even if the classroom is occupied at night when solar heat gain is not a factor. But, since classrooms are occupied during the day, solar addition provides heat in varying amounts even in classrooms with north exposures. Consequently, the heating and ventilating system in our typical classroom must provide cooling at all times when the outdoor temperature is above 48°F and at any time during colder weather when the solar heat gain exceeds room heat loss.

If we assume an average winter temperature of approximately 33°F in the region where our typical classroom is located, we know that, half of the time, both night and day, the outside temperature will be above 33°F. However, since it is generally warmer during the day, when school is in session, the heating and ventilating system will be required to provide cooling for this classroom during much of the time that the room is occupied.

In this example, we’ve assumed that our classroom had a room heat loss of 55,000 BTU/HR at a design outdoor air temperature of 0°F (Room Heat Loss Line “A”). Bear in mind, however, that the recent trend in “energy-saving” building design often results in rooms with lower room

heat loss, as indicated by Room Heat Loss Lines “B”, “C” and “D.” At 0°F design outdoor air temperature:

• Room “B” has a room heat loss of 45,000 BTU/HR,

• Room “C” has a room heat loss of 35,000 BTU/HR,

• Room “D” has a room heat loss of 25,000 BTU/HR.

Note the lowering of the temperature above which cooling will always be required as the room heat loss decreases.

We’ve noted that cooling is always required in Classroom “A” when outdoor air temperatures exceed 48°F. In Classroom “B,” “C,” and “D” cooling is always required when outdoor temperatures exceed 44°, 36°and 23°F, respectively (

Now that we understand the reason for classrooms overheating, the solution is simple: The heating and ventilating system must provide cooling to take care of the heat given off in the classroom by uncontrolled heat sources.

Figure 41).

Cooling The Classroom

The AAF-HermanNelson Unit Ventilator has become a standard for heating and ventilating systems in schools because it provides the solution for overheating classrooms. The unit ventilator cools as well as heats. During the heating season the outdoor air temperature is nearly always below the desired room temperature. It stands to reason then that the outside air should be used to provide the cooling necessary to keep classrooms down to thermostat temperature.

The classroom unit ventilator does just that. By incorporating an automatically controlled outdoor air damper, a variable quantity of outdoor air is introduced in the classroom, metered exactly to counteract overheating. Since our problem is more one of cooling than of heating, it is evident that more than just the room heat loss must be determined to design a good heating and ventilating system. The cooling requirements should be assessed as well, and the free-cooling capacity of the equipment specified along with the heating capacity required. If this is done, the optimum learning temperature can be maintained in each classroom.

30 McQuay Catalog 1600

Application Considerations

Meeting IAQ Requirements

Good indoor air quality (IAQ), which is important in the home and at work, is no less important to students and faculty in schools. For the past several years, efforts to reduce energy costs in new school buildings have seen the use of tighter construction, sealed windows and heavier insulation. While these construction techniques have helped reduce energy costs, tightly sealed buildings, or envelopes, when combined with increased use of recirculated air, have led to a condition known as sick building syndrome.

In a poorly ventilated school building, fumes and vapors from plastics and other synthetics are often not properly exhausted, while mold, fungus, and bacteria are able to flourish. These conditions can cause various ailments, including nausea, smarting eyes, and coughing, as well as increased student absenteeism and diminished productivity.

For these reasons, the American Society of Heating, Refrigeration and Air Conditioning Engineers (ASHRAE) now recommends 15 cfm of outdoor air per pupil, and no longer endorses the practice of little or no usage of outdoor air.

AAF-HermanNelson Unit Ventilators & Ventimatic Shutters Solve The IAQ Problem

AAF-HermanNelson unit ventilators do a thorough job of maintaining a healthful and productive classroom environment through the introduction of plenty of filtered fresh air directly into the classroom. This feature, which has always been a significant factor in reducing energy costs, is now more important than ever in the promotion of a healthful environment for learning.

It should be kept in mind that a properly designed exhaust system is essential for avoiding indoor air quality problems. Simply put, if room air is not being exhausted in a prescribed fashion, fresh outside air cannot be introduced into the room. Likewise, an excessive amount of outside air will be admitted, wasting energy.

The AAF-HermanNelson Ventimatic shutter, a gravityactuated room exhaust vent, can solve both these problems. The Ventimatic shutter allows the correct amount of outdoor air to be brought into the room while maintaining a slight positive pressure in the room. This slight positive pressure, maintained during normal operation, can also help prevent the infiltration of undesirable gases into the classroom. See Shutter Room Exhaust Ventilation” on page 26.

“Ventimatic™

Following ASHRAE Control Cycle

ASHRAE Cycle II is a very economical sequence of control because only minimum amounts of outdoor air are heated and free outdoor air—natural cooling—is available to offset the large internal heat gain associated with the dense occupancy of classrooms.

AAF-HermanNelson unit ventilators are normally controlled according to ASHRAE Control Cycle II. ASHRAE control cycles apply only to heating, heatingand-ventilating and free-cooling operation. (For more information on the ASHRAE Control Cycle II sequence, see

Under ASHRAE Cycle II, the outdoor air damper is closed during warmup of the room. As the room temperature approaches the thermostat setting, the outdoor air damper opens to a predetermined minimum percentage of outside air. The heating coil capacity controller then modulates to maintain the thermostat setting.

If the room temperature rises above the thermostat setting, the heating coil is turned off and the outdoor air damper opens beyond the minimum position to maintain the thermostat setting.

EXAMPLE: For a 60°F entering air mixture temperature and 70°F room temperature, with 30°F outdoor air temperature, 25% outdoor air will produce the 60°F mixture air temperature. When the outdoor air temperature drops to 10°F, 12.5% outdoor air will produce the 60°F mixture air temperature.

Night Setback

Substantial fuel savings can be realized by operating the unit ventilator system at a reduced room setting at night and during other unoccupied periods, such as weekends and holidays. Units with steam or hot-water coils will provide convective heat during the setback period. If the space temperature falls below the setting of the unoccupied thermostat, the unit fans will be brought on to provide additional heat. Units with electric heat coils do not provide convective heat. The electric coil and the unit fans will be brought on to maintain the thermostat setting.

Typical Temperature Control Components

In general, unit ventilators require the following basic DDC electrical components in order to operate on any of the standard unit ventilator ASHRAE cycles of control. The control components listed in this section are for familiarization purposes only and should not be construed as a bill of material.

Figure 52 on page 45.)

AAF-HermanNelson Model AV Unit Ventilators 31

Application Considerations

Outdoor Air Damper Actuator

This is a modulating device under the control of the room and discharge sensors. It positions the outdoor air damper to admit the amount of outdoor air required at any given point in the control cycle. The room air damper is mechanically linked to the outdoor air damper, which permits the use of a single actuator. Electric actuators should be of the spring-return type so that the outdoor air damper closes whenever the electric power supply to the unit is interrupted.

Discharge Airstream Sensor

This device overrides the room sensor and modulates the outdoor air damper toward the closed position when the unit discharge air falls to a potentially uncomfortable temperature.

Temperature Modulation Devices

The temperature of the air entering the room is modulated using one or more of the following devices:

Face and Bypass Damper Control: A modulating

damper actuator, under control of the room sensor, positions a face and bypass damper to control the amount of air that passes through or around the unit coil.

Valve Control : A modulating valve, under control of the

room sensor, regulates the flow of steam, hot water or chilled water through the unit coil.

Electric Heat Step Control: A modulating step controller,

under control of the room sensor, steps individual electric heating elements on and off as required. Staging relays are sometimes used in lieu of a step controller.

Note: When unit ventilators containing electric heat are

ordered without controls (controls by others) the contactors and relays used for staging the electric heat are not provided. This is because the number of stages varies based on the type and manufacturer of the control devices. It is not possible to pre-engineer contactors and relays for all of these variables. The control contractor is responsible for making certain that the controls correctly control the unit’s functions.

Room Sensor

The room sensor is a temperature-sensing device that modulates the intensity of a pneumatic or electric signal to the controlled components within the unit in order to maintain the room sensor’s comfort setting. Room sensors can be mounted on the wall or within the unit in a sampling chamber.

Additional Components

Additional components may be required depending on the specific application. They include:

Sampling Chamber: This device is required whenever

the room sensor is to be mounted within the unit ventilator rather than on the wall. The sampling chamber is located behind a series of holes in the unit front panel. The sensing element of the room sensor is positioned within the sampling chamber. The unit fans draw a representative sample of room air over the sensing element at a relatively high velocity, which is necessary for rapid control response. Sampling chambers are furnished with MicroTech II controls.

Low Temperature Protection: A low temperature limit or

freezestat senses the discharge air temperature off the hydronic coil. If the temperature drops below 38°F, the unit ventilator will shut down, closing the outdoor air damper and opening the heating valve.

DX Cooling Control : This sequence switch in the

cooling control circuit energizes the condensing unit contactor on a call for mechanical cooling.

DX Cooling Low Ambient Lockout: This lockout must be

used on DX split systems to lock out the condensing unit when the outdoor air temperature is below 64°F (17.5°C). This device must be integrated into the control system so that the unit has full ventilation cooling capability during the lockout period.

DX Low Temperature Limit : This limit must be used on

DX split system cooling units to de-energize the condensing unit (compressor) when the refrigerant falls below freezing. DX units with MicroTech II controls have a factory-installed sensor on the return bend of the DX coil that provides a representative sample of the coil’s temperature.

Meeting ARI 840 Requirements

The ventilation rate of AAF-HermanNelson unit ventilators is certified and tested per Air Conditioning and Refrigeration Institute (ARI) Standard 840. Per this standard, unit ventilators with outside air ventilation and return air dampers must provide ventilation air at a rate of minimum of 80% rated standard air flow. They must also be capable of providing any combination of humidity control, circulation, heating or cooling, and filtering of air.

32 McQuay Catalog 1600

Application Considerations

Meeting IBC Seismic Requirements

AAF-HermanNelson unit ventilators can be specified, as follows, to meet International Building Code seismic requirements:

• All components included in these unit ventilators are

designed, manufactured and independently tested, rated and certified to meet the seismic compliance standards of the International Building Code.

• Components designated for use in systems that are life

safety, toxic, high hazard, combustible or flammable meet the on line, anchorage and load path requirements for life safety as defined in IBC sections

1621.1.6, 1621.3.3,1707.7.2. and IBC Commentary, Volume II, section 1621.1.6, IBC notes pertaining to the release of hazardous material.

• All components used as part of a system other than the

above meet as a minimum, all load path and anchorage standards for components as outlined in IBC section 1621.3.3 & 1707.7.2.

Figure 42. Seismic Installation

• All completed component assemblies are clearly labeled for field inspection. Seismic Compliance Labels include the manufacturer's identification, designation of certified models, definitive information describing the product's compliance characteristics, and the Independent Certifying Agency's name and report identification.

In addition to all seismic requirements for IBC Certification listed elsewhere in the project specification, submittals for these units include:

1 A Certificate of Compliance from the Independent

Certifying Agency clearly indicating that components supplied on this project are included in the component manufacturer's Certificate of Compliance.

2 Clear installation instructions including all accessory

components that are part of the overall component installation.

DETAIL

1-1/2" O.D. galvanized

Lintel (by

(4) - 3/8" galvanized nut with washer (by others), attach from inside unit end compartments. Tighten nut until steel pipe is compressed between unit and building structure or column.

(4) - 1-1/2" O.D. x (dimension X), galvanized steel pipe (by others), gives rigidity to the unit in relation with the building structure (see detail).

(4) - 3/8" diam. x (dimension Y) galvanized threaded rod (by others) - align with unit mounting holes, and set into building structure

Top mounting

hole

Building structure

NOTE: Dimensions X and Y to be determined by installing contractor based on fit up requirements of job. * A Molly or Toggle bolt may be necessary if voids in the building structure or support columns are present. 

Gasket on back of unit

AAF-HermanNelson Model AV Unit Ventilators 33

Application Considerations

Face & Bypass Temperature Control

Unit ventilators with face and bypass damper control are available for 2-pipe or 4-pipe applications. Two-pipe

unit will automatically change over to heating or cooling

as the room temperature demands. chilled/hot water installations require a system changeover from heating to cooling whenever the outdoor air temperature rises to a point that ventilation cooling can no longer offset the heat gains in the space. The reverse happens whenever heating is required. Four-pipe systems have both heating and cooling available whenever needed. With 4-pipe systems, each

Figure 43. Face & Bypass Temperature Control

Precise Environment Control

Face and bypass damper control units utilize standard

unit ventilator cycles of temperature control and bring in

up to 100% fresh outdoor air for ventilation (free) cooling

of the classroom. The bypass damper allows all air to

pass through the heating coil for fast warm-up. A portion

Morning Warm-Up/Cool-Down

Figure A shows the face and bypass damper, the room air damper, and the outdoor air damper positioned for “morning warm-up/cooldown.” During the summer the unit is cooling; in winter it is heating. When the room air temperature is above (cooling) or below (heating) the sensor setpoint, the face and bypass damper is open to the coil. At the same time, the outdoor air damper is closed and the room air damper is open. All air handled by the fan passes through the coil for maximum heating or cooling.

Maximum Heat Or Cool, Minimum Outdoor Air

Figure B shows the damper positions as the room temperature approaches the room thermostat setting. The outdoor air damper is open to the minimum setting and the room air damper closes slightly. Unit ventilators normally admit the same minimum percentage of outdoor air during the mechanical cooling cycle as during the heating cycle.

Minimum Outdoor Air, face and bypass Damper Modulation

Outdoor Air

Damper Closed

Outdoor Air

Damper

Outdoor Air

100% Room Air

Side

Coil

Minimum Outdoor Air

Side

Coil

Minimum Outdoor Air

Room SideOutdoor

Face & Bypass Damper

Room Air Damper

Room Air

Room SideOutdoor

Face & Bypass Damper

Room Air Damper

Room Air

Figure C shows normal operation. Room temperature is maintained within the operating range. Under these conditions, the outdoor air

Side

Room SideOutdoor

and room air dampers retain their same positions while the face and bypass damper modulates to provide accurate room temperature control.

Full Outdoor Air (Free Cooling)

Figure D shows the damper positions for maximum ventilation cooling. When uncontrolled heat sources tend to overheat a room (such as

Outdoor Air

Coil

Outdoor Air

Damper

100% Outdoor Air

Side

Face & Bypass Damper

Room Air Damper

Room Air

Room SideOutdoor

people, lights or sunlight), the face and bypass damper will bypass 100% of the air around the heat transfer element. The end-of-cycle valve (if furnished) will be closed to the coil. The outdoor air damper will position itself for additional outdoor air, up to 100% of the fan capacity, as required by the room cooling needs. As the outdoor air

Outdoor Air

Coil

Outdoor Air

Damper

damper opens, the room air damper closes proportionally.

34 McQuay Catalog 1600

Face & Bypass Damper

Room Air Damper Closed

Application Considerations

passes through the coil and a portion bypasses the coil when less heat is required. All air bypasses the coil when “free” cooling or no heating is required.

The superior ability of the face and bypass damper to control temperature and humidity during cooling operation is well established. Constant chilled water flow maintains the coil surface temperature at or below dew point, providing maximum dehumidification.

Ease Of System Balancing

With face and bypass damper control, the water in the system is constantly circulating, which maintains a desirable head pressure to the pumps. With fluctuating head pressure eliminated, balancing the system can enable the correct quantity of water in all circuits.

Improved Boiler Economics

In a 2-pipe system, the coil is usually selected for cooling and, during the heating season, extra coil heat transfer is available. Since the water is always being pumped with face and bypass, boiler water temperature can be modulated rather than fixed, reducing the hot water temperature to better match the heating load. This is an opportunity to reduce operating costs. By resetting the boiler hot water to 90°F and modulating upward to 140160°F for design conditions, boiler economy results in savings. Better room temperature control is available at low heating loads and the system can be quickly and easily changed over from heating to cooling or vice versa.

Since conditions of full heating or full cooling are achieved only 1-2% of the time, savings are available with today’s chillers. Load rates at changeover from heating to cooling of 100°F plus are limited and the chiller protected. McQuay chillers have this state-of-theart system. Considerable savings can be realized when you couple this cooling with today’s high-efficiency condensing boilers (which can accept 45°F entering water without damage) and with the elimination of boiler circulating pumps, mixing valves and isolation valves.

taxpayers and school officials, so limited resources can be used to support teaching.

Reduced Risk Of Coil Freeze

With face and bypass damper control, there is no change in the flow of water through the coil. Coils that have a constant flow of water—especially hot water—cannot freeze. On valve control units, water left in the heating coils after the modulating temperature control valve shuts can freeze and rupture the coil.

Additional freeze protection is afforded by AAFHermanNelson’s double-walled cold weather outdoor damper. It has encapsulated insulation and wool mohair end seals to help prevent unwanted cold air from entering the unit. This construction method further decreases the chance of coil freeze if water flow is inadvertently interrupted.

A low-temperature freezestat, factory installed on all hydronic units, significantly reduces the chance of coil freeze-up. Its wave-like configuration senses multiple locations by blanketing the leaving air side of the coil to react to possible freezing conditions.

Hot Water Reset

Automatic reset should be used to reduce the temperature of the hot water being recirculated as the outdoor air temperature rises. This should be reversed as the outdoor temperature drops. Such adjustments help prevent overheating and reduce fuel costs.

Easy Maintenance

An AAF-HermanNelson unit ventilator with face and bypass damper control is easier to maintain. It has fewer moving parts: one pump, one motorized valve, two or three small modular condensing boilers, one or two aircooled chillers, and, in each classroom, one outdoor air damper actuator, one face and bypass damper, and one fan. The system can deliver the lowest utility cost. And with their long, durable life, replacement/maintenance costs can be deferred. These low costs are desirable to

AAF-HermanNelson Model AV Unit Ventilators 35

Application Considerations

Modulating Valve Temperature Control

Modulating valve-controlled unit ventilators are an alternative to face and bypass control. All air handled by the fans passes through the coil at all times. A valvecontrolled unit ventilator is a constant-volume, variabletemperature device that delivers constant air while modulating water flow through a chilled-water coil to

and reduces the coil’s ability to remove moisture or

dehumidify. The moisture brought from outdoor air, along

with the internally generated moisture from students, can

result in unacceptable indoor humidity levels. Face and

bypass is the preferred method to maintain indoor

humidity levels and reduce damaging freezing. maintain the dry bulb (sensible) temperature in the classroom. With water flow through the coil being modulated, the surface temperature of the coil increases.

Figure 44. Modulating Valve Temperature Control

Morning Warm-Up/Cool-Down

Figure A shows the modulating valve allowing full flow through the coil and the room air damper and outdoor air damper positioned for morning warm-up/cool-down. In the summer, this is full cooling; in the winter, it is full heating. When the room temperature is above the sensor setpoint (cooling), or below the setpoint (heating), the valve opens for full flow through the coil. All air is directed through the coil(s).

Minimum Heating

Figure B shows the outdoor air damper moved to its minimum position. The modulating valve is still allowing full flow through the coil. Unit ventilators normally admit the same minimum percentage of outdoor air during the heating cycle as during the mechanical cooling cycle. All the air is directed through the coils.

Minimum Outdoor Air

Figure C shows normal operation. Room temperature is maintained by modulating the flow through the coil. The outdoor and room air dampers maintain the same positions and all air is directed through the coils.

Side

100%

Room Air

Outdoor Air

Damper Closed

Side

Mixed Air

Outdoor Air

Side

Mixed Air

Room SideOutdoor

Coil

Room Air

Room SideOutdoor

Coil

Room Air

Room SideOutdoor

Outdoor Air

Room Air

Full Outdoor Air (Free Cooling)

Figure D shows the modulating valve closed, allowing no flow through

Side

Room SideOutdoor

the coil. The outdoor damper is fully open and the room air damper is closed. The sensor setting dictates when the outdoor damper needs to begin closing. When the minimum outdoor damper position is reached, the valve needs to modulate towards the full open position. All the air is directed through the coils. (Care must be taken to ensure coils are not exposed to freezing air conditions when the modulating valve is shut or

100%

Outdoor Air

Coil

Outdoor Air

no water is flowing through coils. See “Freeze Protection” on page 37.)

36 McQuay Catalog 1600

Application Considerations

Modulating Valve Control With Hot Water Or Steam

The description of unit operation given for dampercontrolled units is correct for valve-controlled units except that references to face and bypass dampers and end-of-cycle valves should be disregarded. The capacity of the heating coil will be regulated by a modulating control valve and all air handled by the unit will pass through the heating coil at all times.

Hot Water Reset

Hot water system controls should include a provision for resetting the temperature of the supply hot water in relation to the temperature of the outdoor air. A hot water temperature of 100°-110°F, is suggested when the outdoor air temperature is 60°F. The upper limit of the hot water temperature will be dictated by the winter design conditions.

The need for hot water reset controls is not limited to applications involving unit ventilators with face and bypass control. Valve control performance will be improved as well. When the supply water temperature is far in excess of that required to offset the heat loss of the space, the smooth modulating effect of the control valve is lost. The control valve will cycle between slightly open and fully closed. The effect of heat conduction through a closed valve will also be reduced when hot water reset is used.

Freeze Protection

System freeze protection is an important consideration on units utilizing hydronic coils. On valve-controlled units, water left in the heating or cooling coils and exposed to freezing outdoor air after the modulating valve shuts can freeze and rupture the coil. Flowing water will not freeze. In addition, it is very important to correctly size the modulating control valve and control the supply water temperature to provide constant water flow. If this situation cannot be guaranteed, an antifreeze solution must be employed to reduce the possibility of coil freeze.

Coil Selection

An extensive choice of coil offerings means that, with AAF-HermanNelson unit ventilators, room conditions can be met using almost any cooling or heating source. All coils are located safely beneath the fans and are designed for draw-thru air flow. All coils have their own unshared fin surfaces (some manufacturers use a continuous fin surface, sacrificing proper heat transfer). The result is maximum efficiency of heat transfer, which promotes comfort and reduces operating costs.

An air break between coils in all AAF-HermanNelson units is used to enhance decoupling of heat transfer surfaces—providing full capacity output, comfort and reduced operating costs.

All water, steam and direct expansion (DX) coils are constructed of aluminum fins with a formed, integral spacing collar. The fins are mechanically bonded to the seamless copper tubes by expansion of the tubes after assembly. Fins are rippled or embossed for strength and increased heat transfer surface. Coils and units are ARI capacity rated.

High-Quality Water Coils

AAF-HermanNelson water coils rely on advanced heat transfer to provide extra cooling capacity for today’s increased ventilation requirements. Tuned internal water flow and a balanced header design, together with additional surface area in the air stream, increase heat transfer to satisfy the increased need for dehumidification.

A manual air vent is located on the top of the coil header of all floor hydronic coils. ( be purged from the coil during field start-up or for maintenance.

A manual drain plug (Figure 45) is provided at the bottom of the coil header for coil drainage. Some competitors may not provide for drainage of coils.

Figure 45. Manual Air Vent & Drain Plug

Air Vent

Figure 45). This allows air to

Drain Plug

AAF-HermanNelson Model AV Unit Ventilators 37

Application Considerations

Long Lasting Electric Heating Coils

With our draw-thru design, electric coils are directly exposed to the air stream. They come with a built-in switch to de-energize the coil when the center front panel is removed. A unit-mounted disconnect switch is included. A continuous electric sensory element for high temperature is not required because the air is drawn smoothly and evenly across the coils, prolonging life. (Blow-thru designs use cal rods inserted into the tube of a fin tube coil that results in reduced heat transfer. The constant movement of the electric heating cal rod within the tube shortens life.)

Even Distribution Steam Coils With Vacuum Breakers

Steam distribution coils provide even distribution of steam and even discharge air temperatures. A vacuum breaker relieves the vacuum in the steam coil to allow drainage of condensate. This eliminates water hammer and greatly reduces the possibility of coil freeze-up.

DX Split Systems

AAF-HermanNelson unit ventilators are available with direct expansion (DX) cooling coils that are equipped with thermal expansion valves. Unit ventilators with DX coils operate as a system with most properly sized R22 condensing units. In most classroom applications, if the unit ventilator and the condensing unit are sized properly, the application should fulfill its design expectations.

The proper selection of a DX split system unit ventilator for a classroom requires special considerations. This is due to the high amount of outdoor air ventilation required and to the occupied and unoccupied cooling requirements. Because of the high number of occupants in classrooms, cooling is required even when the outside air temperature is very mild. With mild ambient conditions, down to 55°F, the system can create colder discharge air temperatures than desired and can even trip the DX low temperature limit on the unit.

Condensing Unit Selection

Proper sizing of the field-supplied condensing units is important for trouble-free operation. An oversized condensing unit can reduce performance and cause operational problems, such as:

• Rapid temperature pull down, causing short cycling

and potential compressor damage.

• Poor temperature and humidity control.

• Low saturated evaporator coil conditions.

• Low discharge air temperatures.

If the DX system is oversized for the room loads the

compressor will have short run times. When rooms are

occupied, unit ventilators provide outdoor air to the space

continuously. In humid areas, the outdoor air is laden

with moisture. The room thermostat responds to the

room sensible temperature. With short compressor run

times (oversized condition) the system is unable to

extract the moisture and the humidity level builds,

sometimes exceeding 60 percent.

To properly size the unit ventilator, determine the cooling

load based on May and September conditions at 1 pm

when the classroom is occupied. Do not select units for

July or August, after 3 pm, or when the classroom is

unoccupied. Select a properly sized unit based on the

calculated cooling load, ambient air temperature and

enter air temperature to the coil. If the calculated cooling

load falls between two unit sizes, select the smaller of

the two units to minimize the potential problems seen

with oversized units.

A general rule for DX unit sizing is 400 cfm per ton of

cooling capacity. If the 400 cfm per ton criteria is

followed, most problems can be avoided. Review the

design selection for the system and a typical low ambient

condition to determine if the suction temperatures are

below an acceptable level.

Ta bl e 4 shows the recommended condensing unit size,

based on nominal tons, for each size unit ventilator. The

Table is based on 400 plus cfm per ton for high-speed

operation, at design conditions. If you anticipate a lower-

speed DX cooling operation, additional static pressure,

or lower outdoor ambient temperature operation, a

smaller condensing unit should be considered.

Table 4: Condensing Unit Size Selection

Unit Vent

Model

SO7 750 1-1/2

S10 1000 2-1/2

S13 1250 3

S15 1500 3-1/2

Unit Vent

CFM Nominal

Condensing Unit Size

Tons Nominal

Control Considerations

Most unit ventilators for classroom applications require

compressorized cooling below 75-80°F outdoor ambient

due to internal student, equipment and solar loads. For

effective system operation and correct thermal

expansion valve operation at these conditions,

condensing unit head pressure control is required. A hot

gas bypass system or an evaporator minimum pressure

38 McQuay Catalog 1600

Application Considerations

regulator may also be required to maintain suction pressure.

The unit ventilator incorporates provisions for wiring to the contactor in the condensing unit. A 5-minute delay relay is included to reduce compressor cycling. On Digital Ready and Controls By Others units, a DX low limit is included to help protect against abnormally low evaporator coil temperatures caused by unit ventilator motor failure, blocked air filters, or other restrictions to airflow.

When MicroTech II unit ventilator controls are provided, the controller operates the condensing unit contactor, as needed, to provide cooling when required. The compressor envelope will disable compressor operation when a low limit condition exists.

When controls are not provided by AAF-HermanNelson, the normally closed contacts of the DX low limit should be electrically connected (following all appropriate codes) to disable the compressor when contacts open. Controls must be designed to keep the unit ventilator fan running when the compressor is on, so that the face and bypass damper is full face for compressorized cooling operation and other system safeties are provided and integrated into the system controls correctly.

When a DX coil is used for the main source of cooling, the outdoor condensing unit will be cycled on and off as required to maintain the room temperature.

A low temperature thermostat control is inserted into the DX coil to prevent frosting. When tripped, the outdoor condensing unit is locked out and the indoor unit ventilator fan continues to run. When the DX coil temperature rises above the trip set point, the outdoor condensing unit will be allowed to operate.

The outdoor condensing unit is also locked out based on outside air temperature. If the outside air is below the DX outside air low limit the outdoor condensing unit is locked out and cooling is provided by the economizer of the unit ventilator.

wired to the fan control switch to de-energize the 24-volt circuit when the switch is in the off position. The condensing unit must be controlled by the same room sensor that controls the unit ventilator.

The temperature control contractor must field supply a low-ambient thermostat in the 24-volt circuit to prevent operation of the condensing unit when the outdoor air temperature is below 60°F. Wire this device into the temperature controls in such a manner that, when the low ambient thermostat opens at 60°F, the unit ventilator is returned to the heating-only mode with full ventilation cooling capabilities.

Typical System Wiring And Piping

General system wiring and piping for a DX system are shown in Figures see AAF-HermanNelson Unit Ventilator Installation Manual IM 817.

Figure 46. Typical DX System Wiring

Roof Surface

Pad Or Support 4-6 inch

Minimum (By Others)

Unit Ventilator

Floor Line 24 Volt Transformer

46 and 47. For additional information,

Fused Disconnect Switch (By Others

24 Volt (2 Wire)

Interconnecting Control

Wiring (14 AWG)

(By Others)

Separate Electrical Service 208/230-60-1 208/230-60-3 440/480-60--3

Condensing Unit Installation

The condensing unit must not be located more than 30 feet above the unit ventilator and should be located at least 24 inches from a wall or other obstruction to provide unrestricted airflow and to allow for service access. Since condenser discharge air is vertically directed, do not allow any obstruction within 6 feet (measured vertically) from the top of the condensing unit.

Control circuit power, located in the unit ventilator right end compartment, is obtained from a 24-volt transformer furnished by AAF-HermanNelson. The transformer is

AAF-HermanNelson Model AV Unit Ventilators 39

Application Considerations

Figure 47. Typical DX System PIping

Sweat

Outdoor

Condensing Unit

Roof Surface

Pad Or Support 4-6 inch

Minimum (By Others)

Refrigeration Tubing

(By Others) See Dimensional

Data For Correct Sizes

Unit Ventilator

Sweat Connections

Floor Lines

Connections

Sleeve & Flashing (By Others)

Nominal cooling capacities are based on 20 feet (one way) of refrigerant tubing between the unit ventilator and the condensing unit. Cooling capacities will be reduced by 20 BTU for each foot in excess of 20 feet. Refrigerant tubing must not exceed 90 feet.

Systems using refrigerant lines longer than 20 feet between the unit ventilator and condensing unit may experience a slight capacity reduction and require crankcase heaters, additional refrigerant oil and refrigerant, and special piping considerations. Clean, refrigerant grade tubing must be used and precautions taken to prevent oxidation and scale formation inside the tubing during brazing. Adequate system isolation valves are required. A filter drier and sight glass are recommended. For specific recommendations on suction and liquid line sizes, routing and length limits, follow the condensing unit manufacturer’s recommendations and the ASHRAE Guide.

Most condensing units are pre-charged with refrigerant (R-22) for a nominal length of tubing. It may be necessary to add additional charge. The system, including the unit ventilator coil, must be leak tested and evacuated before charging.

Proper refrigerant charge is critical for optimum system operation. The system is correctly charged when superheat and sub-cooling are within limits after the system has been operating at a stable condition for approximately 15 to 20 minutes. At 80°/67° F indoor conditions and 95°F outdoor ambient, suction superheat should be 5° to 7°F and sub-cooling at the condensing unit 15° to 16°F. For additional details, refer to the condensing unit manufacturer’s start-up documents.

Window Downdraft Protection

Downdrafts can be generated in classrooms with

relatively large windows during prolonged periods of cold

outside temperatures. For comfort during such

conditions, provide some form of downdraft protection.

Window downdraft protection is recommended for

classrooms where the following conditions exist:

• Window area exceeds 40% of the total outside wall area.

• Single-pane glass is used.

• Outside temperatures are below 35°F for a significant

portion of the occupied period.

The need for window downdraft protection will not always be so clear cut. Where uncertainty exists, a further check can be made by calculating the window heat loss at an outdoor temperature of 35°F. If estimated window heat loss exceeds 250 BTUH/ft, window downdraft protection is recommended. If estimated window heat loss is less than 250 BTUH/ft, the need for downdraft protection is marginal but should not be arbitrarily dismissed.

DraftStop Downdraft Protection

The AAF-HermanNelson DraftStop System is one of the best systems available to address the downdraft problem. This unique system intercepts falling cold air at the window sill level and recirculates it back to the unit ventilator ( through the room air damper and becomes part of the normal air circulation pattern. This is accomplished by blocking the return air grille at the front of the unit ventilator to cause the return air to be drawn in through the ends of the unit.

Our DraftStop system can be employed even in marginal applications to provide occupant comfort without the material installation and operating costs associated with auxiliary radiation.

Figure 48. DraftStop Window Downdraft Protection

Figure 48). It then enters the unit’s air stream

Cold Air Falling From Window

40 McQuay Catalog 1600

Application Considerations

DraftStop wall enclosures or cabinets are fitted to the ends of the unit ventilator so that there is a continuous, elongated return air grille located beneath the windows. These cabinets have a built-in 3" or 5-13/16" cavity between the rear of the cabinet and the wall. This forms the return air path to the unit ventilator.

Cool air from the windows is drawn into the plenum before it is allowed to reach the occupants. Either a steel bar inlet grille or a stamped inlet grille is fitted to the rear of the cabinet, flush with the cabinet top. Consult

Ta bl e 5 for recommended minimum and maximum DraftStop grille lengths. Note that the maximum lengths are based on maintaining optimum velocity through the DraftStop

Figure 49. How DraftStop Works

Morning Warmup

During this period, no outdoor air is admitted. The cold air from the windows flows into the DraftStop slot and is drawn toward the unit ventilator. This air enters the unit through the room air damper, passes through the heating element and is discharged into the room.

grille. If the maximum lengths are exceeded, the system will remain operational, but efficiency will be reduced.

Table 5: DraftStop Grille Lengths

20" High DraftStop

Unit

Model

S07313322

S10418430

S13522536

S15625642

With Enclosure

Minimum

Length Each

Side

Maximum

Length Each

Side

Unit Discharge

24" High Draftstop Wall

Enclosure Or Storage Cabinet

Minimum

Length Each

Side

Down Drafts

Maximum

Length Each

Side

Normal Operation

During much of the day, the unit ventilator circulates a mixture of outdoor air and room air, proportioned to maintain thermal comfort in the classroom. The return air continues to be drawn off the windows, providing the DraftStop action. We now see the impact of the optional Ventimatic gravity exhaust, concealed behind the cabinets. It allows air to be expelled to the outdoors. This prevents excessive room pressurization, which would interfere with the ventilation cooling capability of the unit. This exhaust action also enhances the DraftStop effect since the air to be exhausted is forced into the DraftStop slot at sill level.

Maximum Ventilation Cooling

During these periods, the unit ventilator will operate with the outdoor air damper fully open. In this mode, there will be little or no return air to the unit and little or no DraftStop action. The unit ventilator will not operate at maximum ventilation cooling when the outdoor temperature is low enough to create cold window downdraft conditions. Therefore, the lack of DraftStop action is of no consequence. The optional Ventimatic exhaust continues to provide an effective means of relieving the room of excess pressure.

Outdoor Air

Unit Ventilator

Unit Discharge

Unit Ventilator

Unit Discharge

Unit Ventilator

Down Drafts

Optional Ventimatic Exhaust

AAF-HermanNelson Model AV Unit Ventilators 41

Application Considerations

DraftStop Cabinets

In applications where AAF-HermanNelson cabinets are included as part of the classroom equipment, the DraftStop feature can be added at no increase in material cost. Installation labor cost would also be the same. Both shelf cabinets (16-5/8" or 21-7/8" deep) and sink-bubbler cabinets (21-7/8" deep) are available in the DraftStop configuration. See

“Shelf Storage Cabinets” on

page 93.

Filler sections are available to complete the installation. However, they do not have inlet grilles and their use under windows should be held to a minimum.

DraftStop Wall Enclosures

Wall enclosures are used to form the return air path to the unit ventilator when DraftStop cabinets are not used. They can be 14", 20" or 24" high and are available in 1´ through 8´ lengths, in 6" increments. Accessories, such as wall trims and end caps, are available to complete the installation.

DraftStop Installation

Normal installation measures should be followed when using DraftStop enclosures or DraftStop cabinets. If the grille length limitations are adhered to and the DraftStop grille dampers are adjusted to achieve a uniform velocity in the 150 FPM to 500 FPM range, the system will be functional. Radiation elements can be installed behind storage cabinets or in separate wall-hung enclosures.

A manually adjustable damper is located beneath each section of the DraftStop grille. This damper is provided so that a uniform air velocity can be achieved throughout the length of the grille. A simple adjustment is made once by the installer during the final stage of installation.

Figure 50. Finned Radiation & Draftstop Enclosures

Finned Radiation

DraftStop

Finned Radiation Application Considerations

There will be many periods during the heating season when window downdraft protection is required even though the unit ventilator is no longer adding heat to the space. In fact, the unit ventilator will most likely be attempting to cool the space with outside air due to the heating effects of occupants, solar load and lights. This presents an obvious control dilemma when using radiation as window downdraft protection.

Auxiliary radiation is normally controlled so that the radiation is turned off whenever the unit ventilator heating element is off (

Figure 51). This control sequence is required to prevent the costly addition of heat not required by the space. It is also used to prevent serious overheating problems that can occur if the radiation capacity exceeds the ventilation cooling capability of the unit. However, this is a compromise solution.

Figure 51. Typical Finned Radiation Piping

Finned Radiation Downdraft Protection

Finned radiation downdraft control is available for those who prefer it. Components are made of furniture-quality steel and designed to complement the unit ventilator

Aux Radiation

styling. It is particularly appropriate for a building with very large expanses of window where the DraftStop

*Not Required With Face & Bypass Control

system is not used, and for use in other parts of the building. For more information on finned radiation system components available and dimensions, see

“Finned Tube

Radiation Cabinets” on page 95.

Cold window drafts can definitely exist even when no further heat is required in the room. In fact, a well-heated room can accentuate the draft problem due to the larger difference between room air and window draft temperatures. To conform to the above control sequence, steam or hot-water radiation will require an additional field-installed control valve (see

“Auxiliary Heat Signal” on page 19 for auxiliary

heat control function and setup).

42 McQuay Catalog 1600

UV Control Valve*

UV Coil

Aux Radiation

Radiator Control Valve

Application Considerations

Digital Ready Systems

For unit ventilator applications where controls are to be supplied by others, specifying a Digital Ready system can greatly simplify control installation.

Digital Ready systems come with a factory-installed, prewired package of selected Direct Digital Control (DDC) components. This greatly facilitates the field hook up of a DDC unit ventilator controller that is compatible with these components and that is capable of providing the standard ASHRAE II cycle (see Control Cycle II” on page 31).

Note: It is the responsibility of the control supplier to ensure the

controls operate correctly and protect the unit.

Digital Ready systems include the following components, which are factory wired and powered:

1 A non-fused power interrupt switch.

2 Hot line(s) for the fan motor and controls protected by

factor- installed cartridge type fuse(s).

3 A three-speed HIGH-MEDIUM-LOW-OFF motor fan

speed switch.

4 A 75 VA, 24-volt NEC Class 2 transformer for the 24-

volt power supply.

5 Three 10-pole, Europa-type, 16 awg terminal strips

rated for 10 amps at 300 volts with nickel-plated connectors and zinc-plated clamping screws.

6 Approximately 8" x 21" (203mm x 533mm) of space

provided in the unit ventilator’s left end compartment for unit ventilator controller mounting (by others).

7 Interface to the fan motor start/stop relay (R4).

8 Interface to a factory-installed low-air-temperature-

limit freezestat (T6). The freezestat cuts out below 38±2°F and automatically resets above 45±2 °F. It responds when any 15% of the capillary length senses these temperatures. And, it is wired so that upon T6 cut out, the outside air damper closes, the hot water valve opens and the 24 volt power supply to the terminal strip (T6 Sig) is interrupted.

9 Discharge air temperature sensors: 10 K ohm NTC

(Negative Temperature Coefficient) and 1 K ohm PTC (Positive Temperature Coefficient) located on the second fan housing from the right side of the unit.

10 Room temperature sensors: 10K ohm (NTC) and

1Kohm (PTC).

11 Outdoor air temperature sensors: 10K ohm (NTC) and

1Kohm (PTC).

12 A direct-coupled, proportional-control (2 to 10 VDC or

4 to 20 mA) outdoor air/return air damper actuator with spring return.

“Following ASHRAE

13 A direct-coupled, proportional-control (2 to 10 VDC or

4 to 20 mA) face and bypass damper actuator without spring return.

14 Interface from the terminal board with one or two end-

of-cycle DDC valves with spring return actuators (by others) providing 24-volt power. Open/shut signal from unit ventilator controller (by others).

15 A 24-volt power wiring harness from the right to left-

hand end compartment of the unit, through the built-in metal wire raceway, and terminating at three terminal blocks.

16 DX low-limit designed to protect against abnormally

low evaporator coil temperatures (DX units only).

Note: See “Required Control Sequences” on page 44 for

control sequences that should be incorporated for equipment protection and occupant comfort.

Field-Installed Controls By Others & Digital Ready Controls

There are many advantages to having the basic temperature controls in AAF-HermanNelson units be MicroTech II and factory-installed in the unit ventilator prior to shipment (see Superior Performance, Easy Integration” on page 15). However, factory installation of controls cannot always be achieved. For example, sometimes the specified controls are nonstandard and as such deviate from the pre-engineered DDC control packages available.

A particular school system may have a preferred temperature control supplier that is unable to interface with standard unit ventilator controls or may decide to field-install them. In such cases, we will ship the unit without any temperature controls. It is the responsibility of the automatic temperature control supplier to provide a control package specifically for installation in the AAFHermanNelson unit ventilator.

The responsibility for proper control operation and application always rests with the Automatic Temperature Control (ATC) contractor regardless of whether the controls are factory installed or field installed.

The effect of misapplied or improperly installed controls can go beyond unacceptable or poor temperature control: unit ventilator components may be damaged by control misapplication. Brief examples of this include:

• Frozen hydronic coils due to improper or lack of freeze protection and/or incorrect control cycle (failure to close outdoor air damper and open the hot water temperature control valve during night cycle, full

“MicroTech II Controls For

AAF-HermanNelson Model AV Unit Ventilators 43

Application Considerations

shutoff of water through a coil exposed to freezing air, etc.)

• Compressor failures where condensing units are permitted to operate at low ambient conditions or without room air fan operation for prolonged periods.

• Failure of AAF-HermanNelson furnished protective devices due to excessive recycling caused by improper control cycle.

AAF-HermanNelson disclaims all responsibility for any unit component failure that may occur due to improper temperature control application or installation.

The following presents information on specific factoryprovided equipment protective devices and their suggested use by others in non-MicroTech sequences. The Automatic Temperature Control supplier is responsible for correct operation and unit protection.

II control

ASHRAE Cycle II

We strongly recommend that ASHRAE Cycle II be implemented with all unit ventilators using controls by others. ASHRAE Cycle II is a very economical sequence since only the minimum amount of outside air is conditioned and free natural cooling is available. See Figure 52:“ASHRAE Cycle II Operation” on page 45.

During warm-up (any classroom temperature 3°F or more below heating setpoint), the outdoor air damper is closed and the unit conditions only room air. As room temperature approaches the heating setpoint the outdoor air damper opens to a position that permits a predetermined minimum amount of outside air to be drawn in. Unit capacity is then controlled as needed to maintain room setpoints. If room temperature rises above room cooling setpoint, and the outside air is adequate for economizer cooling, then the outdoor air damper may open above the minimum position to provide economizer cooling.

ASHRAE Cycle II requires that a minimum of three temperature measurements be made:

1 Classroom temperature.

2 Unit discharge air temperature.

3 Outdoor air temperature.

Additionally, the control sequence should incorporate a Discharge Air Low Limit function which requires a discharge air temperature sensor and can override classroom temperature control in order to maintain a discharge air temperature setpoint of 55°F.

When the discharge air temperature drops below 55°F, the discharge-air low-limit function will disable cooling (if enabled) and modulate the unit’s heating capability as

needed to maintain the 55°F discharge-air setpoint regardless of room temperature.

If the unit’s heating capability reaches 100%, then the discharge air low-limit function will modulate the outdoor air damper toward closed to maintain the 55°F discharge air setpoint. Outdoor air temperature is used to determine when to use economizer as a first stage of cooling, and when to use mechanical or hydronic cooling as the first stage of cooling.

Required Control Sequences

When using controls by others or digital-ready units, the following control sequences should be incorporated for equipment protection, and occupant comfort. Not including them may void the unit warranty. It is the responsibility of the Automatic Temperature Control supplier to ensure the controls operate correctly and protect the unit.

DX Low Temperature Limit Sequence

Each of the following units comes with a factory-installed DX Low Temperature Limit switch:

• DX Cooling With Electric Heat

• DX Cooling Only

• DX Cooling With Steam Or Hot Water Heat Using

Valve Control

• DX Cooling With Steam Or Hot Water Heat Using Face And Bypass Damper Control

Its function is to temporarily de-energize the DX system when the DX coil becomes too cold. This switch has a cut-out setting of no less than 28±3°F and a cut-in temperature setting of approximately 48±3°F. When the switch cuts out due to low temperatures the compressor (condensing unit) must be de-energized until the switch cuts in (coil has warmed up).

The condensing unit should have its own high-pressure safety sequence or head pressure control and a Low Ambient Temperature Lockout feature which prevents DX cooling operation when the outside air temperature drops below 60°F. Cooling should be provided via an outdoor air damper economizer function when the outside air temperature drops below 60°F.

DX Cooling Sequence with Steam or Hot Water Heat and face and bypass Damper Control

For this configuration, a heating End-Of-Cycle valve must be used so that hydronic heat can be switched off when DX cooling is required. Improper system operation will result if this valve is not provided. When cooling is required, the controls must force the face and bypass

44 McQuay Catalog 1600

Application Considerations

Figure 52. ASHRAE Cycle II Operation

Typical Outdoor Air Damper Operation

A Outdoor air damper closed.

B Outdoor air damper at minimum position.

C Economizer function is increasing the outdoor air

damper position.

Note: If outdoor air temperature is not adequate for free

cooling, secondary mechanical cooling can be used in place of economizer cooling. A low discharge air function is used to help maintain comfort and provide additional equipment protection by preventing the discharge air from falling too low (typically 55°F), and may force the outdoor air damper toward closed to maintain the discharge air temperature regardless of room temperature.)

D Damper is at full open.

Typical Heating Operation

E Heating capability is closed (or off).

F Heating begins to modulate (or on).

G Heating capability has reached 100%.

damper to a full-face position prior to starting DX cooling. See

“DX Split Systems” on page 38 for additional

controls required for DX operation.

Chilled-Water Cooling Sequence with face and bypass Damper Control and Electric Heat

When heating is required, the controls must force the face and bypass damper to a full-face position prior to energizing the electric heaters.

End-Of-Cycle (EOC) Valve Operation

The intended purpose of an EOC valve is to reduce the chances of conductive radiant overheating or overcooling which can occur when the face and bypass damper is in the full bypass position (i.e., no heating or cooling required).

A heating EOC valve must be used on units with DX cooling coupled with steam or hot water heat and face

Typical Mechanical Cooling Operation

H Mechanical cooling (hydronic or DX) is closed (or

off).

I Mechanical cooling (hydronic or DX) begins to

modulate (or on). (Note: If economizer cooling is available, then mechanical cooling should be used as a second stage and therefore delayed until the outside air damper reaches near full open.)

J Mechanical cooling (hydronic or DX) has reached

100%.

and bypass damper temperature control. It is optional for the remaining models. However, it is strongly recommended that heating or heat/cool EOC valves be used on all face and bypass units with heating capability to prevent overheating.

Heat/Cool EOC Valve (2-pipe)

For units with chilled-water cooling and hot-water heating (2 pipe) and face and bypass damper control:

• The heat/cool EOC valve should be a normally open, spring return (open), two position valve.

• A water-in temperature sensor should be used to determine whether the supply water temperature is appropriate for heating or cooling. The sensor should be located on the water supply in an area where there is continuous water flow. A 3-way EOC valve is recommended.

AAF-HermanNelson Model AV Unit Ventilators 45

Application Considerations

In addition:

1 Heating Operation: When the room temperature is

2°F or more below the heating setpoint and hot water is available, the EOC valve should open and remain open until the room temperature becomes equal to the heating setpoint or higher.

2 Cooling Operation: When room temperature is 2°F

or more above the cooling setpoint and cold water is available, the EOC valve should open and remain open until the room temperature becomes equal to the cooling setpoint or less.

3 Operation Due to Outside Air Temperature: If the

outside air temperature is equal to or less than 35°F, then the EOC valve should open and remain open until the outdoor air temperature reaches 37°F. or higher.

Heating EOC Valve

2 Operation Due To Outside Air Temperature: If the

outside air temperature is equal to or less than 35°F, and the face and bypass damper is in the full bypass position, the EOC valve should open. The valve should remain open until the outdoor air temperature reaches 37°F or higher or if the face and bypass damper is not in the full bypass position.

Water Coil Low Air Temperature Limit (Freezestat) Operation

The Water Coil Low Air Temperature Limit, or freezestat, function is intended to help protect the water coil from extremely low air conditions. All units with hydronic coils ship with a freezestat. The freezestat has a cut-out temperature setting of no less than 38±3°F and a cut-in temperature setting of approximately 48±3°F. The freezestat is intended as a backup in case the normal operating controls fail to protect the equipment. It is used in the following manner:

For steam or hot water heat only with face and bypass damper control; chilled water cooling with steam or hot

Face And Bypass Damper Control Applications

water heating (4 pipe) with face and bypass damper control; steam or hot water heat with face and bypass damper control coupled DX cooling:

Hot Water Heat Only or Chilled Water Cooling And Hot Water Heating (2 Pipe) :

The length of the freezestat is

secured to the leaving air face of the heating coil. When

The heating EOC valve should be a normally open, spring return (open), two position valve. In addition:

1 Heating Operation: When the room temperature is

2°F or more below the heating setpoint, the EOC valve should open and remain open until the room temperature becomes equal to the heating setpoint or higher.

2 Operation Due To Outside Air Temperature: If the

outside air temperature is equal to or less than 35°F, the EOC valve should open, the EOC should then remain open until the outdoor air temperature reaches 37°F. or higher.

Cooling EOC Valve

For chilled water cooling with steam or hot water heating (4 pipe) with face and bypass damper control; chilled water cooling only with face and bypass damper control; chilled water cooling with face and bypass damper control coupled electric heat:

The cooling EOC valve should be a normally closed, spring return (closed), two position valve.

1 Cooling Operation: When room temperature is 2°F

or more above the cooling setpoint, the EOC valve should open and remain open until the room temperature becomes equal to the cooling setpoint or less.

the freezestat cuts out due to low temperatures the following should occur:

• The outdoor air damper is closed.

• The heating EOC valve is forced to full open.

• The face and bypass damper modulates as needed to

maintain space temperature.

When the freezestat cuts in after cut-out, normal operation may return.

Chilled Water Cooling With Hot Water Heating (4 Pipe):

If the cooling coil is in the first position and the heating coil in the second position, the freezestat is secured to the leaving air face of the first position coil (cooling coil).

Note: The freezestat is placed between the first and second

coils. If you use glycol in the first coil, then you may move the freezestat to the leaving air side of the second coil. If you do not use glycol in the first coil, leave the freezestat where it is.

If the cooling coil is in the second position, the heating coil is in the first position and the heating coil is hot water, the freezestat is secured to the leaving air face of the first position coil (heating coil).

When the freezestat cuts out due to low temperatures, the following should occur:

• The outdoor air damper is closed.

• The heating EOC valve is forced to full open.

• The face and bypass damper modulates as needed to maintain room temperature.

46 McQuay Catalog 1600

Application Considerations

When the freezestat cuts in after cut-out, normal operation may return.

Chilled Water Cooling Only: The freezestat is secured to

the leaving air face of the cooling coil. When the freezestat cuts out due to low temperatures, the following should occur:

• The outdoor air damper is closed.

• The cooling EOC valve is forced to full open.

• If cooling is required, the face and bypass damper

modulates as needed to maintain space temperature.

When the freezestat cuts in after cut-out, normal operation may return.

Chilled Water Cooling With Electric Heat: The freezestat

is secured to the leaving air face of the cooling coil. When the freezestat cuts out due to low temperatures the following should occur:

• The outdoor air damper is closed.

• The cooling EOC valve is forced to full open.

• If cooling is required, the face and bypass damper

modulates as needed to maintain room temperature.

• If heating is required, the face and bypass damper goes to full face and electric heat is used as needed to maintain space temperature.

When the freezestat cuts in after cut-out, normal operation may return.

DX Cooling With Hot Water Heat & face and bypass Control:

The freezestat is secured to the leaving air face of the hot water heating coil. When the freezestat cuts out due to low temperatures, the following should occur:

• The compressor (condensing unit) is de-energized.

• The outdoor air damper is closed.

• The heating EOC valve is forced to full open.

• The face and bypass damper modulates as needed to

maintain space temperature.

When the freezestat cuts in after cut-out, normal operation may return.

Valve Control Applications

System freeze protection must be considered on valve controlled units utilizing hydronic coils. Non-flowing water in heating or cooling coils that are exposed to freezing outdoor air can freeze and rupture the coil (after the modulating valve shuts). The modulating control valve must be correctly sized and the supply water temperature controlled to ensure constant water flow. If this cannot be guaranteed, use an antifreeze solution to eliminate the possibility of coil freeze.

Hot Water Heat Only or Chilled Water Cooling And Hot Water Heating (2 Pipe):

The freezestat is secured to the leaving air face of the hot water heating coil. When the freezestat cuts out due to low temperatures, the following should occur:

• The outside air damper is closed.

• The unit fan is de-energized.

• The heating valve is forced to full open.

When the freezestat cuts in after cut-out, normal operation may return.

Chilled Water Cooling With Hot Water Heating (4 Pipe):

If the cooling coil is in first position and the heating coil is in second position, the freezestat is secured to the leaving air face of the first position coil (cooling coil).

Note: The freezestat is placed between the first and second

coils. If you use glycol in the first coil, then you may move the freeze stat to the leaving air side of the second coil. If you do not use glycol in the first coil, leave the freezestat where it is.

If the cooling coil is in the second position, the heating coil is in the first position, and the heating coil is hot water, the freezestat is secured to the leaving air face of the first position coil (heating coil).

When the freezestat cuts out due to low temperatures, the following should occur:

• The outdoor air damper is closed.

• The unit fan is de-energized.

• The heating valve is forced to full open.

When the freezestat cuts in after cut-out, normal operation may return.

Chilled Water Cooling Only: The freezestat is secured to

the leaving air face of the cooling coil. When the freezestat cuts out due to low temperatures, the following should occur:

• The outdoor air damper is closed.

• The cooling valve is forced to full open.

When the freezestat cuts in after cut-out, normal operation may return.

Chilled Water Cooling Coupled With Electric Heat: The

freezestat is secured to the leaving air face of the cooling coil. When the freezestat cuts out due to low temperatures, the following should occur:

• The outdoor air damper is closed.

• The cooling valve is forced to full open.

• Electric heat is used as needed to maintain space

temperature.

When the freezestat cuts in after cut-out, normal operation may return.

AAF-HermanNelson Model AV Unit Ventilators 47

Application Considerations

DX Cooling With Hot Water Heat & Valve Control: The

freezestat is secured to the leaving air face of the hot water heating coil. When the freezestat cuts out due to low temperatures, the following should occur:

• The compressor (condensing unit) is de-energized.

• The outdoor air damper is closed.

• The unit fan is de-energized.

• The heating valve is forced to full open.

When the freezestat cuts in after cut-out, normal operation may return.

Unit Installation

The floor unit ventilator is typically applied exposed on an outside wall below a window in the classroom. This allows fresh air (outdoor air) to be directly fed into the classroom after filtering or tempering. The floor unit is usually mounted flush against the wall with the fresh air opening in the back and the return air opening in the front (

Figure 53). All units have a fully insulated back with

gasketing for added protection.

Wall and Floor Considerations

It is critical to consider the floor and wall structures when installing floor-mounted unit ventilators. The following requirements apply:

• The unit must be securely mounted against an outside wall into which an opening is cut for an outdoor air intake louver.

• Placement of the outdoor air intake louver is critical for proper ventilation. It must be unobstructed, with no plants, trees or walls blocking the opening within 3 feet.

• Four pre-drilled holes are provided for securing the unit to the wall. Structural members must be available in the wall to support these attachments. Securing the unit to the wall compresses the unit back insulation and gasketing to help prevent air leaks and freezing of piping or coils.

• The floor must have sufficient strength to support the unit and prevent tipping.

• Space must be available under the floor to feed piping supply and return lines to the unit.

The following are general instructions for suggested applications. In all cases, good engineering practices and local codes must be followed.

Figure 53. Recessed Wall Louver Installation Detail

Internal Column For Wall Bracing (By Others)

Lintel

Weep Holes

Caulk Top And Two

Sides Of Louver

Lag Screws (By Others)

Pipe Tunnel

Unit Gasket

Sealed Mortar Bed

Caulk

Bird Screen

Floor

Unit Insulating Blanket

Back Of Unit

Unit Outside Air Opening

Unit Bottom Gasket

Seal Under Unit

48 McQuay Catalog 1600

Application Considerations

Wall Louvers

The outdoor air wall louver is usually set directly back of the unit ventilator. The position of the wall louver is determined in general by the building construction. The top of the lower channel of the louver frame should be at least 1/2" below the level of the inlet to the unit ventilator. However, if a high intake opening is necessary, the top of this opening should be not more than 28" above the surface upon which the unit ventilator will set.

Recessed Wall Louvers

Set recessed wall louvers into the wall in a bed of mortar with the face of the louver frame set slightly inside the wall line. The complete wall louver frame must be level with the face plumb and the louver frame set so that the drain holes on the bottom are toward the outside of the building.

The mortar should seal the frame perimeter water-tight to help prevent leaks. Do not block drain holes in the frame with mortar (

Figure 54. Recessed Wall Louver Installation Detail

Louvers

Figure 54).

Lintel (By Others)

Bird Screen

Flanged Wall Louvers

Set flanged wall louvers into the wall in a bed of mortar with the face of the louver frame flush with the wall line (

Figure 55

). The complete wall louver and frame must be

set level. Do not block drain holes in the frame with mortar.

Figure 55. Flanged Wall Louver Installation Detail

Caulk 4 Sides

Louvers

Drain Holes

(Do Not Block)

Flange

(4 Sides)

Lintel (By Others)

Bird Screen

Cement Mortar Pitched Away From Unit Toward Louver

1” Minimum

Use appropriate fasteners to secure the louver through the flange into the adjacent wall. Caulk the entire perimeter of the flange. For panel wall construction applications, caulk and seal the top and vertical sides of the vertical blade louver. Be sure that the drainage holes are pointing outward and that a metal channel is used to drain moisture (

Figure 56).

Drain Holes

(Do Not Block

WIth Mortar

or Caulk)

Cement Mortar Pitched Away From Unit Toward Louver

1" Minimum

Figure 56. Panel Wall Louver Installation Detail

Caulking

Weep Holes

Metal Channel

(Not Furnished)

Lintels

When brickwork is built up to the top of the intake, lintels must be used above the wall louvers. While the wall is still wet, finish the brick on the top, bottom and both sides of the intake opening with 1/2" cement mortar. With the standard location of the wall louver, the bottom of the intake opening must slope from the louver frame up toward the intake opening to a point 1" above the finished base of the unit. This provides a surface against

AAF-HermanNelson Model AV Unit Ventilators 49

Application Considerations

which the gasket at the bottom of the unit ventilator can be placed to help prevent any leakage of outdoor air under the unit.

If a metal sleeve connection is to be used between the unit ventilator and the wall louver, this sleeve must be installed after the unit ventilator is set, making a weathertight connection to the unit ventilator cabinet. Turn the sleeve over the edge of the louver frame by proper peening before the louver is finally installed.

Interior Considerations

The interior wall surface behind the unit ventilator must be smooth and level. A wall that is slightly out of plumb can cause major problems with outside air leakage into the room and unit. This could cause drafts and potentially freeze coils.

Be certain that no gap is left between the unit and the outside air louver opening. Otherwise, outside air can leak into the room.

A rubberized, self-adhering membrane around the outside air opening can be used to seal any air or water leaks that might result from construction. Provide a seal under the unit to prevent air infiltration. In addition, seal the unit top and side perimeters to prevent unnecessary air infiltration due to uneven walls.

Indoor Air Exhaust Considerations

All outdoor air introduced by the unit ventilator must leave the room in some way. In some states, exhaust vents are required by law. In states where vents are not required by law, a decision must be made about how best to handle this problem.

The venting system chosen should have the ability to exhaust varying amounts of air equal to the amount of outside air introduced by the floor unit ventilator. A constant volume system, such as a powered exhaust, is unable to respond to changing conditions. It will either exhaust too much air, resulting in a negative pressure, which draws in more outdoor air than desired. Or, it will exhaust too little air, resulting in increased positive pressure, which restricts the amount of outside air being brought into the room.

The AAF-HermanNelson Ventimatic shutter is a more economical solution to the problem. See Shutter Room Exhaust Ventilation” on page 26 for information on this system and its proper installation.

“Ventimatic™

50 McQuay Catalog 1600

Application Considerations

Unit Arrangements: 16-5/8" Deep

Arrangement AL

Arrangement AL units are 16-5/8” deep. They are available with both open (

Figure 57) and closed

(Figure 58) pipe tunnels. Choose closed pipe tunnel

Figure 57. Arrangement AL With Open Pipe Tunnel Figure 58. Arrangement AL With Closed Pipe Tunnel

Open Pipe Tunnel

arrangements when the pipe tunnel area will be open to air flow along the back of the unit.

Closed Pipe Tunnel

Installation With Floor-Level Outdoor Air Intake:

Piping

Lintel

(By Others)

Intake

Louver

Cement Mortar

(Pitch Away

From Unit)

Installation With Above-Floor-Level Outdoor Air Intake:

Important: Gasket Sealing Surface Required

Extra wall space is used to deliver fresh air to the unit outdoor opening.

Lintel

(By Others)

Intake Louver

Not Less Than 3"

Not More Than 21"

Cement Mortar

(Pitch Away

From Unit)

Piping

Important: Gasket Sealing Surface Required

Floor Line

Installation With Floor-Level Air Intake:

Extra wall space is used to deliver fresh air to the unit outdoor opening. Pipes and fin tube radiation can be run through the unit pipe tunnel. The back of the accessory must be field-installed.

Installation With Window Below Unit Top:

This installation allows window sills below the

Lintel (By Others)

Insulated Closure

Plate Accessory

Intake Louver

Not Less Than 3"

Not More Than 21"

Provide Drainage

Cement Mortar

(Pitch Away

From Unit)

Painted, Insulated Plate Accessory

Sash

standard 30" unit height to project a finished image from out-

Lintel

(By Others)

side. It also allows fresh air to be placed directly opposite the

Intake

Louver

unit outside air opening. A 9" painted, insulated plate accessory encloses the pipe tunnel on the back of the

Cement

Mortar

(Pitch Away

From Unit)

unit.

Piping

Floor Line

Important: Gasket Sealing Surface Required

Piping

Floor Line

AAF-HermanNelson Model AV Unit Ventilators 51

Application Considerations

Unit Arrangements: 21-7/8" Deep

Arrangement AL With Accessories

AL arrangements can be configured to a 21-7/8” depth utilizing field-installed ductwork (by others) to allow for

Arrangement AK

The AK arrangement has a partial adapter back with an open pipe tunnel and a rear outdoor inlet.

wall or piping considerations.

Figure 59. Arrangement AL With Accessories Figure 60. Arrangement AK

Installation With Insulated Accessory Top:

Allows for wall or piping considerations using field-installed duct (by others) to unit outdoor air

Installation With 2” Finished Stepdown Accessory Top:

This installation allows window sills below the standard 30" unit height to project a finished image from outside, while allowing for piping considerations using insulated duct (by others) to unit outdoor air inlet.

Insulated

Accessory

Piping

Lintel (By

Others)

Intake Louver

Cement

Mortar

(Pitch Away

From Unit)

Sash

Lintel

(By Others)

Intake Louver

Not More Than 12"

Cement

Mortar (Pitch

Away From

Unit)

To p

2” Finished Step Down Top

21-7/8"

Important: Gasket Sealing Surface Required

Accessory

21-7/8”

Important: Gasket Sealing Surface

FieldFabricated, Insulated Duct To Unit Outside Air Inlet

Floor Line

Piping

Insulated Duct (By Others)

Floor Line

Installation With Floor-Level Outdoor Air Intake:

This installation provides extra space for piping. Fresh air is directly opposite the unit outside air opening. The

Intake Louver

unit back and outdoor enclosure are insu-

Cement Mortar

lated.

Installation With Window Below Unit Top:

Allows window sills below the standard 30" unit height to project a finished image from outside. Allows fresh air to enter 27" from the floor to compensate for conditions that can arise during renovation or new construction. Similar to AN.

Lintel

(By Others)

Not More

Than 12"

(Pitch Away

From Unit)

2" Finished Step-Down Top

Sash

Lintel (By

Others)

Intake Louver

Not More

Than 28"

Cement Mortar

(Pitch Away

From Unit)

Open Pipe Tunnel

Piping

Floor

Important: Gasket Sealing Surface

Line

Piping

Floor Line

52 McQuay Catalog 1600

Application Considerations

Arrangement AN

The AN arrangement has a full adapter back with a closed pipe tunnel and a rear outdoor air inlet.

Figure 61. Arrangement AN

Closed Pipe Tunnel

Installation With Floor-Level Outdoor Air Intake:

Fresh air is directly opposite the unit outside air opening. Piping can be run through the insulated, closed piping tunnel. Unit top, back and vertical adapter back partitions are insulated.

Lintel

(By Others)

Intake Louver

Cement Mortar

(Pitch Away

From Unit)

Important: Gasket Sealing Surface

Piping

Floor Line

Arrangement AP

The AP arrangement has a full adapter back with a closed pipe tunnel and an outdoor air duct collar inlet.

Figure 62. Arrangement AP

Closed Pipe Tunnel

Installation With Floor-Level Outdoor Air Intake:

Allows fresh air to enter from the top of the unit from window intake situations that can arise during renovation or new construction.

Intake

Louver

Window Sash

“Goose Neck” Insulated Duct (By Others)

Duct Collar (By AAF)

Piping

Floor Line

Installation With Above-Floor Outdoor Air Intake:

Allows fresh air to enter from just below the top of the unit to the bottom. Thus, architectural and snow consider-

Lintel (By Others)

Intake Louver

Cement Mortar (Pitch

Away From Unit)

Not More

Than 28"

ations can be accommodated.

Piping

Floor Line

AAF-HermanNelson Model AV Unit Ventilators 53

Application Considerations

Arrangement AB

The AB arrangement has a full metal back cover that allows cutting a direct fresh air connection to the outside air opening when desired. The unit top, back vertical adapter back partitions and center inside metal back are insulated.

Figure 63. Arrangement AB

Closed Pipe Tunnel

Installation With Floor-To-Top Outdoor Air Inlet:

Lintel (By Others)

Intake Louver

Cement Mortar (Pitch

Away From Unit)

Not More Than 28"

Piping

Floor Line

54 McQuay Catalog 1600

Coil Selection

Quick Selection Procedure

The following procedure will provide you with a rough determination of unit capacity for cooling and/or heating based on the number of coil rows. Use capacity tables for final selection. Consult your local AAF-HermanNelson

Table 6: Chilled Water Cooling Capacity BTUH

80/67°F Entering Air Temperature; 45°F Entering Water Temperature;

10°F Water Temperature Rise

Rows 750 cfm 1000 cfm 1250 cfm 1500 cfm

2 17,900 23,600 31,500 38,800

3 21,700 33,300 41,100 51,200

4 27,800 35,600 43,400 56,700

Table 7: Hot Water Heating Capacity BTUH

60°F Entering Air Temperature; 160°F Entering Water Temperature;

6 Gpm Water Flow

Rows 750 cfm 1000 cfm 1250 cfm 1500 cfm

1 37,000 49,500 57,000 66,000

2 48,300 62,000 74,100 97,200

3 56,800 72,000 84,500 97,500

4 62,500 81,000 95,000 110,000

Table 8: Steam Heating Capacity BTUH

0°F Entering Air Temperature; 2 PSI Steam at 218.5°F

750 cfm 1000 cfm 1250 cfm 1500 cfm

Std Cap Hi Cap Std Cap Hi Cap Std Cap Hi Cap Std Cap Hi Cap

50,300 66,500 75,200 89,900 89,000 112,500 111,500 128,500

representative for details on the computer selection programs McQuay International provides for this purpose.

Table 9: Electric Heating Capacity BTUH

750 cfm 1000 cfm 1250 cfm 1500 cfm

Std Cap Hi Cap Std Cap Hi Cap Std Cap Hi Cap Std Cap Hi Cap

20,500 41,000 27,300 54,600 34,100 68,300 41,000 81,900

AAF-HermanNelson Model AV Unit Ventilators 55

Coil Selection

Coil Selection Procedure

Step 1: Determine Design Conditions

Determine design indoor and outdoor air temperatures in accordance with established engineering practices, as outlined in the ASHRAE Guide or other authoritative source. Indoor temperatures of 80°F dry bulb, 67°F wet bulb for summer and 70°F dry bulb for winter usually are acceptable for design or peak load conditions, even though the expected operating conditions of the system may be somewhat different.

Step 2: Determine Heating and Cooling Loads

Calculate design winter heating losses and summer cooling loads in accordance with the procedures outlined by the ASHRAE Guide or other authoritative source. Perhaps the greatest consideration in calculating design loads is solar heat gain. August solar heat values might be used for summer cooling loads, but should not be used for ventilation air or “natural cooling” capacity calculations; since these cooling loads reach their maximum in the spring and autumn months. The natural cooling capacity is usually calculated for 55° or 60°F outdoor air temperature (see

Table 10: Outdoor Air Ventilation Cooling Capacities Based

On 75°F Room Temperature

Unit Series Nominal CFM

S07 750 16.3 MBH 12.2 MBH

S10 1000 21.7 MBH 16.3 MBH

S13 1250 27.1 MBH 20.3 MBH

S15 1500 32.6 MBH 24.4 MBH

Ta bl e 10).

Outdoor Air Temperature

55°F. 60°F

STEP 3: Determine Air Quantity Required

Air quantity for heating applications is determined from circulation of a definite number of room air volumes per hour.

Ta bl e 11 gives the recommended number of room

air changes per hour.

Table 11: Recommended Room Air Changes Per Hour

Type of Space

Classrooms, Offices 6 to 9

Laboratories, Shops 6 to 8

Cafeterias & Kitchens 4-1/2 to 7

For rooms facing east, south or west, the higher values shown in the table should be used so adequate ventilation cooling will be available to prevent overheating during mild sunny weather. The following

Recommended number of

room air changes per Hour

equation is helpful to determine the CFM air delivery for any given rate of circulation:

Equation 3: CFM For Given Rate Of Circulation

Room Volume (cu ft) Room Changes per Hour×

-------------------------------------------------------------------------------------------------------------------- CFM=

In mechanical cooling applications, the total air quantity may be determined or verified by use of the sensible cooling load equation:

Equation 4: CFM Based On Sensible Cooling Load

CFM

Q sensible (space)

--------------------------------------------=

1.086xTD

Q sensible is the maximum sensible room load and T.D. is the temperature difference between the room design dry bulb temperature and the final or leaving-air dry bulb temperature. For these calculations, a T.D. of 20°F is usually assumed to be desirable to avoid delivering air too cold for comfort. This figure may be varied one or two degrees for reasons of practicality.

Note: The sensible load used in the preceding equation is the

space load and excludes the ventilation load.

Most areas have ventilation codes which govern the amount of ventilation air required for school applications. For other than school applications or areas not having codes, the ASHRAE Guide may be used for authoritative recommendations and discussion of the relation between odor control and outdoor air quantities.

The minimum outdoor air quantity recommended by ASHRAE is 15 CFM per person. Lower percent minimum outdoor air settings are more economical. In the interest of economy, it may be desirable to use lower percent minimums if there are no ventilation codes.

Step 4: Select Unit Size

The unit should be selected to meet or exceed the CFM delivery requirement previously determined. All model types are available with nominal capacities of 750, 1000, 1250 and 1500 CFM.

Heating Capacity

Unit heating capacity should be selected to equal or slightly exceed the computed room heat loss. For units installed for 100% recirculation, it is good practice to increase the heating capacity by 15% to aid in quick room warm-up. This allowance is unnecessary for units delivering a minimum outdoor air of 20% or more, since the outdoor air damper remains closed until the room is

56 McQuay Catalog 1600

Coil Selection

up to temperature. The heat normally expended in heating the minimum-percent outdoor air up to room temperature is available for quick warm-up purposes.

The heating required to warm the outdoor ventilating air up to room temperature must also be calculated. The Total Capacity should be used in sizing, piping, boilers, etc.

Cooling Capacity

Unit cooling capacity should be selected to equal or slightly exceed the sum of computed room sensible and latent heat gains (Room Total Capacity). When operating on the mechanical cooling cycle, the control system introduces a constant amount of outdoor air for ventilation. The latent and sensible heat gain from this outdoor ventilation air must be added to the room total cooling load before choosing the proper capacity unit.

Step 5: Freeze Protection

Constant pump operation is required whenever the outdoor air temperature is below 35°F. This will assist

in providing protection against freeze up of the system water piping and coils. To reduce the possibility of water coil freeze up on valve-controlled units, the valve must be selected properly to provide adequate water flow. See “Modulating Valve Sizing & Piping” on page 68. One of the steps below should be followed.

Chilled Water

Carry out one of the following steps to help protect against freezing:

• Drain the chilled water system during cold weather.

• Open the chilled water coil valves and operate the

chilled water circulating pump any time the outside air temperature is below 35°F.

• Use antifreeze in the system.

water pressure drops through the coil and piping system must be considered, as follows:

1 Divide the heating and/or cooling loads determined in

Step 2 by the applicable capacity correction factor shown in Tables

12 and 13 below to arrive at the calculated unit capacity required to take care of the capacity reduction caused by the glycol solution.

Table 12: Capacity Correction Factors for Ethylene Glycol

Ethylene Glycol% Weight 20% 30% 40%

Chilled Water 0.92 0.84 0.75

Hot Water 0.94 0.90 0.84

Table 13: Capacity Correction Factors for Propylene Glycol

Propylene Glycol% Weight 20% 30% 40%

Chilled Water 0.86 0.73 0.62

Hot Water 0.98 0.96 0.92

2 Determine the GPM required by entering the

appropriate chilled water cooling capacity table or hot water capacity chart using the calculated unit capacity.

3 Determine the water pressure drop by multiplying the

water pressure drop for the GPM determined above by the applicable pressure drop correction factor shown in Tables

Table 14: Pressure Drop Correction Factors For Ethylene

Glycol

Ethylene Glycol% Weight 20% 30% 40%

Chilled Water 1.15 1.22 1.34

Hot Water 1.08 1.11 1.19

Table 15: Pressure Drop Correction Factors For Propylene

Glycol

Ethylene Glycol% Weight 20% 30% 40%

Chilled Water 1.35 1.27 1.24

Hot Water 1.07 1.11 1.15

14 and 15 below.

Hot Water

Carry out one of the following steps to help protect against freezing:

• Use antifreeze in the system.

• Open the hot water coil valve and close the outdoor air

damper whenever a freezing condition is sensed at the coil. Freezestat furnished by Automatic Temperature Control supplier.

Step 6: Units With Antifreeze

If ethylene glycol or propylene glycol is used, its effect upon heating and cooling capacities and its effect on

AAF-HermanNelson Model AV Unit Ventilators 57

Coil Selection

Chilled Water Selection Example

Step 1: Determine Design Conditions

Assume the following design indoor and outdoor air temperatures are given:

• Outdoor design temperature = 96°F DB / 74°F WB

• Room design temperature = 76°F DB / 65°F WB

Step 2: Determine Cooling Loads

Assume the following cooling loads are given:

• Minimum total capacity (TC) = 43.4 MBH

• Minimum sensible capacity (SC) = 28.3 MBH

• Minimum outdoor air = 20%

• Room volume = 9,000 cubic feet

• Desired number of air changes per hour = 8

• Supply water temperature = 45°F EWT

Step 3: Determine Air Quantity Required

Equation 3 on page 56 indicates that to obtain eight room volumes per hour, a unit capable of delivering 1200 CFM standard air must be used, as follows:

CFM

RoomVolumeFt

()x RoomAirChangesPerHour()

--------------------------------------------------------------------------------------------------------------------------------=

CFM

9000 x8

------------------- 1 2 0 0 == 60

up the corresponding EWB (

Tab le 16). Enthalpy (H) is

calculated as follows:

% RA

Enthalpy H() RoomEnthalpy

Enthalpy H() 30.06 0.8··()37.66 0.2()+ 31.58H==

--------------

× OutdoorEnthalpy

100

×+=

%OA

------------100

Referring to Ta bl e 16, EWB for 31.58H = 67°F

Look Up Capacities

Look up the Chilled Water Cooling Coil Capacity Table for our calculated values and cooling loads (ED-18507):

• Unit size: 1250 cfm

• Entering dry bulb (EDB) = 80

• Entering wet bulb (EWB) = 67°F

• Supply water temperature (EWT) = 45°F

Under these conditions, the 4-row coil produces:

• 43.4 MBH (TC)

• 28.3 MBH (SC)

• 8.8 GPM

• 6.8 ft. H20 (WPD)

• 10°F (TR)

Leaving air temperatures dry bulb °F (LDB) and wet bulb °F (LWB) may be calculated as follows:

This indicates that an S13 Unit Ventilator should be used which delivers 1250 CFM.

Step 4: Select Unit Size

Determine the water flow (GPM), water temperature rise and the coil pressure drop as follows:

Determine Entering Dry Bulb Temperature

The entering dry bulb (EDB) temperature is calculated using the following formula:

% RA

EDB RoomDBx

EDB 76 0.8··()96()0.2()+ 80°F==

-------------100

OutdoorDB

Determine Entering Wet Bulb Temperature

The entering wet bulb (EWB) temperature is determined by calculating the Enthalpy (H) at saturation, then looking

×+=

%OA

------------100

LDB EDB

LWBH EWBH

SC BTUH()

---------------------------------–80

CFM 1.085×

TC BTUH()

-----------------------------– 31.62

CFM 4.5×

28300

-------------------------------– 59.1°F=== 1250 1.085×

50900

-------------------------– 23.9=== 1250 4.5×

From Ta bl e 16 on page 59:

LWB at 23.9 H = 56.1°F.

Note: Interpolation within each table and between sets of

tables for each unit series is permissible.

For conditions of coil performance beyond the scope of the catalog selection procedures, AAF-HermanNelson offers computer selection programs for chilled water, hot water and steam coils. Consult your local AAFHermanNelson representative for details.

58 McQuay Catalog 1600

Coil Selection

Table 16: Enthalpy (H) at Saturation But Per Pound Of Dry Air

Wet Bu lb Tem p . °F.

50 20.30 20.36 20.41 20.47 20.52 20.58 20.64 20.69 20.75 20.80

51 20.86 20.92 20.97 21.03 21.09 21.15 21.20 21.26 21.32 21.38

52 21.44 21.50 21.56 21.62 21.67 21.73 21.79 21.85 21.91 21.97

53 22.02 22.08 22.14 22.20 22.26 22.32 22.38 22.44 22.50 22.56

54 22.62 22.68 22.74 22.80 22.86 22.92 22.98 23.04 23.10 23.16

55 23.22 23.28 23.34 23.41 23.47 23.53 23.59 23.65 23.72 23.78

56 23.84 23.90 23.97 24.03 24.10 24.16 24.22 24.29 24.35 24.42

57 24.48 24.54 24.61 24.67 24.74 24.80 24.86 24.93 24.99 25.06

58 25.12 25.19 25.25 25.32 25.38 25.45 25.52 25.58 26.65 25.71

59 25.78 25.85 25.92 25.98 26.05 26.12 26.19 26.26 26.32 26.39

60 26.46 26.53 26.60 26.67 26.74 26.81 26.87 26.94 27.01 27.08

61 27.15 27.22 27.29 27.36 27.43 27.50 27.57 27.64 27.71 27.78

62 27.85 27.92 27.99 28.07 28.14 28.21 28.28 28.35 28.43 28.50

63 28.57 28.64 28.72 28.79 28.87 28.94 29.01 29.09 29.16 29.24

64 29.31 29.39 29.46 29.54 29.61 29.69 29.76 29.84 29.91 29.99

65 30.06 30.14 30.21 30.29 30.37 30.45 30.52 30.60 30.68 30.78

66 30.83 30.91 30.99 31.07 31.15 31.23 31.30 31.38 31.46 31.54

67 31.62 31.70 31.78 31.86 31.94 32.02 32.10 32.18 32.26 32.34

68 32.42 32.50 32.59 32.67 32.75 32.84 32.92 33.00 33.08 33.17

69 33.25 33.33 33.42 33.50 33.59 33.67 33.75 33.84 33.92 34.01

70 34.09 34.18 34.26 34.35 34.43 34.52 34.61 34.69 34.78 34.86

71 34.95 35.04 35.13 35.21 35.30 35.39 35.48 35.57 35.65 35.74

72 35.83 35.92 36.01 36.10 36.19 36.29 36.38 36.47 36.56 36.65

73 36.74 36.83 36.92 37.02 37.11 37.20 37.29 37.38 37.48 37.57

74 37.66 37.76 37.85 37.95 38.04 38.14 38.23 38.33 38.42 38.52

75 38.61 38.71 38.80 38.90 38.99 39.09 39.19 39.28 39.38 39.47

76 39.57 39.67 39.77 39.87 39.97 40.07 40.17 40.27 40.37 40.47

77 40.57 40.67 40.77 40.87 40.97 41.08 41.18 41.28 41.38 41.48

78 41.58 41.68 41.79 41.89 42.00 42.10 42.20 42.31 42.41 42.52

79 42.62 42.73 42.83 42.94 43.05 43.16 43.26 43.37 43.48 43.58

80 43.69 43.80 43.91 44.02 44.13 44.24 44.34 44.45 44.56 44.67

81 44.78 44.89 45.00 45.12 45.23 45.34 45.45 45.56 45.68 45.79

82 45.90 46.01 46.13 46.24 46.36 46.47 46.58 46.70 46.81 46.93

83 47.04 47.16 47.28 47.39 47.51 47.63 47.75 47.87 47.98 48.10

84 48.22 48.34 48.46 48.58 48.70 48.83 48.95 49.07 49.19 49.31

85 49.43 49.55 49.68 49.80 49.92 50.05 50.17 50.29 50.41 50.54

.0 .1 .2 .3 .4 .5 .6 .7 .8 .9

Tenths Of A Degree

AAF-HermanNelson Model AV Unit Ventilators 59

Coil Selection

Hot Water Heating Selection

For proper temperature control, do not oversize the heating coil. Select the hot water coil that just slightly exceeds the required heating capacity. Hot water coils are offered in three capacities. The low-capacity (65) coil and the high-capacity (66) coil can be used as heating only or in conjunction with a chilled-water or directexpansion cooling coil. The 3-row hot water coil (67) can be used as a super-high-capacity hot water coil in applications that require high heating capacities, such as in extremely cold climates or when a high percentage of outdoor air is utilized.

A 4-row heating coil cannot be used in conjunction with a separate cooling (4-row) coil since there is only sufficient space in the unit to accommodate a total of 6 rows of coil. See

“Available Coil Combinations” on page

75 and “Heat/Cool Units” on page 77.

Quick Selection Method Using MBH/∆T

Once the unit size has been selected, the MBH/∆T factor can be utilized to quickly and accurately determine coil size and minimum GPM, where:

∆T = Entering Water Temp - Entering Air Temp

For example, assume an entering water temperature of 180°F, an entering air temperature of 55°F and a total heating load of 75 MBH. Then,

∆T = 180 - 55 = 125

and,

MBH/∆T = 75/125 = 0.6

Assume we want to size for the S13, 1250 cfm unit determined in the coil selection example previously given for cooling. Referring to Figures

1 Enter each chart at MBH/∆T = 0.6.

2 Move horizontally to the right to intersect the unit 1250

curve.

3 Project downward for GPM requirement.

It is quickly seen that the 1-row coil (Figure 64 on page

61) does not meet the heating load. The 2-row coil (Figure 65 on page 62) can meet the requirement with

3.4 GPM. The 4-row coil (Figure 67 on page 63) is somewhat oversized.

64 through 67:

Two-Pipe Chilled-Water/Hot-Water Applications

The foregoing selection procedures are for heating-only or for 4-pipe heating/cooling applications using separate heating and cooling coils.

In 2-pipe chilled-water/hot-water applications, the same coil is used for chilled water during the cooling season and for hot water during the heating season. In this case, the same GPM will be used for hot water as was required for chilled water. It is necessary to determine only the supply water temperature required to satisfy the heating requirements. To do so:

1 Enter the appropriate chart at the known GPM.

2 Project upward to the size unit that is to be used.

3 Project a line horizontally across to obtain MBH/∆T.

4 Divide the required MBH by the MBH/∆T factor

obtained from the chart.

This will give the required temperature difference between the supply water temperature and the entering air temperature. Supply water temperature can then be determined by adding the entering air temperature to this temperature difference.

Note: For 2-pipe chilled-water/hot-water coils, heating capacity

is approximately 4 to 5% higher than that for standardcapacity coils at the same GPM.

Table 17: Hot Water Coil Pressure Drop (Ft. H20)

Unit Coil Rows

Series S07

750 cfm Nominal

Series S10

1000 cfm

Nominal

Series S13

1250 cfm

Nominal

Series S15

1500 cfm

Nominal

1 row coil 0.6 2.5

2 row coil 1.2 4.9 11 19.6

3 row coil 2.6 5.9 10.5 16.4

4 row coil 6.6 11.7 18.3 26.4 35.9

1 row coil 0.6 2.5 5.63

2 row coil 3.5 7.8 13.9

3 row coil 2.9 6.5 11.6 18.1 26.0 35.4

4 row coil 4.3 7.6 11.9 17.2 23.4

1 row coil 0.6 2.6 5.8 10.3

2 row coil 2.3 5.2 9.2

3 row coil 2.8 5.0 7.8 11.2

4 row coil 3.2 5.7 8.9 12.8 17.4

1 row coil 6.34 6.34 6.34 11.3

2 row coil 2.7 6 10.7

3 row coil 3.3 5.9 9.2 13.2

4 row coil 2.4 4.3 6.7 9.6 13.1

2 4 6 8 10 12 14

Water Flow (GPM

60 McQuay Catalog 1600

Coil Selection

Two-Pipe Selection Example

In the example previously given for cooling, the required flow rate was 12.5 GPM for the 4 row coil in an S13 unit with 1250 cfm. If we assume a heating load of 74 MBH, we can determine the required temperature difference as follows:

1 Enter the 4-row table (Figure 67 on page 63) with 12.5

GPM.

2 Project up to the 1250 curve.

3 Project horizontally to the left to determine the MBH/

∆T factor of about 1.03.

4 Divide the required MBH (74) by the MBH/∆T factor

obtained (1.03) from the chart. The resulting temperature difference is 70.

Figure 64. 1-Row Hot Water Coil

0.8

0.7

1500SCFM

0.6

With a room design temperature of 70°F and assuming 20% outdoor air, the entering air temperature would be:

0 (.20) + 70 (.80) = 56°F

Therefore, the required supply water temperature would be: 70°F + 56°F = 126°F

Note: The 4 row coil has a very high heating capacity since it is

sized for air conditioning. For this reason, a low entering water temperature will usually satisfy the heating requirements. This temperature may be too low for other equipment (such as radiation or convectors) in the system. It is important that supply water temperature be kept as close to that required by the unit ventilator as possible. Higher than required water temperature can result in poor temperature control resulting in overheating.

1250SCFM

1000SCFM

0.5

MBH/dT

750SCFM

0.4

0.3

0.2 2345678910

GPM

AAF-HermanNelson Model AV Unit Ventilators 61

Coil Selection

Figure 65. 2-Row Hot Water Coil (Parallel Flow)

1.2

1.1

1500 SCFM

0.9

0.8

MBH/dT

0.7

0.6

0.5

0.4

0.3 2345678910

1250 SCFM

1000 SCFM

750 SCFM

GPM

Figure 66. 3-Row Hot Water Coil (Parallel Flow)

1.4

1.3

1.2

1.1

1500SCFM

0.9

MBH/dT

0.8

MBH/dT

0.8

0.7

0.6

0.5

0.4

0.3

0.3 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

1250SCFM

GPM

1000SCFM

750SCFM

62 McQuay Catalog 1600

Coil Selection

Figure 67. 4-Row, 2-Pipe Cold Water/Hot Water Coil (Counter Flow)

1.4

1.3

1.2

1.1

0.9

MBH/dT

0.8

0.7

0.6

0.5

0.4

0.3 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

1500SCFM

1250SCFM

1000SCFM

750SCFM

GPM

Steam Heating Selection

The maximum allowable steam pressure, especially in public buildings, is often fixed by state or local boiler codes. Steam Capacity in

Tab le 18 is based on steam supply pressure of 2 PSI gauge and steam temperature of 218.5°F.

To determine total capacity for conditions other than shown in the Steam Capacity

Table 18: Steam Heating Capacities - 2# Steam Coils

-20 -10 0 10 20 30 40 50 60 70

Unit

Airflow SCFM

MBH

Coil Capacity

Std 750 55.1 47.8 52.7 54.9 50.3 61.8 47.8 68.8 45.3 75.7 42.7 82.6 40.0 89.2 37.3 95.9 35.6 103.8 32.9 110.5

750

High 750 73.0 69.8 69.8 75.8 66.5 81.8 63.2 87.7 59.8 93.5 56.4 99.3 52.7 104.8 49.1 110.4 45.4 115.8 41.6 121.1

Std 1000 82.1 55.8 78.7 62.6 75.2 69.3 71.6 76.0 68.0 82.7 65.6 90.5 61.8 97.0 58.0 103.5 54.1 109.9 50.4 116.5

1000

High 1000 98.3 70.6 94.1 76.8 89.9 82.9 85.6 89.0 81.3 95.0 77.0 101.0 72.3 106.7 67.7 112.4 63.0 118.1 58.4 123.9

Std 1250 97.0 51.6 93.0 58.6 89.0 65.7 85.0 72.7 80.9 79.7 76.7 86.6 72.3 93.3 67.9 100.1 63.5 106.9 59.9 114.2

1250

High 1250 122.6 70.4 117.6 76.7 112.5 83.0 107.3 89.2 102.1 95.3 96.8 101.4 91.2 107.3 85.6 113.2 80.0 119.0 74.4 124.9

Std 1500 121.3 54.6 116.5 61.6 111.5 68.5 106.5 75.5 101.4 82.3 96.3 89.2 90.8 95.8 85.5 102.5 80.0 109.2 75.6 116.5

1500

High 1500 140.0 66.0 134.3 72.5 128.5 79.0 123.6 86.0 117.7 92.4 111.8 98.7 105.5 104.8 99.2 111.0 92.8 117.1 86.6 123.2

Data based on 2psig steam pressure @10°F superheat steam vapor.

Table 18, multiply the total

LAT, db

MBH

LAT, db

MBH

LAT, db

MBH

LAT, db

capacity given by the proper constant from the Steam Capacity Correction Factor in

Ta bl e 19.

Maximum steam pressure is 6 PSIG at coil inlet.

Traps are by others. Either float and thermostatic traps or thermostatic traps may be used.

Entering Air Temperature °F

MBH

LAT, db

MBH

LAT, db

MBH

LAT, db

MBH

LAT, db

MBH

LAT, db

MBH

LAT, db

AAF-HermanNelson Model AV Unit Ventilators 63

Coil Selection

Table 19: Steam Capacity Correction Factors

Steam Pressure

PSIG

0 0.97 0.97 0.97 0.96 0.97 0.97 0.97 0.96 0.96 0.96

2 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00

5 1.02 1.03 1.03 1.03 1.04 1.05 1.05 1.05 1.05 1.05

-20 -10 0 10 20 30 40 50 60 70

Entering Air Temperature Mixture, °F

Electric Heating Selection

Table 20: Electric Heat Capacities, Amps, Wire Sizing, and Over-Current Protection

230-60-1

265-60-1

208-60-3

230-60-3

460-60-3

Unit Type

CFM

Number of Electric Elements

MBH

Final Air Temp. °F (70°F Entering Air Temp.)

Air Temperature Rise

Electric Heating Amperes

Unit Minimum Circuit Ampacity

Maximum Fuse Size or Circuit Breaker Amps

Electric Heating Amperes

Unit Minimum Circuit Ampacity

Maximum Fuse Size or Circuit Breaker Amps

Electric Heating Amperes

Unit Minimum Circuit Ampacity

Maximum Fuse Size or Circuit Breaker Amps

Electric Heating Amperes

Unit Minimum Circuit Ampacity

Maximum Fuse Size or Circuit Breaker Amps

Electric Heating Amperes

Unit Minimum Circuit Ampacity

Maximum Fuse Size or Circuit Breaker Amps

AVS AVV AVR

36363636

6 12 8 1610201224

20.5 41 27.3 54.6 34.1 68.3 41 81.9

95.2 120.3 95.2 120.3 95.2 120.3 95.2 120.3

25.2 50.3 25.2 50.3 25.2 50.3 25.2 50.3

25 50 33.3 66.6 41.7 83.4 50 100

34.1 65.3 44.4 86.1 54.9 107.1 65.3 127.8

35 70 45 90 60 110 70 150

21.7 43.6 28.9 57.8 36.2 72.3 43.6 87.1

29.7 57 38.7 74.8 47.8 93 57 111.4

30 60 40 80 50 100 60 125

16.7 33.3 22.2 44.4 27.8 55.5 33.3 66.6

24 44.7 30.9 58.6 37.9 72.5 44.7 86.4

25 45 35 60 40 80 45 90

14.5 28.9 19.2 38.4 24.1 48.1 28.9 57.7

20.9 38.9 26.8 50.8 32.9 62.9 38.9 74.9

25 40 30 60 35 70 40 80

7.2 14.5 9.6 19.2 16.4 31.4 14.4 28.9

10.4 19.5 13.4 25.5 21.9 40.7 19.4 37.5

15 20 15 30 25 45 20 40

AVV

AVR

750 (S07) 1000 (S10) 1250 (S13) 1500 ((S15)

AVS AVV AVR

AVV AVR

AVS AVV AVR

AVV AVR

AVS AVV

AVR

AVV AVR

64 McQuay Catalog 1600

Coil Selection

Direct Expansion Cooling Coil Selection

Proper sizing of the field-supplied condensing units is important for trouble-free operation. An oversized condensing unit can reduce performance and cause operational problems such as:

• Compressor short cycling due to rapid pull down.

• Poor temperature and humidity control.

• Low saturated evaporator coil conditions.

• Low discharge air temperatures.

To properly size the unit ventilator, determine the cooling load based on May and September conditions at 1 pm when the classroom is occupied. Do not select units for

minimize the potential problems seen with oversized units.

Figure 68 shows the total capacity of the unit ventilator versus saturated evaporator temperature. The condensing unit manufacturer’s capacity versus saturated suction temperature can be cross-plotted on this chart with an allowance for suction line loss. The total capacity and saturated suction temperature for the total system can be determined from this cross plot. The sensible capacity can be determined by multiplying the total capacity by the sensible heat factor shown in

Ta bl e 21. July and August after 3 pm when the classroom is unoccupied. If the calculated cooling load falls between two unit sizes, select the smaller of the two units to

Figure 68. 2" DX Coil Estimated Performance (Mbh) At 115°F Liquid Temperature

Table 21: Sensible Factor At 45°F Saturation Temperature

750 1000 1250 1500

0.74 0.75 0.74 0.76

DX Coil Performance @ 115°F Liquid Inlet

Entering Air Temperature 80°Fdb/67°Fwb

UV750

UV1000

UV1250

UV1500

Total Capacity MBH

35 40 45 50 55

Evaporator Saturation Temperature °F

AAF-HermanNelson Model AV Unit Ventilators 65

Valve Selection

Face and Bypass End-Of-Cycle Valve Sizing & Piping

MicroTech II face and bypass damper control requires a DDC end-of-cycle (EOC) valve for each hydronic coil. End-of-cycle (or two position) valves are either full-open or full-closed. To select an end-of-cycle valve:

1 Determine the flow of water and the corresponding

pressure drop through the coil.

2 Obtain the pressure difference between the supply

and return mains.

3 Select a valve (Cv) on the basis of taking 10% of the

available pressure difference (at design flow) between the supply and return mains at the valve location. The valve should have a pressure drop less than or equal to that of the coil.

Ta bl e 22 gives the pressure drops at various water flow rates for the Cv of the valve listed. EOC valves for water applications can be either two-way or three-way. Units that have separate hot water and cooling coils (4-pipe) require a 3-way EOC valve to shut off the hot water flow at the end of the heating cycle.

Hot water, heating only units and chilled/hot water (2pipe) units also require a 2-way or 3-way EOC valve to shut off the hot water flow at the end of the heating cycle. The EOC valve is not required when a hot water reset schedule is used on 2-pipe only units (no second coil).

Refer to the EOC valve label to determine the direction of flow. The EOC valve must be installed on the unit for which it was selected.

Table 22: Hot and Chilled Water End-Of-Cycle Valve Selection By Pressure Drop

2-Way Hot Water EOC Valve (7.0 Cv), FNPT, Normally Open

Water Flow GPM (L/s):

WPD1 Ft of H2O (kPa):

Water Flow GPM (L/s):

WPD Ft of H2O (kPa):

Water Flow GPM (L/s):

WPD Ft of H2O (kPa):

Water Flow GPM (L/s):

WPD Ft of H2O (kPa):

WPD = Water Pressure Drop

7 (0.44) 9.9 (0.62) 12.1 (0.76) 14 (0.88) 15.7 (0.99) 22.1 (1.39) 27.1 (1.71) 31.3 (1.98) 35.0 (2.20)

2.3 (6.9) 4.6 (13.8) 6.9 (20.7) 9.2 (27.6) 11.6 (34.5) 23.1 (69.0) 34.7 (103.4) 46.2 (138.0) 57.8 (172.4)

3-Way Hot Water EOC Valve (5.0 Cv), FNPT, Normally Open

5 (0.32) 7.1 (0.45) 8.7 (0.55) 10 (0.63) 11.2 (0.71) 15.8 (1.00) 19.4 (1.22) 22.3 (1.41) 25.0 (1.58)

2.3 (6.9) 4.6 (13.8) 6.9 (20.7) 9.2 (27.6) 11.6 (34.5) 23.1 (69.0) 34.7 (103.4) 46.2 (138.0) 57.8(172.4)

2-Way Chilled Water EOC Valve (7.0 Cv), FNPT, Normally Open

7 (0.44) 9.9 (0.62) 12.1 (0.76) 14 (0.88) 15.7 (0.99) 22.1 (1.39) 27.1 (1.71) 31.3 (1.98) 35.0 (2.20)

2.3 (6.9) 4.6 (13.8) 6.9 (20.7) 9.2 (27.6) 11.6 (34.5) 23.1 (69.0) 34.7 (103.4) 46.2 (138.0) 57.8 (172.4)

3-Way Chilled Water EOC Valve (5.0 Cv), FNPT, Normally Open

5 (0.32) 7.1 (0.45) 8.7 (0.55) 10 (0.63) 11.2 (0.71) 15.8 (1.00) 19.4 (1.22) 22.3 (1.41) 25.0 (1.58)

2.3 (6.9) 4.6 (13.8) 6.9 (20.7) 9.2 (27.6) 11.6 (34.5) 23.1 (69.0) 34.7 (103.4) 46.2 (138.0) 57.8 (172.4)

66 McQuay Catalog 1600

Valve Selection

Hot Water EOC Valve Piping

Hot water (or chilled water/hot water 2-pipe) EOC valves are furnished normally open to the coil. When the valve is de-energized (off) there is full flow through the coil. Energizing the valve shuts off the water flow.

Figure 69. 2-Way Hot Water EOC Valve Piping

Return

Balancing & Shutoff Valve

2-way EOC Valve

Shutoff Valve

Supply

Unions

S5 Sensor (2-pipe CW/HW Units Only)

Figure 70. 3-Way Hot Water EOC Valve Piping

Return

Balancing & Shutoff Valve

(Bypass)

S5 Sensor 2-pipe CW/HW Units Only)

Supply

Balancing Valve

3-way EOC Valve

Unit Coil

Return

Supply

Shutoff Valve

Union

Unit Coil

Return

Supply

Union

Chilled Water EOC Valve Piping

Chilled water EOC valves are furnished normally closed

to the coil. When the valve is de-energized (off) there is

no flow through the coil. Energizing the valve allows flow

through the coil.

Figure 71. 2-Way Chilled Water EOC Valve Piping

Return

Balancing & Shutoff Valve

2-way EOC Valve

Unions

Shutoff Valve

Supply

Figure 72. 3-Way Chilled Water EOC Valve Piping

Return

Balancing & Shutoff Valve

Bypass

Supply

Balancing Valve

3-way EOC Valve

Shutoff Valve

Unit Coil

Return

Supply

Union

Unit Coil

Return

Supply

Union

AAF-HermanNelson Model AV Unit Ventilators 67

Valve Selection

Modulating Valve Sizing & Piping

The unit ventilator control valve is expected to vary the quantity of water that flows through the coil in a modulating fashion. Any movement of the valve stem should produce some change in the amount of water that flows through the coil. Oversized control valves cannot do this.

For example, assume that, when the control valve is fully open, the pressure drop through the coil is twice as great as the drop through the valve. In this case, the control valve must travel to approximately 50% closed before it can begin to have any influence on the water flow through the coil. The control system, no matter how sophisticated, cannot overcome this. Oversized control valves can also result in hunting which will shorten the life of the valve and actuator

2 Obtain the pressure difference between the supply

and return mains.

3 Select a valve (Cv) from Ta bl e 23 on the basis of

taking 50% of the available pressure difference (at design flow) between the supply and return mains at the valve location. The valve should have a pressure drop greater than that of the coil. Whenever possible there should be at least 11 feet of water (5psi) (32.9 kPa) pressure drop across the valve.

Modulating valves for water applications can be either 2-way or 3-way. Refer to the modulating valve label to determine the direction of flow. The modulating valve must be installed on the unit for which it was selected.

and possibly damage the coil.

The modulating valve furnished for steam applications is

To correctly select the modulating valve:

1 Determine the flow of water and the corresponding

pressure drop through the coil.

Table 23: Hot and Chilled Water Modulating Valve Selection By Flow Rate

Valve Pressure Drop [ft of H2O (kPa)] at Listed Water Flow Rate [GPM (L/s)]

Connect

ion

Hot Water 2-Way Modulating Valve, Normally Open

1.3

1/2 inch

2.2

1/2 inch

4.4

1/2 inch

6.6

3/4 inch

7.5

3/4 inch

Hot Water 3-Way Modulating Valve, Normally Open

2.0

1/2 inch

4.0

1/2 inch

6.0

3/4 inch

Chilled Water 2-Way Modulating Valve, Normally Closed

2.0

1/2 inch

4.0

1/2 inch

Chilled Water 3-Way Modulating Valve, Normally Closed

2.0

1/2 inch

4.0

1/2 inch

6.0

3/4 inch

Rcmnd

Flow Rates2 (.13)3 (.19)4 (.25)5 (.32)6 (.38)7 (.44)8 (.51)

2 - 5 GPM

.13 -.32 L/s

5 - 8.5 GPM

.32 -.54L/s

8.5 -12.3 GPM

.54 -.78 L/s

2-5 GPM

.78 - 1.1 L/s

Over 16.8 GPM

Over 1.1 L/s

2 - 8 GPM

.13 -.51 L/s

8 - 14 GPM

.51 -.88 L/s

Over 14 GPM

Over.88 L/s

2 - 8 GPM

.13 -.51 L/s

8 - 14 GPM

.51 -.88 L/s

2 - 8 GPM

.13 -.51 L/s

8 - 14 GPM

.51 -.88 L/s

Over 14 GPM

Over.88 L/s

5.5

12.3

21.8

34.1

(16.6)

(36.6)

(65.5)

5.2

(15.9)

5.2

(15.9)

5.2

(15.9)

7.5

(22.8)

9.2

(27.6)

9.2

(27.6)

9.2

(27.6)

––

––– – – –

––– – – – – – – –

––– – – – – – – – – – – –

2.3

(6.9)

––– – – – –

––– – – – – – – – – –

2.3

(6.9)

––– – – – –

2.3

(6.9)

––– – – – –

––– – – – – – – – – –

––– – – – – ––––––––

(102)

11. 9

17.4

(51.0)

20.8

(62.1)

20.8

(62.1)

20.8

(62.1)

23.4

(69.7)

28.3

(84.8)

28.3

(84.8)

28.3

(84.8)

(35.9)

14.4

(43.5)

14.4

(43.5)

14.4

(43.5)

30.5

(91.0)

10.2

(30.3)

36.9

(110)

36.9

(110)

36.9

(110)

a 2-way, normally open to the coil configuration (see “Modulating Steam Valve Selection” on page 70 for application).

9 (.57)

(115.2)

(.63)

(.64)

38.6 – – – ––––––––

12.9

16.0

(47.6)

14.4

(43.5)

14.4

(43.5)

14.4

(43.5)

19.3

(57.9)

17.4

(52.4)

17.4

(52.4)

17.4

(52.4)

(38.6)

– – – –––––––––

11. 7

(35.2)

– – – –––––––––

11. 7

(35.2)

– – – –––––––––

11. 7

(35.2)

(.76)

23.0

(69.0)

11. 0

(69.0)

20.8

(62.1)

20.8

(62.1)

20.8

(62.1)

(.82)

(.88)

(.95)

(1.0)

(1.1)

27.0 –––––––

(80.7)

12.9

15.0

17.2

19.5

22.0

(80.7)

24.4

(73.1)

24.4

(73.1)

24.4

(73.1)

(44.8)

(51.0)

(58.6)

10.5

(31.5

28.3 ––––––

(84.8)

9.7

11. 2

(29.0)

28.3

(84.8)

28.3

(84.8)

9.7

(29.0)

12.8

(33.8)

(37.9)

––––––

11. 2

12.8

(33.8)

(37.9)

–––

(66.2)

11.9

13.3

(35.7)

(40.0)

14.4

16.2

(43.5)

(48.3)

14.4

16.2

(43.5)

(48.3)

(1.2)

14.8

(44.1)

18.0

(53.8)

18.0

(53.8)

(1.3)

16.4

(49.0)

20.0

(60.0)

20.0

(60.0)

68 McQuay Catalog 1600

Valve Selection

Hot Water Modulating Valve Piping

Modulating hot water (or chilled water/hot water 2-pipe) valves are furnished normally open to the coil. When the valve is de-energized (off) there is full flow through the coil. Energizing the valve allows a varying amount of water to bypass the coil.

Figure 73. 2-Way Hot Water Modulating Valve Piping

Return

Balancing & Shutoff Va;ve

2-way

Modulating Valve

Shutoff Valve

Supply

Unions

S5 Sensor (2-pipe CW/HW Units Only)

Figure 74. 3-Way Hot Water Modulating Valve Piping

Return

3-way

Modulating Valve

N.C.

Balancing Valve

Common

N.O.

Unit Coil

Return

Supply

Balancing &  Shutoff Valve

Union

Unit Coil

Return

Supply

Chilled Water Modulating Valve Piping

Modulating chilled water valves are furnished normally closed to the coil. When the valve is de-energized (off) there is no flow through the coil. Energizing the valve allows flow through the coil in a modulating fashion.

Figure 75. 2-Way Chilled Water Modulating Valve Piping

Return

Balancing & Shutoff Valve

2-way

Modulating Valve

Unions

Shutoff Valve

Supply

Figure 76. 3-Way Chilled Water Modulating Valve Piping

Return

Balancing & Shutoff Valve

3-way

Modulating Valve

Common

Balancing Valve

N.C.

N.O.

Unit Coil

Return

Supply

Union

Unit Coil

Return

Supply

Union

Shutoff Valve

S5 Sensor (2-pipe CW/HW Units Only)

Union

Shutoff Valve

Supply

AAF-HermanNelson Model AV Unit Ventilators 69

Valve Selection

Steam Valve Sizing & Piping

End-Of-Cycle Steam Valve Selection

End-of-cycle, steam valves are either full-open or fullclosed. To select an end-of-cycle steam valve:

1 Obtain the supply steam inlet pressure.

2 Determine the actual heat requirement of the space to

be heated.

3 Select a steam valve (Cv) based on taking 10% of the

inlet steam pressure. For example, for a system with an inlet pressure of 2 psig, the valve should be sized based on a 0.2 psig pressure drop. The valve must have a capacity greater than or equal to that of the space to be heated.

Ta bl e 24 gives the steam capacity based on 10% of 2 psig and 5 psig inlet pressures at a 7.0 Cv rating.

Table 24: EOC Steam Valve Selection

Valve Inlet Pressure Capacity MBh Capacity Watts

2 psig (13.8 kPa) 43.9 12854

5 psig (34.5 kPa) 74.8 21924

Table 25: Modulating 2-Way Steam Valve Capacity1, Normally Open

Port

Code

Based on 1150 Btu/lb of steam

Cv Connection

2 1.3 1/2" (13mm) FNPT 19 24 32 38 5669 7128 9305 1127 0

3 2.2 1/2" (13mm) FNPT 33 41 54 65 9594 12062 15746 19072

4 4.4 1/2" (13mm) FNPT 65 82 107 130 19189 24125 31492 38144

5 5.5 3/4" (19mm) FNPT 82 103 134 163 23986 30156 39366 47681

6 7.5 3/4" (19mm) FNPT 11 2 140 183 222 32708 41122 53680 65019

7 10 1" (25mm) FNPT 149 187 244 296 43611 54829 71574 86692

8 14 1" (25mm) FNPT 208 262 342 414 61055 76760 100203 121369

2 psig Inlet Pressure 5 psig Inlet Pressure 13.8 kPa Inlet Pressure 34.5 kPa Inlet Pressure

Valve Capacity (MBh) Valve Capacity (Watts)

Modulating Steam Valve Selection

The steam modulating control valve is expected to vary the quantity of steam through the coil. Any movement of the valve stem should produce some change in the steam flow rate. To select a modulating steam valve:

1 Obtain the supply steam inlet pressure.

2 Determine the actual heat requirement of the space to

be heated.

3 Select a valve (Cv) from Ta bl e 25, which gives the

capacity range based on a 60% pressure drop at the low end of the range and 100% pressure drop at the high end of the range.

For example: With 2 psig (13.8 kPa) inlet pressure, the valve with port code 4, in the full open position, would have a 1.2 psig (8.3 of 2 psig) at 65 MBh (19,189 watts) and a 2 psig pressure drop at 82 MBh (24,125 watts). The valve should have a capacity less than or equal to the space to be heated.

kPa) pressure drop (60%

70 McQuay Catalog 1600

Valve Selection

Steam Valve Piping

End-of-cycle (EOC) and modulating valves for steam applications are 2-way, normally open, angle pattern valves. When the coil is de-energized (off) the steam flows through the coil. Energizing the EOC valve shuts off the flow of steam to the coil. Energizing the modulating valve varies the flow of steam in a modulating fashion. Refer to the steam valve label to determine the direction of flow. The steam valve must be installed on the unit for which it was selected.

All valves are shipped loose to help prevent shipping damage and to provide the installing contractor with maximum flexibility in making the field piping connection. The valves are field piped by others. They are factory wired for field hook-up.

Notes:

1 Refer to the label furnished on 2-way valves to

determine direction of flow through the valve.

2 The control valve must be installed on the unit in

which it was shipped. Indiscriminate mixing of valves among units can result in valves not properly sized for the desired flow rate.

3 The control valve should be installed so that there is

2" (51mm) minimum clearance to remove the actuator from the valve body. Provide unions for the removal of the unit coil and/or control valve. This is a future service consideration.

Figure 77. 2-Way Steam Valve Piping

Supply

Shutoff Valve

Unit Coil

Supply

Steam Trap

Equalizing Line

Shutoff Valve

Return

AAF-HermanNelson Model AV Unit Ventilators 71

General Data

AV General Data

Table 26: AV General Data

Nominal Airflow CFM (L/s):

Number of Fans:

Fan Data:

Filter Data:

Shipping Weight:

Coil Water Vol um e Gallons (Liters):

Size:

Nomina

l Size:

Diameter - in (mm)

Width- in (mm)

(mm)

Area - Ft2 (m2):

Quantity:

16-5/8" Deep Units:

21-7/8" Deep Units:

1 Row Coil:

2 Row Coil:

3 Row Coil:

4 Row Coil:

S07 S10 S13 S15

750 (340) 1000 (472) 1250 (590) 7500 (708)

2344

8.12(206mm) 8.12(206mm) 8.12(206mm) 8.12(206mm)

8.25(210mm) 8.25(210mm) 8.25(210mm) 8.25(210mm)

10 x 36-1/2 x 1 10 x 48-1/2 x 1 10 x 60-1/2 x 1 10 x 36-1/2 x 1

254 x 927 x 25 254 x 1232 x 25 254 x 1537 x 25 254 x 927 x 25

2.54(.24) 3.37(.31) 4.2(.39) 5.08(.47)

1112

350(168) 425(193) 495(225) 570(259)

370 (163) 445 (202) 525 (238) 600 (272)

0.25 (0.95) 0.31 (1.17) 0.38 (1.44) 0.44 (1.67)

0.45 (1.70) 0.57 (2.16) 0.69 (2.61) 0.82 (3.10)

0.64 (2.42) 0.82 (3.10) 1.01 (3.82) 1.19 (4.50)

0.83 (3.14) 1.08 (4.09) 1.32 (5.00) 1.57 (5.94)

Table 27: Fan & Fan Motor Data

Unit Series

750 750 (354) 1/4 216 2.2 1.2 1.1 1.0

1000 1000 (472) 1/4 277 2.8 1.6 1.4 1.3

1250 1250 (590) 1/4 335 3.3 1.9 1.7 1.5

1500 1500 (708) 1/4 445 4.4 2.6 2.3 2.0

Nominal

CFM (L/s)

Motor Unit Current At Listed Voltage, 60 Hz, Single Phase

hp watts 120 208 230 265

72 McQuay Catalog 1600

General Data

Available Unit Ventilator Combinations

Table 28: Available Unit Ventilator Combinations

Face & Bypass

Control

Valve Control

Design Series

Air Capacity

Vol tag e

Cooling Options

Heating Options

Basic F & B

AVS AV S AVB AV V AV V AV R AV R

D = 4

750 cfm, Standard Static = S07

1000 cfm, Standard Static = S10

1250 cfm = S13 S13 S13 S13 S13 S13 S13 S13

1500 cfm = S15 S15 S15 S15 S15 S15 S15 S15

115 - 60 - 1 = A A A A A

208 - 60 - 1 = C C C C C

230 - 60 - 1 = G G GGGGGG

265 - 60 - 1 = JJJJJJJJ

208 - 60 - 3 = D D D D

230 - 60 - 3 = H H H H

460 - 60 - 3 = K K K K

2 Row CW/HW 2 Pipe = U U U

3 Row CW/HW 2 Pipe = D D D

4 Row CW/HW 2 Pipe = E E E

2 Row CW = VVVVVVVV

3 Row CW = SSSSSSSS

4 Row CW = WWWWWWWW

DX (Non - Face And Bypass Control) = G G G G G G

None = Z Z Z Z

None = 00 00 00

HW One Row = 65 65 65 65 65

HW Two Row = 66 66 66 66 66

HW Three Row = 67 67 67 67 67

Steam Low Capacity = 68 68 68 68 68

Steam High Capacity = 69 69 69 69 69

Opposite End Drain Steam Low Cap = 78 78 78 78 78

Opposite End Drain Steam High Cap = 79 79 79 79 79

Low Electric Heat (3 element) = 12 12 12 12

High Electric Heat (6 element) = 13 13 13

4444444

S07S07S07S07S07S07S07

S10S10S10S10S10S10S10

Hydronic Reheat

Electric Heat/Cool

Basic Valve Control

Hydronic Reheat

Electric Heat/Cool

Electric Reheat

AAF-HermanNelson Model AV Unit Ventilators 73

General Data

Table 28: Available Unit Ventilator Combinations

Face & Bypass

Control

Valve Control

Basic F & B

AVS AVS AVB AVV AVV AVR AVR

Coil Hand Orientation

LH Heating / RH Cool = E E E E E

RH Heating / LH Cool = F F F F F

Single Coil LH = R R R

Single Coil RH = S S S

LH Both Coils (Only With Controls By Others) = A A A A A

RH Both Coils (Only With Controls By Others) = B B B B B

RH Electric Heat / LH Cool = G G G G

RH Electric Heat, One Coil = D D

Controls

MicroTech II = MT MT MT MT MT MT MT

Digital Ready1 = 17 17 17

Field Mounted Controls By Others = 23 23 23 23 23 23 23

Top Bar Grille Air Discharge, Unit Depth, Adapter Back Arrangement

16-5/8" = AL AL AL AL AL AL AL AL

21-7/8", Partial Adapter Back With Open Pipe Tunnel = AK AK AK AK AK AK AK AK

21-7/8", Full Adapter Back With Closed Pipe Tunnel = AN AN AN AN AN AN AN AN

21-7/8", Full Adapter Back With Closed Pipe Tunnel, Top Duct Intake = AP AP AP AP AP AP AP AP

21-7/8", 2" Stepdown Full Adapter Back With Closed Pipe Tunnel = AM AM AM AM AM AM AM AM

21-7/8", Full Adapter Back With Closed Pipe Tunnel With Solid Back = AB AB AB AB AB AB AB AB

Return Air/Outside Air Options

RA Bottom Front / OA Rear = 22 22 22 22 22 22 22 22

RA Bottom Front With Draft Stop / OA Rear = 30 30 30 30 30 30 30 30

100% RA Bottom Front / No OA Opening / No OA/RA Dampers = 24 24 24 24 24 24 24 24

Power Connection

Box With Switch = GGGGGGGG

Color

Antique Ivory = I I I I IIII

Putty Beige = BBBBBBBB

Soft Gray = GGGGGGGG

Off White = WWWWWWWW

SKU

Standard Delivery = B B BBBBBB

Extended delivery = C C CCCCCC

Product Style

Some coil combinations and configurations may not be available for Digital Ready controls.

3333333

Hydronic Reheat

Electric Heat/Cool

Basic Valve Control

Hydronic Reheat

Electric Reheat

74 McQuay Catalog 1600

General Data

Available Coil Combinations

Table 29: Available Coil Combinations

Face & Bypass Val ve Co nt ro l

Basic Face & Bypass

Electric HEat/Cool

First Position In Airstream Second Position In Airstream AV S AVS AVB AV V AVV AV R AVR

Heating Only

•

••

•

Cooling Only

Heat/Cool

Reheat

65 66 67 68 69 78 79

12 13 Z

V S W 00

G 00

U D E

65 66 67 V S

65 66

V S

G 65 66 67 68 69 78 79

V S W 12

V S W 12 13

68 69 78 79

12 13

Basic Valve Control

Hydronic Reheat

Electric Heat/Cool

•

Hydronic Reheat

Electric Reheat

V S

65 66 67 68 69 78 79

W 65 66

65 66 67 68 69 78 79

G 12 13

V S W

12 13

The “•” mark indicates the coil combination listed to the left is available.

Heating and cooling coil type codes:

Heating Coils:

65 = 1 Row Hot Water Coil 66 = 2 Row Hot Water Coil 67 = 3 Row Hot Water Coil 68 = Low Capacity Steam Coil 69 = High Capacity Steam Coil 78 = Opposite End Drain Low Capacity Steam Coil 79 = Opposite End Drain High Capacity Steam Coil 12 = Low Electric Heat Coil 13 = High Electric Heat Coil 00 = None

Cooling Coils:

U = 2 Row CW/HW 2-Pipe Coil D = 3 Row CW/HW 2-Pipe Coil E = 4 Row CW/HW 2-Pipe Coil V= 2 Row CW Coil S= 3 Row CW Coil W= 4 Row CW Coil G= Direct Expansion Coil Z = None

••

•

AAF-HermanNelson Model AV Unit Ventilators 75

Details & Dimensions

Coil Connections

The dimensional drawings in this section show the location of coil connections for all coil configurations. The drawings are broken into sections as follows:

• “Heat/Cool Units” on page 77

• “Reheat Units” on page 78

• “Heating Only Units” on page 79

• “Cooling Only Units” on page 79

Ta bl e 30 below provides the dimensions that are called out by letter in the drawings.

The following notes apply to all units:

1 All coils have same-end supply and return

connections.

2 Steam coils have a factory-installed pressure

equalizing valve and a 24" (610mm) long pressure equalizing line which terminates in a 1/2" M.P.T. fitting.

3 Steam/hot water connections may be on the same

end as cooling coil connections, but are recommended to be on the opposite end to facilitate

piping. (Must be opposite end when using Microtech II controls.)

4 Cooling condensate drain pan is shipped sloped down

towards the cooling coil connections, but is fieldreversible.

5 Electric heating coil power connections are right end

only. Junction box has 1" (25mm) and 2" (51mm) (trade size) knockouts, 10-1/2" (267mm) from right end of the unit.

6 For limitations with coil combinations see “Available

Coil Combinations” on page 75.

7 Coil connections are 7/8" I.D. (female) and terminate

9" (229mm) from the end of the unit.

8 Steam coils are 1-1/8" female (sweat) connections

and terminate 9" (229mm) from the end of the unit.

9 DX coils (G) have O.D. sweat connections.

Interconnecting tube is supplied by others. See

"Table 32: DX Coil (G) Connection Tubing" below

for correct tubing size.

10 All dimensions are approximate.

Table 30: Coil Connection Dimensions For Lettered Values

Unit Depth

16-5/8 3-3/4 12-1/4 4-7/8 7-3/4 1-5/8 10-1/8 2-3/4 2-7/8 5-5/8 3 5 14

For opposite-end drain steam coils (code 78,79), return (R) is 7-1/4" (184mm) from bottom of unit and H is 2" (51mm) from back of unit.

422 95 311 124 198 41 257 70 73 143 76 127 356

21-7/8 9 17-1/2 10-1/8 13 6-7/8 15-3/8 8 8-1/8 10-7/8 8-1/4 10-1/4 19-1/4

556 229 445 257 330 175 391 203 206 276 210 260 489

A B C D E F G H I J K L

Dimensions

Table 31: Coil Water Capacities (Gallons/Liters)

Unit Series

1 Row Coil

2 Row Coil

3 Row Coil

4 Row Coil

S07 S10 S13 S15

Gal Liter Gal Liter Gal Liter Gal Liter

0.24 0.91 0.29 1.10 0.35 1.32 0.41 1.55

0.41 1.55 0.52 1.97 0.63 2.38 0.74 2.80

0.58 2.20 0.74 2.80 0.92 3.48 1.07 4.05

0.76 2.88 0.96 3.63 1.2 4.54 1.4 5.30

Table 32: DX Coil (G) Connection Tubing

Unit Series:

Suction Line OD:

Liquid LIne OD:

S07 S10 S13 S15

in mm in mm in mm in mm

3/4 19 3/419 7/822 7/822

1/4 6.35 1/4 6 3/8 10 3/8 10

76 McQuay Catalog 1600

Details & Dimensions

Heat/Cool Units

Figure 78. Chilled/Hot Water (2-Pipe) Unit (Coils U, D, E)

Left Hand Right Hand

Air Flow

8-1/2"

(216mm)

= Supply

= Return

13-3/4"

(349mm)

13-3/4"

(349mm)

8-1/2"

(216mm)

Figure 79. Chilled Water and Hot Water Unit (Cooling

Air Flow

Coils S, W, V) (Heating Coils 65, 66, 67)

Cooling (Left Hand) Cooling (Right Hand)

Air Flow

HW Coil

= Supply

(410mm)

11"

(279mm)

= Return

16-1/8"

13-3/4"

(350mm)

(216mm)

8-1/2"

Air Flow

CW Coil

Figure 80. Chilled Water and Steam Unit (Cooling

Coils S, W, V) (Heating Coils 68, 69, 78, 79)

Cooling (Left Hand) Cooling (Right Hand)

8-1/2"

= Supply

= Return

13-3/4"

(350mm)

16-1/8"

(410mm)

(279mm)

11"

Air Flow

Steam

(216mm)

Air Flow

CW Coil

Figure 81. Chilled Water (1st Position) & Electric Heating,

Cooling Coils V, S, W, 5, 6, 7, Heating Coil 12

Cooling (Right Hand)

= Supply

= Return

8-1/2"

(216mm)

13-3/4"

(350mm)

Junction Box

14"

(356mm)

Air Flow

Figure 82. Direct Expansion and Hot Water Unit (Cooling Coil G, Heating Coils 65, 66, 67)

Cooling (Left Hand) Cooling (Right Hand)

= Supply

= Return

= Liquid Line

= Suction Line

16-1/8"

(410mm)

13-3/4"

(349mm)

8-1/2"

(216mm)

Air Flow

(248mm)

9-3/4"

14-1/4"

(368mm)

14-1/4"

(368mm)

8-1/2"

(216mm)

Air Flow

13-3/4"

(349mm)

Figure 83. Direct Expansion (G) and Steam Unit (Cooling Coil G, Heating Coils 68, 69, 78, 79)

Cooling (Left Hand) Cooling (Right Hand)

= Supply

= Return

= Liquid Line

= Suction Line

13-3/4"

(349mm)

11-3/4"

(299mm)

7-1/4"

(184mm)

Air Flow

10-1/8"

14-1/4"

(368mm)

(257mm)

14-1/4"

(368mm)

10-1/8"

(257mm)

Air Flow

11-3/4"

(299mm)

AAF-HermanNelson Model AV Unit Ventilators 77

Details & Dimensions

)

Reheat Units

Figure 84. Chilled Water & Hot Water Unit (Cooling Coils S,

W, V, Heating Coils 65, 66, 67)

Left Hand Right Hand

Air Flow

HW Coil

8-1/2"

(216mm)

= Supply

= Return

13-3/4"

(350mm)

16-1/8"

(410mm)

(279mm)

11"

Figure 85. Chilled Water and Steam Unit (Cooling

Air Flow

CW Coil

Coils S, W, V, Heating Coils 68, 69, 78, 79)

Cooling (Left Hand) Cooling (Right Hand)

Air Flow

Steam

= Supply

= Return

8-1/2"

(216mm)

13-3/4"

(350mm)

16-1/8"

(410mm)

(279mm)

11"

Air Flow

CW Coil

Figure 87. Direct Expansion and Hot Water Unit (Cooling

Coil G, Heating Coils 65, 66, 67)

Cooling (Left Hand) Cooling (Right Hand)

Air Flow

HW Coil

11-3/4"

(299mm)

= Supply

= Return

= Liquid Line

= Suction Line

13-3/4"

(349mm)

16-1/8"

(410mm)

(184mm)

7-1/4"

Air Flow

11"

(279mm)

Figure 88. Direct Expansion and Steam Unit (Cooling Coil

G, Heating Coils 68, 69, 78, 79)

Cooling (Left Hand) Cooling (Right Hand)

= Supply

= Return

= Liquid Line

= Suction Line

11-3/4"

(299mm)

13-3/4"

(349mm)

7-1/4"

(184mm)

Air Flow

11"

(279mm)

16-1/8"

(410mm

Air Flow

Steam

Figure 86. Chilled Water & Electric Heating Unit (Cooling

Coils V, S, W, 5, 6, 7, Heating Coil 12

)

Cooling (Right Hand)

Junction Box

14"

(356mm)

Air Flow

= Supply

= Return

8-1/2"

(216mm)

13-3/4"

(350mm)

78 McQuay Catalog 1600

Details & Dimensions

Heating Only Units

Figure 89. Hot Water Heating Only Unit (Coils 65, 66, 67)

Left Hand Right Hand

Air Flow

= Supply

= Return

13-3/4"

(349mm)

8-1/2"

(216mm)

8-1/2"

(216mm)

13-3/4"

(349mm)

Figure 90. Steam Heating Only Unit (Coils 68, 69, 78, 79)

Left Hand Right Hand

(410mm)

11"

(279mm)

= Supply

= Return

16-1/8"

(410mm)

(279mm)

11"

Air Flow

Cooling Only Units

Figure 92. Chilled Water Cooling Only Unit (Coils V, S, W)

Left Hand Right Hand

Air Flow

= Supply

= Return

13-3/4"

(349mm)

8-1/2"

(216mm)

8-1/2"

(216mm)

13-3/4"

(349mm)

Figure 93. Direct Expansion Cooling Only Unit (Coil G)

Left Hand Right Hand

(410mm)

11"

(279mm)

= Supply

= Return

16-1/8"

(410mm)

(279mm)

11"

Air Flow

Figure 91. Electric Heating Only Unit (Coils 12, 13)

Right Hand

Air Flow

Junction Box

14"

(356mm)

Condensate Drain Connections

Figure 94. Condensate Drain

11"

7/8"(22 mm) O.D. Drain

TX Valve

1-1/2" (38 mm)

5-1/4" (133 mm)

7/8"(22 mm) O.D. Drain

11"

(279 mm)

Condensate

Drain

4-3/4"

(121 mm)

Front View of End Compartment

(Without End Panels)

(279 mm)

Figure 95. Condensate Drain & DX Coil Connections

LL = Liquid Line

5-1/4" (133 mm)

1-1/2" (38 mm)

TX Valve

11"

(279 mm)

SL = Suction Line

7/8"(22 mm)

O.D. Drain

4-3/4"

(121 mm)

Front View of End Compartment

(Without End Panels)

11"

(279 mm)

AAF-HermanNelson Model AV Unit Ventilators 79

Details & Dimensions

16-5/8” (422 mm) Deep Unit Arrangements

Figure 96. Arrangement AL with Open Pipe Tunnel, 16-5/8" Deep

16-5/8"

(422 mm)

1" (25 mm)

10"

(254 mm)

1-3/8" (35 mm)

11-5/8"

(295 mm)

16-5/8"

(422 mm)

4-3/4"

(121 mm)

3" (76 mm)

2-1/2" (64mm)

30-1/8"

(765 mm)

3-1/8"

(86 mm)

7/8" (22 mm) O.D. plastic drain pan - same hand as cooling coil connections - field reversible

10-3/4"

(273 mm)

5-1/4" (133 mm)

(330 mm)

11-5/8"

(295 mm)

(203mm)

13"

1" (25 mm)

2-7/16"

(62 mm)

7-1/4"

(184 mm)

7-3/16" (183 mm)

14"

(356mm)

21"

(533 mm)

(127 mm)

5" (127 mm)

7" (178 mm)

8-5/8" (219 mm)

1-3/4" (45 mm)

7-1/4"

(184 mm)

3-1/2"

(89 mm)

8-7/16" (214 mm)

21"

(533 mm)

30-1/8"

(765 mm)

(330 mm)

(165 mm)

13"

6-1/2"

(330 mm)

4" (102 mm)

13"

Insulation - shaded

1" (25 mm)

Outdoor Air Opening

Air seal

11"

(279 mm)

Table 33: Dimensions A, B, C and Drawing Notes

Dimensions Drawing Notes (①, ✍, etc.)

A B C

1 Bottom entry within 10" x 11-5/8" (254 mm x 295 mm) area 2 Rear entry area 14" x 5" (356 mm x 127 mm).

3 Opening between pipe tunnel & end compartment. 4 Disconnect Switch for main power wiring. 5 Fan motor. 6 Electrical connection box. 7 Slotted kickplate for return air arrangements; partially open kickplate for draftstop arrangements. 8 (4) - 7/8" (22 mm) diameter holes in back for anchoring unit to wall.

9 Accessory panels not included with unit, order separately as an accessory. 10 Controls location (MicroTech II units only). 11 Drain Pan.

S07

S10

S13

S15

Unit Size

in 62 36 43

mm 1575 914 1092

in 74 48 55

mm 1880 1219 1397

in 86 60 67

mm 2184 1524 1702

in 98 72 79

mm 2489 1829 2007

80 McQuay Catalog 1600

Details & Dimensions

Figure 97. Arrangement AL with Closed Pipe Tunnel, 16-5/8" Deep

16-5/8"

(422 mm)

10"

(254 mm)

1-3/8" (35 mm)

1" (25 mm)

11-5/8"

(295 mm)

16-5/8"

(422 mm)

4-3/4"

(121 mm)

3" (76 mm)

2-1/2" (64 mm)

8-7/16" (214 mm)

30-1/8

(765 m

3-1/8"

(86 mm)

10-3/4"

(273 mm)

7/8" (22 mm) O.D. plastic drain pan same hand as cooling coil connections

- field reversible

5-1/4" (133 mm)

1" (25 mm)

2-7/16"

(62 mm)

7-1/4"

(184 mm)

7-3/16"

(183 mm)

14"

(356mm)

21"

(533 mm)

(127 mm)

5" (127 mm)

7" (178 mm)

8-5/8" (219 mm)

3-1/2"

(89 mm)

Unfinished, insulated

13"

4" (102 mm)

Insulation - shaded

21-7/8"

(557 mm)

30-1/8"

(765 mm)

(330 mm)

(165 mm)

13"

6-1/2"

(330 mm)

Outdoor Air Opening

1" (25 mm)

Air seal

(203 mm)

(330 mm)

11-5/8"

(295 mm)

13"

11"

(279 mm)

Closed Pipe

Tunnel

Table 34: Dimensions A, B, C and Drawing Notes

Unit Size

in 62 36 43

S07

mm 1575 914 1092

in 74 48 55

S10

mm 1880 1219 1397

in 86 60 67

S13

mm 2184 1524 1702

in 98 72 79

S15

mm 2489 1829 2007

A B C

Dimensions

1 Bottom entry within 10" x 11-5/8" (254 mm x 295 mm) area 2 Rear entry area 14" x 5" (356 mm x 127 mm).

9 Accessory panels not included with unit, order separately as an accessory. 10 Controls location (MicroTech II units only). 11 Unfinished insulated back. 12 Drain Pan.

Drawing Notes (①, ✍, etc.)

AAF-HermanNelson Model AV Unit Ventilators 81

Details & Dimensions

)

21-7/8" Deep Arrangements

Figure 98. Arrangement AK: Partial Adapter Back With Open Tunnel, 21-7/8" Deep

1-3/8" (35 mm)

10"

(254 mm)

6-1/4"

(159 mm)

4-3/4"

(121 mm)

(556 mm)

8-1/4"

(210 mm)

2-1/2" (64 mm)

21-7/8"

3-1/2"

(89 mm)

5-1/4" (133 mm)

8-7/16" (214 mm)

(533 mm)

21"

3-1/8"

(86 mm)

30-1/8"

(765 mm)

(330 mm)

(165 mm)

6-1/2"

11-5/8"

(295 mm)

21-7/8"

(556 mm)

10-3/4"

(273 mm)

30-1/8"

(765 mm

7/8" (22 mm) O.D. plastic drain pan same hand as cooling coil connections

- field reversible

5-1/4" (133 mm)

11-5/8"

13"

12" (305 mm) Outdoor Air Opening

Air seal

13"

(330 mm)

Insulation - shaded

1" (25 mm)

(295 mm)

(203 mm)

(219 mm)

8-5/8"

1" (25 mm)

2-7/16" (62 mm)

7-3/16" (183 mm)

14"

(356 mm)

21"

(533 mm)

(127 mm)

5" (127 mm)

7" (178 mm)

13-3/4"

(806 mm)

14-1/2"

(368 mm)

1-3/4" (45 mm)

16-1/4"

(413 mm)

Open Pipe Tunnel

Table 35: Dimensions A, C and Drawing Notes

Unit Size

in 62 38

S07

mm 1575 965

in 74 50

S10

mm 1880 1270

in 86 62

S13

mm 2184 1575

in 98 74

S15

mm 2489 1880

Dimensions

A C

Drawing Notes (①, ✍, etc.)

1 Bottom entry within 10" x 11-5/8" (254 mm x 295 mm) area 2 Rear entry area 14" x 5" (356 mm x 127 mm).

9 Accessory panels not included with unit, order separately as an accessory. 10 Controls location (MicroTech II units only). 11 Drain Pan.

82 McQuay Catalog 1600

Details & Dimensions

Figure 99. Arrangement AN: Full Adapter Back With Closed Pipe Tunnel, 21-7/8" Deep

1-3/8" (35 mm)

10"

(254 mm)

6-1/4"

(159 mm)

4-3/4"

(121 mm)

(556 mm)

8-1/4"

(210 mm)

2-1/2" (64 mm)

8-7/16" (214 mm)

1-3/4" (44 mm)

21-7/8"

3-1/8"

(86 mm)

3-1/2"

(89 mm)

5-1/4" (133 mm)

30-1/8"

(765 mm)

30-1/8"

(765 mm)

(330 mm)

13"

6-1/2"

(165 mm)

13"

(330 mm)

7/8" (22 mm) O.D. plastic drain pan same hand as cooling coil connections

- field reversible

27-1/2" (698 mm) Outdoor Air Opening

Insulation - shaded area

1" (25 mm)

Air seal

8-5/8"

(356 mm)

(127 mm)

11-5/8"

(295 mm)

21-7/8"

(556 mm)

10-3/4"

(273 mm)

5-1/4" (133 mm)

1" (25 mm)

2-7/16" (62 mm)

7-3/16" (183 mm)

14"

21"

(533 mm)

5" (127 mm)

7" (178 mm)

11-3/4"

(298 mm)

14"

(356 mm)

4/1/4" (108 mm)

16-1/4"

(413 mm)

Closed Pipe

Tunnel

30-1/8"

(765 mm)

11-5/8"

(295 mm)

(203 mm)

(219 mm)

Table 36: Dimensions A, C and Drawing Notes

Unit Size

in 62 38

S07

mm 1575 965

in 74 50

S10

mm 1880 1270

in 86 62

S13

mm 2184 1575

in 98 74

S15

mm 2489 1880

Dimensions

A C

1 Bottom entry within 10" x 11-5/8" (254 mm x 295 mm) area 2 Rear entry area 14" x 5" (356 mm x 127 mm).

9 Accessory panels not included with unit, order separately as an accessory. 10 Controls location (MicroTech II units only). 11 Drain Pan.

Drawing Notes (①, ✍, etc.)

AAF-HermanNelson Model AV Unit Ventilators 83

Details & Dimensions

Figure 100. Arrangement AP: Full Adapter Back, Top Duct Intake, Closed Pipe Tunnel, 21-7/8" Deep

1-3/8" (35 mm)

3-3/4" (95 mm) Inlet Opening

10"

(254 mm)

6-1/4"

(159 mm)

4-3/4"

(121 mm)

(556 mm)

8-1/4"

(210 mm)

2-1/2" (64 mm)

8-7/16" (214 mm)

1-3/4" (44 mm)

21-7/8"

3-1/8"

(86 mm)

3-1/2"

(89 mm)

5-1/4" (133 mm)

30-1/8"

(765 mm)

30-1/8"

(765 mm)

(330 mm)

(165 mm)

13"

6-1/2"

11-5/8"

(295 mm)

21-7/8"

(556 mm)

7/8" (22 mm) O.D. plastic drain pan same hand as cooling coil connections

- field reversible

10-3/4"

(273 mm)

30-1/8"

(765 mm)

5-1/4" (133 mm)

11-5/8"

Duct Collar 5-1/4" (133 mm) x B

27-1/2" (698 mm) Outdoor Air Opening

Air seal

13"

(330 mm)

Insulation - shaded area

1" (25 mm)

(295 mm)

(203 mm)

(219 mm)

8-5/8"

1" (25 mm)

2-7/16" (62 mm)

7-3/16" (183 mm)

14"

(356 mm)

21"

(533 mm)

(127 mm)

5" (127 mm)

7" (178 mm)

11-3/4"

(298 mm)

14"

(356 mm)

4-1/4" (108 mm)

16-1/4"

(413 mm)

Table 37: Dimensions A, B, C and Drawing Notes

Drawing Notes (①, ✍, etc.)

S07

S10

S13

S15

Unit Size

A B C

62 36 38

1575 914 965

74 48 50

1880 1219 1270

86 60 62

2184 1524 1575

98 72 74

2489 1829 1880

Dimensions

1 Bottom entry within 10" x 115/8" (254 mm x 295 mm) area 2 Rear entry area 14" x 5" (356 mm x 127 mm).

9 Top duct outdoor air opening. 10 Top Duct Collar 11 Accessory panels not included with unit, order separately as an accessory. 12 Controls location (MicroTech II units only). 13 Drain Pan.

84 McQuay Catalog 1600

Details & Dimensions

)

Figure 101. Arrangement AM: Full Adapter Back With 2" Step Down, Closed Pipe Tunnel, 21-7/8" Deep

1-3/8" (35 mm)

10"

(254 mm)

6-1/4"

(159 mm)

4-3/4"

(121 mm)

(556 mm)

8-1/4"

(210 mm)

5-1/4" (133 mm)

2-1/2" (64 mm)

8-7/16" (214 mm)

21-7/8"

3-1/2"

(89 mm)

3-1/8"

(86 mm)

30-1/8"

(765 mm)

Painted

(330 mm)

6-1/2"

(165 mm)

11-5/8"

(295 mm)

21-7/8"

(556 mm)

30-1/8"

(765 mm

7/8" (22 mm) O.D. plastic drain pan same hand as cooling coil connections

- field reversible

10-3/4"

(273 mm)

5-1/4" (133 mm)

11-5/8"

13"

(330 mm)

25-5/8" (651 mm) Outdoor Air Opening

Insulation - shaded area

1" (25 mm)

Air seal

(295 mm)

(203 mm)

1" (25 mm)

2-7/16"

(62 mm)

7-1/4"

(184 mm)

7-3/16" (183 mm)

14"

(356 mm)

(533 mm)

(127 mm)

5" (127 mm)

7" (178 mm)

8-5/8" (219 mm)

2" (51 mm)

28"

(711 mm)

21"

16-1/4"

(413 mm)

Closed Pipe

Tunnel

Table 38: Dimensions A, C and Drawing Notes

Unit Size

in 62 38

S07

mm 1575 965

in 74 50

S10

mm 1880 1270

in 86 62

S13

mm 2184 1575

in 98 74

S15

mm 2489 1880

Dimensions

A C

1 Bottom entry within 10" x 115/8" (254 mm x 295 mm) area 2 Rear entry area 14" x 5" (356 mm x 127 mm).

9 Accessory panels not included with unit, order separately as an accessory. 10 Controls location (MicroTech II units only). 11 Drain Pan.

Drawing Notes (①, ✍, etc.)

AAF-HermanNelson Model AV Unit Ventilators 85

Details & Dimensions

Figure 102. Arrangement AL: With Accessory Top, Open Adapter Back, 21-7/8" Deep

10"

(254 mm)

16-5/8"

(422 mm)

1-3/8" (35 mm)

1" (25 mm)

11-5/8"

(295 mm)

16-5/8"

(422 mm)

4-3/4"

(121 mm)

3" (76 mm)

2-1/2" (64 mm)

8-7/16" (214 mm)

30-1/8"

(765 mm)

3-1/8"

(86 mm)

10-3/4"

(273 mm)

7/8" (22 mm) O.D. plastic drain pan same hand as cooling coil connections

- field reversible

5-1/4" (133 mm)

11-5/8"

(295 mm)

(203mm)

13"

(330 mm)

1" (25 mm)

2-7/16" (62 mm)

7-3/16" (183 mm)

14"

(356mm)

21"

(533 mm)

(127 mm)

5" (127 mm)

7" (178 mm)

8-5/8" (219 mm)

3-1/2"

(89 mm)

Painted 9" Finished Back (Uninsulated)

30-1/8"

21-7/8"

(557 mm)

(765 mm)

(330 mm)

(165 mm)

13"

6-1/2"

(330 mm)

4" (102 mm)

13"

Insulation - shaded area

1" (25 mm)

Outdoor Air Opening

Air seal

11"

(279 mm)

Closed Pipe

Tunnel

Table 39: Dimensions A, B, C and Drawing Notes

Unit Size

in 62 36 43

S07

mm 1575 914 1092

in 74 48 55

S10

mm 1880 1219 1397

in 86 60 67

S13

mm 2184 1524 1702

in 98 72 79

S15

mm 2489 1829 2007

A B C

Dimensions

1 Bottom entry within 10" x 115/8" (254 mm x 295 mm) area 2 Rear entry area 14" x 5" (356 mm x 127 mm).

9 Accessory panels not included with unit, order separately as an accessory. 10 Controls location (MicroTech II units only). 11 9" (229 mm) finished back (painted, uninsulated) 12 Drain Pan.

Drawing Notes (①, ✍, etc.)

86 McQuay Catalog 1600

Details & Dimensions

End Panels

Table 40: 1" (25mm) End Panel Dimensions

Top Vie w

End

View

With No

Cutout

16-5/8" (422mm)

Deep End Panel

16 5/8"

(422mm)

1"(25mm)

27 7/

(708mm)

21-7/8" (556mm)

Deep End Panel

21 7/8"

(556mm)

1"(25mm)

27 7/

(708mm)

28" (711mm)

Deep End Panel

28"

(711mm)

(25mm)

(708mm)

End View

With

2-1/2 x 7"

(64 x

178mm)

Cutout

End View

With

4 x 18"

(102 x

457 mm)

Cutout

End View

With

4 x 22"

(102 x

559mm)

Cutout

End View

With

2 x 5-1/4"

(51 x

133mm)

Cutout

(178mm)

18"

(457mm)

(102mm)

22"

(559mm)

(102mm)

(64mm)

(25mm)

27 7/

(708mm)

(25mm)

27 7/

(708mm)

(25mm)

27 7/

(708mm)

2"(64mm)

(457mm)

(102mm)

(559mm)

4"(102mm)

51/2"(133mm)

(178mm)

18"

22"

(25mm)

(51mm)

(708mm)

27 7/

(708mm)

27 7/

(708mm)

27 7/

(708mm)

(25mm)

22"

(559mm)

4"(102mm)

27 7/

(708mm)

Table 41: 6" (152mm) End Panel Dimensions

Top Vie w

End

View

With No

Cutout

16 5/8"

(422mm)

(152mm)

27"

(686mm)

3" (76mm)

21 7/8"

(556mm)

(152mm)

27"

(686mm)

3" (76mm)

28"

(711mm)

(152mm)

27"

(686mm)

3" (76mm)

AAF-HermanNelson Model AV Unit Ventilators 87

Details & Dimensions

Valve Dimensions

Face & Bypass End Of Cycle Valves

Figure 103. 2-Way EOC Valve

3-11/16"(94mm)

3-1/4"(83mm)

1-1/4"(32mm)

X, Y, Z Dimensions

Connection Cv X Y Z

3/4"(19mm) FNPT 7.0 11-1/16" (43mm) 1-1/16" (23mm) 3-5/8" (92mm)

*1"(25mm) FNPT 7.0 1-7/8" (47mm) 1" (25mm) 31-1/16" (94mm)

Figure 104. 3-Way EOC Valve Modulating Valves

3-11/16"(94mm)

3-1/4"(83mm)

1-1/4"(32mm)

2-9/16"(66mm)

3/4"(19mm)

2-9/16"(66mm)

3/4"(19mm)

Modulating Valves

Figure 105. 2-Way Modulating Valve

4-3/32" 104mm

3-5/32"

80mm

6-13/16"

Figure 106. 2-Way Modulating Valve

4-3/32"

3-5/32"

80mm

104mm

173mm

11/32"

8mm

3-19/32"

80mm

11/32"

8mm

3-15/16"

100mm

2-3/8"(61mm)

3/4"(19mm)

3-1/16"(81mm)

1-7/16"

37mm

1-11/6"

43mm

1-11/6"

43mm

3-5/8"(92mm)

Table 42: Actuator Specifications

Control

Electrical

Stroke

Ambient

2 Position

24 VAC, 50/60 Hz

Power Stroke 9 to 11 seconds

Spring return 4 to 5 seconds

32°F to 125°F (0°C to 52°C)

Table 43: F&B Valve Body Specifications

2-Way Valve 3-Way Valve

Connections

Static Pressure

Close-Off Pressure

Temperature

3/4" FNPT, 1" FNPT 3/4" FNPT

300 psi (2100 kPa) 300 psi (2100 kPa)

13 & 15 psi (90 & 103 kPa) 13 psi (90 kPa)

32°F to 200°F (0°C to 93°C) 32°F to 200°F (0°C to 93°C)

6-13/16"

173mm

Table 44: 2-Way and 3-Way Modulating Valve Dimensions

Val ve S ize

in (DN)

1/2 (DN15) 3 (76) 13/16 (21) 1-9/16 (39) 1-13/16 (46) 8 (203)

3/4 (DN20) 3-7/32 (81) 15/16 (24) 1-5/8 (41) 2-1/8 (54) 8 (203)

1 (DN25) 4-1/8 (119) 1-5/32 (29) 1-3/4 (44) 2-9/16 (65) 9-7/32 (234)

1-1/4 (DN32) 4-23/32 (119) 1-11/32 (34) 2 (51) 2-25/32 (70) 9-7/32 (234)

A B C

N.O./N.C./

Three-Way

2-Way

N.O.

2-Way

N.C.

Three-

Way

Table 45: Actuator Specifications

Control

Electrical

Transformer

Stroke

Operating Temp

Floating Point Modulating

20 to 30 VAC at 50/60 Hz or 24 VDC ± 10%

12 VA (class 2 power source)

29/32 in. (23mm) max. 76 seconds

35 to 250°F (2 to 121°C); 15 psig (103 kPa)

saturated steam

88 McQuay Catalog 1600

Details & Dimensions

Table 46: Modulating Valve Body Specifications

400 psig (2.756 PA) up to 150°F; (66°C)

decreasing to 365 psig; (2,515 kPa) at 248°F

(120°C)

38 psig (262 kPa) Saturated steam at 284°F

35 to 250°F (2 to 121°C); 15 psig (103kPa)

saturated steam

Connections

Static Pressure

Fluid Temperature

Water

Steam

Wall Intake Louvers & Grilles

Louvers are available in both horizontal and vertical blade configurations:

• Horizontal blade construction turns the incoming air to keep moisture from entering. Bottom weep holes drain moisture to the outside.

• Vertical-blade construction provides positive water impingement and entrapment. The bottom lip drains moisture to the outside.

Louvers can be supplied with or without flanges:

• Flanged louvers are typically used for a panel wall finish.

• Unflanged louvers are typically used for recessing into a masonry wall.

A half-inch-square mesh bird screen located on the leaving air side of the louver prevents birds and other small animals from entering. The screen’s strong aluminum mesh is designed to minimize air pressure drops, unlike expanded metal mesh.

Table 47: Louver Specifications

Nominal Air

Unit

S07 750 354

S10 1000 472

S13 1250 590

Flow

CFM L/s L = Length Height Length Height

Louver Dimensions

± 1/16" (± 2mm)

36”

(914mm)

48”

(1219mm)

60”

(1524mm)

10-3/8”

(264mm)

10-3/8”

(264mm)

10-3/8”

(264mm)

Recommended Wall

Opening

36-1/4”

(921mm)

48-1/4

(1225mm)

60-1/4

(1530mm)

10-1/2”

(267mm)

10-1/2”

(267mm)

10-1/2”

(267mm)

Figure 107. Louver With Flange (Horizontal Blades Shown)

Grille (Optional)

Louver Weep Holes In This Area

Horizontal Blade Louver Shown, Vertical Blade Dimensions Are Identical

Bird Screen On Inside

1-1/2" (38mm)

13-3/8"

340 mm

10-3/8"

264 mm

1-1/2" (38mm)

Figure 108. Louver Without Flange (Vertical Blades Shown)

Grille (Optional)

Louver Weep Holes In This Area

Vertical Blade Louver Shown, Horizontal Blade Dimensions Are Identical

Bird Screen On Inside

10-3/8"

264 mm

2-1/4"

57mm

S15 1500 708

72”

(1829mm)

10-3/8”

(264mm)

72-1/4

(1835mm)

10-1/2”

(267mm)

AAF-HermanNelson Model AV Unit Ventilators 89

Details & Dimensions

Ventimatic Shutter Assembly

Notes:

1 Horizontal blade louver shown. Vertical blade louver

also available with Ventimatic shutter.

2 Optional exterior grille matches unit ventilator louver

in material and design. Mounted in wall louver.

Figure 109. Ventimatic Shutter Assembly With Optional Grille

3 Optional interior grille mounting hardware is not

included.

4 Louver leaves seal against plate to prevent air

infiltration.

Table 48: Ventimatic Shutter Assembly Dimensions & Max Air Capacities

Exterior Grille

Width A

inches mm inches mm inches mm

23-3/4 603 24 610 27 686 24-1/4 616 10-1/2 267 1 0 500 236

36-3/4 933 36 914 39 991 36-1/4 921 10-1/2 267 0 1 750 354

47-3/4 1213 48 1219 51 1295 48-1/4 1225 10-1/2 267 2 0 1000 472

59-3/4 1518 60 1524 63 1600 60-1/4 1530 10-1/2 267 1 1 1250 590

71-3/4 1822 72 1829 75 1905 72-1/4 1835 10-1/2 267 0 2 1500 708

Louver

Width B‘

Interior Grille

Width C

Recommended Wall Opening

For Louver

Length Width

inches mm inches mm

Max Number of Ventimatic

Shutters To Mount On

Standard Louver

24” (610mm)

Shutter

36” (914mm)

Shutter

Ventimatic

Shutter(s) Max

Air Capacity

inches mm

90 McQuay Catalog 1600

Details & Dimensions

Sink & Bubbler Cabinet

Notes:

1 Sink top is one-piece, stainless steel construction with

sound-deadening coating on the under side. Front edge has raised lip continuously from end to end.

2 Sliding doors available in decorator colors.

Figure 110. Top View - Single Bowl & Bowl With Bubbler

17-7/8" 454mm

9-5/16"

228mm

Figure 111. Front & End Views

1/8" (3mm)

16" 392mm

11- 1/8"

283mm

Faucet

Bubbler

3 Sink and bubbler basin drains equipped with 1-1/2"

O.D. tail pieces, all chrome plated brass.

4 Sink faucet and bubbler valve are shipped loose for

field installation by the installing contractor.

5 Sink and bubbler top is designed to project 1/16"

higher and 3/16" deeper than the adjoining cabinets, unit ventilator or end panels.

12" 25mm

9-1/8" 232m

427mm

16-13/16"

17-7/8" 454mm

9-5/16"

228mm

427mm

16-13/16"

16" 392mm

21" 533mm

11- 1/ 8"

283mm

16-13/16"

427mm

Bubbler

(4) 7/8" (22mm) Dia.

26"

660mm

25mm

3"(76mm)

Knockouts In Back For Anchoring To Wall

1-9/16"

40mm

21-7/8" (556mm)

16-13/16"(427mm)

21-7/8"(556mm) Deep Cabinet

Right End View

48" (1219mm)

Front View

23"

584mm

127mm

Door Lock (Optional)

2-1/2"

64mm

21-7/8" (556mm)

16-13/16"(427mm)

3"(76mm)

30-1/8"

765mm 13-1/2" 765mm

6-1/2"

165mm

21-7/8"(556mm) Deep Cabinet

With Radiation Bar Grille

Radiation Bar Grille

23"

584mm

127mm

30-1/8" 765mm

28-1/8"

714mm

16-13/16"(427mm) Deep Cabinet

Right End View

21-7/8" (556mm)

16-13/16"(427mm)

3"(76mm)

21-7/8"(556mm) Deep Cabinet

With Draftstop Bar Grille & Damper

Draftstop Bar Grille & Damper

23"

584mm

127mm

AAF-HermanNelson Model AV Unit Ventilators 91

Details & Dimensions

Filler Sections & Utility Compartment

Filler sections are furnished in 18" and 24" lengths. They are provided with enough hardware to assemble one right hand and one left hand filler having a combined

after cutting is 3". The filler section may be used between a cabinet and the wall, between a unit and the wall, between a unit and cabinets, or between cabinets.

length of 18”/24" or less. The minimum length of one filler

Figure 112. Wall Filler Section With Painted Metal Or Laminate Top

Painted Metal Top

Attach to wall,

left or right end.

Front

Kickplate

Front End Cap

Figure 113. Corner Filler Sections

Attach to unit

ventilator, storage

cabinet right.

Top End Cap

Attach to unit ventilator or utility cabinet right or left end.

Painted Metal Top

Support Strip

Attach to wall,

left or right end.

Front Kickplate

Laminate Top

Mounting Angle for attaching top to unit ventilator, utility cabinet and back wall.

Side Panel Adapter for attaching top to storage cabinet.

Attach to unit ventilator or storage cabinet right or left end.

Front End Cap

Laminate Top

Support Strip

Attach to wall

Figure 114. 12" Utility Compartment

Dim. A MM Dim. B MM

16-5/8 442 3 76

21-7//8 556 5-1/4 133

30"

762mm

3" 76mm

12"

305mm

3" (76mm)

Corner Post

Kickplate

1" 25mm

28"

660mm

14" 356mm

Attach to wall

Corner Post

Kickplate

12"

305mm

12"

305mm

92 McQuay Catalog 1600

Details & Dimensions

Shelf Storage Cabinets

Figure 115. Shelf Storage Cabinets, Front View

1”

25mm

24, 36, 48 & 60” open

(610, 914, 1219 & 1524 mm)

25mm

1”

72, 84, 96, 108 & 120” open (1829, 2134, 2438, 2743 & 3048mm)

10” 254mm

762mm

13-1/2” 343mm

6-1/2” 165mm

1-9/16” (40mm)

Removable end panels

Shelf adjustable in 2” (51mm) increments

4-7/8” (22mm) diameter knockouts in back for anchoring to wall

Front skirt with air inlet for radiation style cabinet

Front skirt for standard and draftstop style cabinet

Figure 116. Shelf Storage Cabinets, Front View

1”

25mm

Front skirt with air inlet for radiation style cabinet

24, 36, 48 & 60” open

(610, 914, 1219 & 1524 mm)

Door lock (optional)

Removable end panels

Sliding doors

Front skirt for standard and draftstop style cabinet

30”

762mm

30”

1”

25mm

Shelf adjustable in 2” (51mm) increments

Removable end panels

Front skirt with air inlet for radiation style cabinet

72, 84, 96, 108 & 120” open (1829, 2134, 2438, 2743 & 3048mm)

Door lock (optional)

Removable end panels

Front skirt with air inlet for radiation style cabinet

Door pull

4-7/8” (22mm) diameter knockouts in back for anchoring to wall

Front skirt for standard and draftstop style cabinet

Sliding Doors

10” 254mm

30”

762mm

13-1/2” 343mm

6-1/2”

165mm

1-9/16” 40mm

30”

762mm

Figure 117. Right End View - 16-5/8” (442 mm) Deep Shelf Storage Cabinets With 11-1/2” (292mm) Shelf & Metal Top

30”

762mm

686mm

3” (76mm)

13-11/16” (348mm)

27”

16-5/8” (442mm)

Piping

area

2-15/16”

(75mm)

23”

584mm

5” (127mm)

30”

762mm

686mm

3” (76mm)

16-5/8” (442mm)

13-11/16” (348mm)

27”

Piping

area

2-15/16” (75mm)

Radiation bar grille

23”

584mm

5” (127mm)

30”

762mm

686mm

3” (76mm)

16-5/8” (442mm)

13-11/16” (348mm)

27”

Piping

area

2-15/16” (75mm)

Draftstop bar grille & damper

23”

584mm

5” (127mm)

Standard Cabinet Cabinet With Radiation Bar Grille Cabinet with DraftStop Bar Grille & Damper

AAF-HermanNelson Model AV Unit Ventilators 93

Details & Dimensions

Figure 118. Right End View - 21-7/8” (556 mm) Deep Shelf Storage Cabinets With 13-1/2” (343mm) Shelf With Metal Top

21-7/8” (556mm)

16-1/16” (408mm)

5-13/16” 148 mm

21-7/8” (556mm)

16-1/16” (408mm)

5-13/16” (148)

Radiation bar grille

21-7/8” (556mm)

16-1/16” (408mm)

5-13/16”(148 mm)

Draftstop bar grille & damper

30”

762mm

686mm

3” (76mm)

27”

Piping

area

23”

584mm

5”

127mm

30”

762mm

27”

686mm

3” (76mm)

Piping

area

23”

584mm

5”

127m

30”

762mm

27”

686mm

3” (76mm)

Piping

area

23”

584mm

5” (127mm)

Standard Cabinet Cabinet With Radiation Bar Grille Cabinet with DraftStop Bar Grille & Damper

Figure 119. Right End View - 16-5/8” (442 mm) Deep Shelf Storage Cabinets With 11-1/2” (292mm) Shelf With Laminate Top

27”

16-5/8” (442mm)

13-11/16” (348mm)

Piping

area

2-15/16” (75mm)

Draftstop bar grille & damper

23”

584mm

30”

762mm

686mm

16-5/8” (442mm)

13-11/16” (348mm)

27”

Piping

area

2-15/16”

(75mm)

23”

584mm

30”

762mm

686mm

16-5/8” (442mm)

13-11/16” (348mm)

27”

Piping

area

2-15/16” (75mm)

Radiation bar grille

23”

584mm

30”

762mm

686mm

3” (76mm)

5” (127mm)

3” (76mm)

5” (127mm)

3” (76mm)

5” (127mm)

Standard Cabinet Cabinet With Radiation Bar Grille Cabinet with DraftStop Bar Grille & Damper

Figure 120. Right End View - 21-7/8” (556 mm) Deep Shelf Storage Cabinets With 13-1/2” (343mm) Shelf With Laminate Top

21-7/8” (556mm)

16-1/16” (408mm)

Piping

area

5-13/16” (148)

Radiation bar grille

23”

584mm

5”

127mm

30”

762mm

686mm

3” (76mm)

16-1/16” (408mm)

27”

21-7/8” (556mm)

5-13/16”(148 mm)

Draftstop bar grille & damper

Piping

area

23”

584mm

5” (127mm)

30”

762mm

686mm

3” (76mm)

27”

21-7/8” (556mm)

16-1/16” (408mm)

Piping

area

5-13/16” 148 mm

23”

584mm

5”

127mm

30”

762mm

27”

686mm

3” (76mm)

Standard Cabinet Cabinet With Radiation Bar Grille Cabinet with DraftStop Bar Grille & Damper

94 McQuay Catalog 1600

Details & Dimensions

89 mm

Finned Tube Radiation Cabinets

Figure 121. Slope-Top Radiation Cabinet

5-3/8"

137mm

Section “X-X” Internal

Joggle-Joiner

12, 20 & 24"

2-7/8"

73m

305, 508 & 610mm

152mm

2-7/8"

73 mm

4" min

102 mm

Floor

Tinnerman

nut

Detail of enclosure’s

bottom mounting clip

51mm

1-1/4" 89 mm

Fin

Mounting Channel Detail

Figure 122. Flat-Top Radiation Cabinet

5-3/8"

137mm

Section “X-X” Internal

Joggle-Joiner

Enclosure

3/8" (10mm) max screw (by others)

Bracket

Enclosures are available in 1 to 8-foot lengths and 6-inch increments

Enclosure

Height

Cradle type

expansion

bracket

2” (51mm)

Mounting

Channel

Enclosures are available in 1 to 8-foot lengths and 6-inch increments

Full height back plate

Second

row

bracket

3-1/2”

89 mm

Outside corner

12”

305 mm

Bare

tube

support

9”

229 mm

Inside corner

305 mm

Door

6 x 6”

152 x

152 mm

12” wide enclosure

with access door

3-1/2”

89 mm

12”

12” wide end cap

with access door

3-1/2, 5 & 7-1/2”

89, 127 & 191 mm

End

Trim Strip

cap

Damper

knob

9”

229 mm

Inside corner

12”

305 mm

12” wide enclosure

with access door

152 mm

3-1/2”

89 mm

End cap

12”

305 mm

Door 6 x 6” 152 x

12” wide end cap

3-1/2, 5 & 7-1/2”

89, 127 & 191 mm

Trim Strip

with access door

12, 20 & 24"

Floor

305, 508 &

610mm

Slide

ClosedOpen

Grille Detail

Enclosure

1-1/4" 89 mm

51mm

3/8" (10mm) max screw (by others)

Mounting Channel Detail

3-1/2”

89 mm

Outside corner

2” (51mm)

Mounting

Channel

AAF-HermanNelson Model AV Unit Ventilators 95

Wiring Diagrams

Typical MicroTech II Wiring Diagrams

Figure 123. Typical MicroTech II Wiring Diagram

96 McQuay Catalog 1600

Wiring Diagrams

Typical Wall Sensors Diagram

Figure 124. Wall-Mounted Temperature Sensor Wiring for Wall Sensor

Power & Control Field Wiring

Figure 125. External Input Wiring Examples with or without Daisy Chaining of Units

Unit Ventilator #1

Connector

GND

Comm

BI-6 BI-5 BI-4 BI-3

896 908A 907A 906A 905A

904A

Wire

Caps

Shield

Unit Ventilator #2

Connector

GND

Comm

BI-6 BI-5 BI-4

BI-3

Unit Ventilator #3

Connector

GND

Comm

BI-6 BI-5 BI-4

BI-3

896 908A 907A 906A 905A 904A

Wire

Caps

Wire

Caps

Shield

Additional Units

External Input

Option 4 Device

(by Others)

WSHP

Boilerless System

(low temp switch)

External Input

Option 3 Device

(by Others)

Ventilation Lockout

(default) or

Exhaust Interlock

External Input

Option 2 Device

(by Others)

Remote Shutdown

Factory Wiring

Field Wiring (by Others)

External Device (by Others)

External Input

Option 1 Device

(by Others)

Unoccupied

AAF-HermanNelson Model AV Unit Ventilators 97

Wiring Diagrams

Figure 126. External Output Wiring - Single Unit

Unit Ventilator

UVC

xBO-2

Comm

xBO-1

BO-6 BO-6

Comm

24vac Supply

24vac Comm

Connector

601A 602A 603A 604A 605A 606A 608A 610A

Wire

Caps

Shield

Factory Wiring

Field Wiring (by Others)

External Device (by Others)

External Output

Option 1 Device

(by Others)

Lights On/Off

Signal

Motorized Water

Valve Open/Close

External Output

Option 2 Device

(by Others)

Fault Indication

Pump Restart

Figure 127. External Output Wiring - Multiple Units Shown

Unit Ventilator #1

Connector

UVC

XBO-2 Comm

XBO-1

BO-6 BO-6

Comm

24vac Supply 24vac Comm

Unit Ventilator #2

Connector

UVC

XBO-2 Comm

XBO-1

BO-6

Comm

24vac Supply

24vac Comm

Unit Ventilator #...X (last unit)

Connector

UVC

XBO-2 Comm

XBO-1

BO-6

Comm

24vac Supply

24vac Comm

601A 602A 603A 604A 605A 606A 608A 610A

Wire

Caps

Wire

Caps

Wire

Caps

Shield

Additional Units

Signal

External Output

Option 3 Device

(by Others)

Auxiliary Heat

Signal

Exhaust Fan

On/Off Signal

External Output Option 2 Device

(by Others)

Fault Indication

Pump Restart

Signal

Factory Wiring

Field Wiring (by Others)

External Device (by Others)

98 McQuay Catalog 1600

Wiring Diagrams

Figure 128. Split-System Condensing Unit Signal Wiring

Split System Unit Ventilator

UVC

BO-9

Connector

Wire

Caps

607A

Comm

24vac Supply 24vac Comm

608A 610A

Shield

Factory Wiring

Field Wiring (by Others)

External Device (by Others)

Typical Digital Ready Wiring Diagram

Figure 129. Typical Digital Ready Wiring Diagram

Condensing Unit

On/Off Signal

(24vac)

AAF-HermanNelson Model AV Unit Ventilators 99

Wiring Diagrams

Typical Controls By Others Wiring Diagram

Figure 130. Typical Wiring Diagram For Units With Controls By Others

100 McQuay Catalog 1600

McQuay AVR User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual

Introduction

AAF-HermanNelson Classroom Unit Ventilators

Low Installation Costs

Quiet Operation

The Right Amount of Fresh Air and Cooling

Precise Temperature and Dehumidification Control

Low Operating Costs

Easy To Maintain, Modular Design

Built To Last

MicroTech II Control For Superior Performance, Easy Integration

The Model AV Floor Unit

Features & Benefits

Quiet Operation With Our GentleFlo Delivery

The Right Amount of Fresh Air and Cooling

Economizer Operation

Part-Load Variable Air Control

Demand Control Ventilation

Precise Temperature and Dehumidification Control

Draw-Thru Design For Even Discharge Temperatures

Face & Bypass Design For Better Temperature and Humidity Control

Why Blow-Thru Designs Don’t Measure Up

Passive Dehumidification (Optional)

Increased Coil Freeze Protection

Active Dehumidification (Reheat)

Low Installation Costs

Perfect For Both New & Retrofit Applications

Built In Flexibility

Controls Flexibility

Low Operating Costs

MicroTech II Control Options Further Reduce Operating Costs

Easy To Maintain

Modular Fan Deck

Heavy-Duty Discharge Grille

Easy Motor Removal

Tamper-Resistant Fasteners

Sectionalized Access Panels And Doors

Single-Filter Design

Built To Last

Heavy Duty Frame Construction

Rugged Exterior Finish

Durable, Energy Efficient Fan Motors

Durable Damper Design

MicroTech II Controls

MicroTech II Controls For Superior Performance, Easy Integration

Three Control Levels

A Wide Variety of Input, Output & Alarm Data Points Available

Control Modes and Functions

Occupancy Modes

Economizer Modes

Night Purge Mode

Freeze Prevention Mode

Emergency Heat Mode

External Input Functions

External Output Functions

Demand-Controlled Ventilation (Optional)

Advanced Control Options

Part Load Variable Air Control

Active Dehumidification Control (Reheat)

DX Split System Control

Passive Dehumidification Control

System Components

Unit Ventilator Controller

Local User Interface

Optional Communication Modules

Sensors

Actuators

Optional Time Clock For Stand-Alone Operation

ServiceTools™

Accessories

Wall Louvers & Grilles

Ventimatic™ Shutter Room Exhaust Ventilation

Ventimatic Installation

Storage Cabinets, Sink & Bubbler

Storage Cabinets

Sink & Bubbler Cabinet

End Panels, Filler Sections & Sub-Bases