Auto-Zone Control Systems Zoning Design User Manual

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Table Of Contents

How Auto-Zone Works ..........................................................................................................5

Why Should I Use Auto-Zone?..............................................................................................6

What Is Unique About Auto-Zone? ....................................................................................6-8

Zoning Systems Versus True VAV Systems .......................................................................... 9

Basics Of Designing A Zoning System................................................................................ 10

Design Considerations ................................................................................................... 11-12

Zoning Design Procedures.............................................................................................13-21

System Installation .........................................................................................................22-26

Application Notes ................................................................................................................27

Table Of Figures & Tables

Figure 1-1: Auto-Zone Plus System Overview .................................................................... 5

Figure 1-2: Zones Affected By Outdoor Load...................................................................13

Figure 1-3: Zone Layout With External Zones Only ......................................................... .14

Figure 1-4: Zones With North And South Exposures ....................................................... .14

Figure 1-5: Zoning And Constant Volume Units ................................................................14

Figure 1-6: Round Bypass Damper.................................................................................. .16

Figure 1-7: Rectangular Bypass Damper & Kit ................................................................ .16

Figure 1-8 Preferred Sensor Location ..............................................................................1 7

Figure 1-9: Acceptable Sensor Location ........................................................................... 17

Figure 1-10: Least Desirable Sensor Location .................................................................... 17

Figure 1-11: Pressure Dependent Damper .........................................................................1 8

Figure 1-12: Pressure Independent Damper.......................................................................1 8

Figure 1-13: WattMaster Communications Wire ................................................................. 23

Figure 1-14: Auto-Zone Basic System Communications Loop Wiring ................................2 4

Figure 1-15: Auto-Zone Plus System Communications Loop Wiring .................................. 24

Figure 1-16: Transformer & Wire Sizing Considerations.....................................................26

Table 1-1: Round Damper Selection Data.......................................................................... 19

Table 1-2: Rectangular Damper Selection Data .................................................................2 0

How Auto-Zone Works

Zoning Design Guide

The Auto-Zone control system converts single-zone constant volume rooftop packaged or split system HVAC units into variable air volume/variable temperature multiple zone systems. The microprocessor based Zone Manager calculates the heating and cooling requirements for each zone based on real time information received from each Zone Controller/Damper. The Zone Manager then directs the HVAC unit to provide the appropriate amount of heating, cooling, and ventilation to satisfy each zone’s requirements. A bypass damper controlled, by a static air pressure sensor, modulates a bypass damper to maintain constant duct pressure.

The Auto-Zone system uses a unique 3 tier approach to controlling the system:

• Voting Zones

• System Demand

• Priority

This 3 tier system works in an integrated fashion to maintain proper control of the equipment and effective control of comfort in the zone.

First the zone must initiate a vote to the HVAC unit. This occurs when a zone becomes more than 1 degree off setpoint. At this time a vote is placed for heating or cooling. Next the controller evaluates the total cooling demand or heating demand within the entire building to see which requirement is more critical. Finally, the system looks for any priority conditions, which would take precedence over other zones. All three of these elements working together provide accurate and stable control of comfort.

Additional control features are taken into account to provide a very effective control of the system. Some of these include priority override, supply air temperature limits, outside air temperature lockouts, and min./max. control over damper position.

Substantial savings can be realized using the Auto-Zone Zoning system instead of having to install multiple rooftop units to accommodate multiple zone requirements. The Auto-Zone Zoning system is versatile and can be used with any packaged roof top unit or split system. It controls a variety of terminal unit functions including single duct pressure dependent, pressure independent, series fan and parallel fan terminals.

CONNECT TO OTHER ZONE MANAGERS

120/9 VAC

TRANSFORMER

AVOID

DIRECT

SUNLIGHT

NETWORK COMM LOOP

AC LINE VOLTAGE

COMPUTER (OPTIONAL)

RemoteLink

CONTROLS

REMOTE LINK

(OPTIONAL MODEM)

2 CONDUCTOR

24 GA.

OUTSIDE AIR SENSOR

24 VAC

GROUND

COMMLINKII

CONTROLS

COMM LINK II

INTERFACE

( OPTIONAL )

CONTROL CABLE

SUPPLY AIR

TEMPERATURE

SENSOR

2 CONDUCTOR

ZONE MANAGER

LOCAL COMM LOOP

120/24 VAC

TRANSFORMER

24 GA.

SYSTEM MANAGER

FAN

MIXED

AIR

OUTSIDE AIR

EXHAUST AIR

RETURN AIR

MODULATING

3 CONDUCTOR

24 GA.

BYPASS DAMPER

STATIC PRESSURE SENSOR & PICKUP TUBE

2 CONDUCTOR

24 GA.

RETURN AIR SENSOR

CONNECT TO OTHER ZONE CONTROLLERS OR CV UNITS

SUPPLY AIR DUCT

MODULATING

DAMPER

ZONE

CONTROLLER

SYSTEM

MANAGER

ZONE 1

TEMPERATURE SENSOR

MODULATING

DAMPER

ZONE

CONTROLLER

WARMER

NORMAL

COOLER

OVR

ZONE 2

TEMPERATURE SENSOR

W/OVERRIDE AND SETPOINT ADJUST

UP TO 16 ZONES

Figure 1-1: Auto-Zone Plus System Overview

Auto-Zone Systems 5

Zoning Design Guide

Why Should I Use Auto-Zone?

Auto-Zone is a proven system with a long history of successful installations. Our systems have been refined over the years with the help of feedback from people in the field who work and live with these systems on a daily basis. Our success is greatly due to the fact that we have implemented changes and enhancements based

on real world experience not from tinkering with equipment in an isolated lab environment. This real world approach provides engineers, contractors, and end users with a zone control system that is efficient, reliable, and most importantly, keeps the customers comfortable!

What Is Unique About Auto-Zone?

Auto-Zone is unique because it has many features not found on other systems. These features include

Non-Proprietary Design

Auto-Zone will work on any manufacturers HVAC equipment that will accept a standard thermostat connection. This protects the end user from being locked in to one source for service and support. In addition, AutoZone Systems include very comprehensive documentation, which was written in a format specifically for a “non-controls technician”. Because the manuals are so user friendly, it prevents the end user from being “locked-in” to one contractor for service. Any new contractor needs only a copy of the system manual to have as much technical information as any previous contractor.

Pre-Engineered Software

System design, software, and documentation has already been done for you. This eliminates the costly expense usually associated with conventional DDC systems, making the Auto-Zone system more competitive and easier to install and operate.

One System for Zoned or Single Zone Systems

Not only does Auto-Zone provide a networked zone control system for one or multiple zoned HVAC units, you can also connect individual single zone units to the system eliminating the need to use programmable thermostats.

Easy to Configure

Since Auto-Zone components are grouped into packages, configuring a system has been simplified. This reduces the chance of ordering errors and makes system layout effortless!

User Friendly Set Up

Since the Auto-Zone comes with menu driven, fill in the blank programming, system setup is simple. The system manual takes you step by step through the set up process. Default parameter values are programmed into permanent memory so the system can be operational at start-up. Specialized training is not required.

6 Auto-Zone Systems

Zoning Design Guide

True Network Communications

The Auto-Zone uses a three wire, RS-485 loop for communication between all controllers in the system. This provides a very reliable form of communication with flexibility of installation. The loop can be wired in a “daisy chain” or “star” configuration. Many other zoning systems utilize “home run” wiring that requires all communication cables to be brought back to a central point adding additional cost to the project and complicating wiring.

High Integrity Communications

Many communicating control systems are susceptible to electrical interference. One major manufacturer of zoning systems recommends that their communication cable should not be strapped to conduit because of potential interference. The Auto-Zone Systems have a communication bus that is almost immune to any noise problems that may be found in most commercial facilities.

Microprocessor Controllers

All controllers in the Auto-Zone have an on board microprocessor. This is what gives the Auto-Zone its powerful features and capabilities not found in other systems.

Stand Alone Systems

All Auto-Zone Systems are true stand-alone and do not require a computer to operate. Unit controllers maintain their own 7 day time clock, 365 day holiday scheduling, and setpoints within each controller.

Menu Driven Operators’ Interface

All Auto-Zone systems have an operators’ keypad and display terminal. This gives you access to system status and parameter values without the need for a computer. The 4 line by 20 character display is backlighted making it easy to read even in low light environments. Menu driven programming makes the system extremely user friendly. In addition, the interface panel is password protected to keep unauthorized users from accessing the system.

Communications Via Optional Modem

The Remote Link is used for achieving remote communications with the Auto-Zone system. It connects to the

CommLink II communications interface and a local phone line. With the Remote Link, the Auto-Zone system can be monitored and controlled from a remote location, using a computer and the ZoneView AZ or Plus software packages.

Memory Backup

Instead of batteries, which have to be replaced, AutoZone utilizes super capacitors to provide power for memory backup during power outages. The major advantages to this approach is that super capacitors are more reliable than batteries and they recharge in a matter of seconds instead of hours. T ypical memory backup is good for a minimum of 10 days.

Modulating, Heavy Duty Actuators with Real Time Feedback

All Auto-Zone actuators utilize true modulating control unlike many systems, which are two position. This gives the system-improved control, which translates, to better comfort levels. Our actuators are also rated for 2-½ million cycles, making our actuators some of the most reliable in the industry. One other critical feature is the real time feedback. Many other systems have no feedback at all. They blindly estimate the travel time of their actuator, which, in the real world, is not a very repeatable estimate. To help correct the problems inherent with this approach, they recycle all the actuators in the system once or twice a day . They may save a few dollars by not including feedback but they sacrifice system performance. Not so with Auto-Zone.

Commercial Grade – Insulated Round Zone Dampers

Auto-Zone only uses commercial grade zone dampers, not cheap, flimsy, “light commercial” or “residential” style dampers like many other manufacturers. Our round damper is ARI certified and comes from the factory fully insulated. Why? When many zone dampers are installed they are improperly insulated or not insulated at all. This can cause problems with the damper “sweating” from condensation. With factory insulated zone dampers, we eliminate a common problem for the contractor while insuring the end user will not have problems with condensation dripping down onto the ceiling.

Auto-Zone Systems 7

Zoning Design Guide

What Is Unique About Auto-Zone?

Rectangular Dampers

Auto-Zone uses only top of the line, aluminum air foil rectangular control dampers. No other zone system on the market today utilizes a damper of this quality and performance!

Patented Flush Mount Room Sensors

Our flush mount room sensors are so unique, they are patented (U.S. Patent No. 4,659,236). Even though part of the sensor is recessed into the wall to provide an attractive yet tamper proof flush mounting, internal wall temperatures do not influence the sensor. A special plate on the face of the sensor accurately senses space temperature. Even though the attractive off white plastic housing is a preferred color, the sensor housing can be painted or wallpapered to blend with room decor without affecting sensor performance. The sensors are offered in four different configurations:

• Sensor

• Sensor w/override

hundreds. ZoneView is not copy protected so it can be installed on multiple PC’s’ without additional expense. Just some of its many features include but are not limited to:

• Pre-designed status screens for all controllers

• Alarm dial out capability

• Programming of all system parameters

• Trend logging to Excel™ spreadsheets

• Alarm Handling

• Custom graphics capability

• Sensor w/setpoint adjustment

• Sensor w/setpoint adjustment & override

Modular Connections

Many Auto-Zone auxiliary devices are connected to the controllers via modular plugs like the ones used on telephones. This simplifies installation and eliminates the possibility of wiring errors. The devices, which utilize this method, are damper actuators for zone and bypass control, auxiliary relay boards, and static pressure/air flow sensors. There is one interesting side note about the auxiliary relay board and airflow sensors. These devices are typically used on the zone controllers in the Auto-Zone Basic & Plus systems. When the system is powered up, it automatically looks to see if these devices are connected to the controller. If they are, the controller automatically reconfigures itself to utilize these devices and activates the appropriate set up screens back at the operators interface. Pretty neat don’t you think!

FREE! Windows™ Graphics Software

Each Auto-Zone system can be monitored on site or remotely using a PC and our ZoneView Plus™ Windows 98 software. This full-featured package is very user friendly and can be used to monitor one system or

Open Protocol System

Auto-Zone is an open protocol based system allowing other manufacturers to develop direct interfaces to the communications loop. This gives you the ability to integrate the Auto-Zone system into products from other vendors. Our engineering staff will be glad to assist any vendor in this process.

8 Auto-Zone Systems

Zoning Design Guide

Zoning Systems Versus True VAV Systems

General

Even though there are some similarities between zone control systems and Variable Air Volume (VAV) systems, there are some major differences. In many cases systems will be called VAV when in fact they are really a zoning system or are referred to as a zoning system when they are really a VAV system. Always make sure that you do not try to adapt a zoning system to a VAV design system. Understanding the differences will help you to prevent misapplication of the Auto-Zone zoning system. In the paragraphs that follow we will try to explain the differences, advantages and disadvantages of each and explain their operation.

V AV Systems

These systems consist of an HVAC unit that is generally a cooling only unit and VAV terminal units located in the downstream ductwork that are used to control the amount of constant temperature air delivered to the various building zones. Sometimes the HV AC unit may have gas or electric heat, but it is typically sized and applied for morning warm-up purposes. The HV AC unit is designed to vary the volume of air that is supplied to the duct system by using either inlet vanes or an electronic variable frequency drive. These devices modulate to control the air flow through the supply fan in response to the static pressure in the duct system. VAV systems typically use high velocity VAV terminal units to distribute the air to the zones. As the various VAV terminal units in the different zones open and close to supply the constant temperature air to the spaces, the HVAC unit varies the volume of constant temperature air based on the static pressure in the ductwork. The HV AC unit is designed to maintain a constant cold supply air temperature regardless of the air flow volume in the system. The HVAC unit cycles it’s cooling stages to maintain a constant predetermined supply air temperature. It typically runs continuously based on a schedule. For perimeter zones requiring heat, reheat coils (electric or hot water) located in the terminal units are used to supply heated air to the space. Many times fan powered terminal boxes are used and in many cases also incorporate electric or hot water heating coils to provide perimeter zone heating. In summary a true V AV system uses a variable volume fan supplying constant temperature air to the system with variable volume terminal units used to control the volume of constant temperature air delivered to the space. Generally these systems use pressure independent damper control.

Auto Zone Systems

The Auto-Zone zoning system is completely different in operation and design from the VAV system previously discussed. One of the major differences between the zoning system and a true VAV system is that the HVAC unit used on a zoning system utilizes a constant volume fan. Air volume control of the zoning system is achieved by bypassing air from the HVAC unit supply duct back into the HVAC unit return air duct on the unit inlet. This bypass air is controlled based on a static pressure sensor located in the supply air duct downstream of the unit supply air discharge. The bypass damper modulates open and closed based on the static pressure in the duct. The temperature at the HV AC unit dischar ge varies in relation to the demand from the zones. Typically the HVAC units used for the zoning system will have both heating and cooling capabilities. The fan supplies a constant volume of cold or hot air to the duct system and which is fed to the individual zones by modulating zone dampers. Each zone controller relays its heating or cooling demand to the HVAC unit controller. The HVAC unit controller determines its mode of operation (heating, cooling or vent mode) depending on the demand from the zone controllers. The unit controller utilizes a voting system to determine the correct mode of operation. Each zone controller determines (based on its heating and cooling setpoints) whether or not to use the air being supplied by the HVAC unit. For example, one of the zones is calling for cooling when the temperature in the duct is above the zones cooling setpoint. This zone will move to its minimum cooling position to prevent warm air being introduced into the space. With the zoning system the zone dampers are generally pressure dependent. Pressure independent operation is available but is not very common. Reheat and/or fan powered terminal units can be used but aren’t commonly part of the typical zoning system.

Conclusion

In many cases VAV systems go over budget because of the increased cost of a VAV, HVAC unit and the expensive VAV controls associated with the system. Many times the system can be redesigned to a zoning system using Auto-Zone controls with a significant cost savings and equal or better performance and comfort than the VAV system would provide. Be sure to follow the instructions in this design guide for your zoning system.

Auto-Zone Systems 9

Zoning Design Guide

Basics of Designing A Zoning System

This is a summary of the key items you need to consider for the design and layout of a successful zoning system.

It is important that you study the design guide for a more in depth understanding of proper system design.

By following the design guide and these tips you can eliminate many unnecessary headaches that occur when the basic rules of zoning are not followed. Always contact WattMaster Controls if you have any questions.

• Always group zones with similar load profiles on the same HVAC unit.

• Never mix perimeter zones with interior zones on the same HVAC unit.

• Each zoned HVAC unit should have a minimum of 3 to 4 zones. Any less and you should consult the factory.

• If you have electric reheat coils mounted on VAV boxes, it is recommended that a fan powered box be used. Consult the factory for further details concerning this application.

• If there is an economizer on the HVAC unit, it is highly recommended, though not required, that the Zone Manager control the economizer.

• Pressure Independent Zones must always use round dampers or VAV boxes, never rectangular - no exceptions!

• Never attempt to use a zone control system on a true VAV application. See “ Zoning Systems Versus True VAV Systems” on page 9 of this guide for detailed information.

• Each zoned HVAC unit can support a maximum of 16 voting zones. Any zones and you should contact the factory.

• When using auxiliary heat for individual zones, perimeter heat such as baseboard is always preferred and more economical to operate than a fan terminal unit with reheat.

• Bypass dampers should always be sized for 60%-70% of the HVAC units rated CFM.

• Even though the Auto-Zone system has certain features to help protect your equipment, safety devices associated with the HVAC unit.

never override or disconnect any

10 Auto-Zone Systems

Design Considerations

Zoning Design Guide

Load Diversity

A zoning system is designed to improve tenant comfort by dynamically rebalancing the air distribution when used with a typical constant volume rooftop heating/ cooling unit. If zones with extremely different load conditions are serviced by a single rooftop unit, the result will be poor control and excessive wear due to cycling of the equipment.

It is especially important to avoid mixing interior zones (which require cooling all year) with exterior zones (which may require constant heat during winter months). If you must mix zones under these conditions, consider using either VAV boxes with heat or separate external heat on perimeter zones. Auto-Zone Zoning systems offer a variety of methods to control additional zone heat to help you avoid problems.

Group similar loads on an individual unit and use more than one zoned unit if required. Any special loads can be handled by using separate constant volume units.

The Auto-Zone Plus system offers the designer considerable flexibility by allowing both multiple-zoned units and single-zone units to be connected within a single simple system.

Cooling - Partial Load Conditions

The engineer must be aware of several potential problems when applying a zoning system for cold weather operation.

on utilities and provide comfort under conditions when it is not possible to operate the mechanical cooling system.

2.) Low Supply Air Temperatures. Under lightly loaded conditions much of the supply air may be bypassed back into the return air side of the HVAC unit. This bypassing will result in the lowering of the supply air temperature, which may result in the supply air temperature reaching the low temperature safety limit. If the supply air low temperature safety limit is exceeded, the control system will “cut off” the mechanical cooling to protect it from damage. Excessive cycling of the mechanical system will result if this condition persists. Comfort may also suffer if the system cannot run long enough to satisfy cooling demands.

A number of things can be done to reduce this problem. Some of these things depend upon the type of installation.

A void oversizing the unit. Do your all load calculations carefully. Since the zoning system directs the heating or cooling to the zones which require it, you may find that you can use a smaller unit in many cases. Oversizing is the number one cause of excessive low supply air temperature cycling.

Use an economizer. Although this is not a cure-all, it greatly improves operation during cool weather when cooling loads are minimal. Using an economizer also improves ventilation and lowers operating costs.

1.) Low Ambient T emperature Lockout. During very cold weather it is common for mechanical systems to have “low temperature lockouts” which protect equipment from damage if operated under these conditions. Auto-Zone also provides user programmed lockouts for protection purposes, although mechanical safeties should always be used as the final stage of protection.

If the rooftop unit services interior zones with thermal loads, which require cooling when outside temperatures are below the safe operating limits for your equipment, you should seriously consider installing an economizer on your rooftop unit. The Auto-Zone control system is designed to take advantage of an economizer if it is installed. The use of an economizer will save money

Increase cooling minimum airflow. Increase your cooling minimum airflow or damper position settings to allow more air during cooling operation. Be careful to avoid minimum settings that are so high they may cause over cooling of the spaces.

Bypass the air into the ceiling plenum. If you have a system without ducted return, bypass the air into the ceiling plenum instead of into the return air intake. Be careful if you use this method since you may get “dumping” of cold air from your return air grilles. This method works best with plenum returns. Do not use this method

with ducted returns.

Auto-Zone Systems 11

Zoning Design Guide

Design Considerations

Increase your static pressure setpoint. This will help reduce the amount of air being bypassed. Be aware of increased noise levels and the cost of operation if you use excessive static pressures. This will not work if you are using pressure independent zone controllers, since they will maintain a constant flow of air to the zones regardless of duct static pressure. This technique will likely cause over cooling of the spaces due to increased

airflow at minimum positions.

Warning:

If the fan system has the capability of producing static pressures which could damage ductwork you must provide a manual reset, high pressure limit switch (Dwyer 1900-5-MR or equal) to cut off the fan system in the event of high duct static. Do not use your Auto-Zone Zoning system as a safety device!

Heating - Partial Load Conditions

Heating difficulties are less common than cooling difficulties. They are similar in nature, however, and the cures are generally the same. Again, a number of things can be done to reduce the effects of this problem.

Increase heating minimum airflow. Increase your heating minimum airflow or damper position settings to allow more air during heating operation. Be careful to avoid minimum settings that are so high they may cause over heating of the spaces.

method works best with plenum returns. Do not use

this method with ducted returns

Use auxiliary heat . Use an auxiliary heat source in either your VAV boxes or use baseboard heaters.

Auto-Zone has a number of auxiliary heat control options which provide solutions to most problems. Refer to the Auxiliary Heat Control Options topic near the end of this section.

Override Conditions

After-hours overrides can produce aggravated partial load conditions in both the heating and cooling modes. A single zone being overridden for after-hours use most commonly causes the problem. This causes the rooftop equipment to operate for only one zone. The Auto-Zone system offers an improved solution to this common problem by allowing a single override to trigger a group of zones via a “global” override. This allows the system to operate with sufficient load to reduce cycling caused by light load conditions.

Building Pressurization

If you are using an economizer, building pressurization must be addressed. Failure to properly handle building pressurization may result in doors remaining open when the economizer is operating. Pressurization problems can render economizer operation useless. The following suggestions will help to avoid potential problems.

Increase the static pressure. Set the static pressure setpoint to be as high as practical. Increasing static pressure does not help if you are using pressure independent control operation.

Bypass the air into the ceiling plenum. If you have a system without ducted return, bypass the air into the ceiling plenum instead of into the return air intake. This

Use powered exhaust. A power exhaust fan(s) must be used when the system utilizes ducted returns. The return duct pressure drop will cause most barometric relief dampers to function poorly or not at all. Auto-Zone has the ability to control a powered exhaust whenever the economizer is operating.

Use a separate building pressure control. Use a control that operates a relief fan or dampers to relieve building pressure

12 Auto-Zone Systems

Zoning Design Procedures

Zoning Design Guide

General

There are six basic steps to designing an Auto-Zone Zoning system:

1.) Determining the number and location of zones

2.) Sizing the central unit

3.) Duct Considerations

4.) Room air motion and diffuser selection

5.) Bypass damper sizing

6.) Sizing the zone dampers

Step #1 - Determining The Number And Location Of Zones

A single air handler unit can have no more than sixteen zones and no fewer than 3 zones. If the number of zones exceeds sixteen then more than one Zone Manager will be required.

on the wall, ceiling and floor material and location within the building (e.g. top or middle floor), a typical floor of a building usually has several distinct temperature or control zones that are affected uniquely by the outdoor load. These zones are depicted in Figure 1-2. Depending on the size of the building and partition layout, some of these zones may overlap or be insignificant from a zoning standpoint. For example, Zone 11 could be multiple conference or computer rooms where additional zoning would be required, or it could be as small as a corridor where no zoning is required. Similarly, zones 7 and 8 could have no external windows and no partitions between them and could be considered a single zone. Some zones could be divided into multiple offices with full partitions between them, thus requiring separate Zone Controllers because of different internal loads, but the same external load.

Generally, the greater the number of individual Zone Controllers, the greater the comfort. The designer will have to look at the specific building, balancing the costs of multiple zones with the added comfort possible with multiple zones, to match the owner’s requirements.

The primary precaution to be taken in applying the AutoZone Zoning System is to select the zoning so that no zone will be at maximum (design) heating (or cooling) load when any other zone requires the opposite temperature air to satisfy its load. For example, depending

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Figure 1-2: Zones Affected by the Outdoor Load

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It is important to recognize that there are purely internal zones, such as Zone 11 in Figure 1-2, which may contain separate offices/conference/computer rooms. These internal zones could easily have high cooling requirements while external zones (1,2,3, etc.) could be at or near design heating load. This is a misapplication

of the Auto-Zone, zoning (or any heating/cooling change-over) system. The interior zones with cooling

only loads should be served by a separate single zone rooftop HVAC unit (that could be zoned between multiple rooms with a similar load profile). Supplemental heat could be added to the perimeter zones and controlled with the auxiliary heat control board from the Zone Controller. System performance will generally be compromised and frequent change-over from the heating to the cooling mode will occur during the heating season if purely internal zones are combined on the same air-conditioning unit serving perimeter zones. The exposure to the sun has a large affect on the loading of the building. With the building zoned as shown below, for the best control, zones 6, 7, 8, 9 and 10 should be put on one HVAC unit, and zones 1, 2, 3, 4 and 5 on another HV AC unit. Zone 1 1 should be on a separate single zone constant volume HVAC unit.

Auto-Zone Systems 13

Zoning Design Guide

Zoning Design Procedures

Here is another example of the building’s exposure affecting the zoning. Figure 1-3 below

shows a building layout with 7 zones, it has 3 zones with an eastern exposure, 4 zones with a western exposure and two each north and south exposures. This building can be controlled from a single, constant volume air handler. All of the zones have exterior surfaces and there are no totally internal zones, so they will have similar load requirements.

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Figure 1-4: Zones With North And South Exposures.

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Figure 1-3: Zone Layout With External Zones Only.

Figure 1-4 shows a building with 7 zones, 4 of the zones

have a north exposure and the other 3 have a south exposure. Since there is a big difference in the affect on the building between north and south exposures, this situation should use two zoned HVAC units.

Figure 1-5 shows a combination manufacturing facility and office area. The space temperature in the individual zones numbered 1 through 7, would all be controlled by a single HVAC unit. A single constant volume HVAC unit would be used for each of the zones 8 through 12.

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Figure 1-5: Zoning And Constant Volume Units

14 Auto-Zone Systems

Zoning Design Guide

Step #2 - Sizing the Central Unit

Because the zones are controlled with variable air volume, it is unlikely that all zones will be at design load at the same time. The zoning allows for the diversity of loads to be taken into account and will often provide better comfort with a smaller HVAC unit.

In sizing the system, the individual zone loads should be calculated using any dependable load estimating program. Because of diversity, the central unit should be selected for the instantaneous peak load, not the sum of the peak loads, as would be done with a constant volume single zone system. Consider the following when sizing the central unit.

• Size the peak cooling load based on the

month day hour of the greatest total building system load

• Heating should be sized for the lowest design

temperature with an additional margin for morning “pickup”. This margin is generally recommended to be 20 to 25 percent of base design.

Step #3 - Duct Design Considerations

The Auto-Zone system uses a typical low pressure duct design. T o reduce noise problems duct pressures should not exceed 1 inch W.C.

Primary trunk ducts should not be “undersized.” This is especially true for “pressure dependent” systems. Pressure dependent refers to the typical Auto-Zone, Zone Controller without the airflow sensor. W ith larger trunk ducts, it is easier to assure relatively constant pressure to each zone. Runs should be as short as possible, and the trunk duct system kept as symmetrical as possible to facilitate system balancing. Wherever possible, run the trunk ducts above corridors and locate the zone dampers above corridors to reduce the noise in the space and facilitate service of the units. Trunk ducts should be sized for no more than 0.1 inch W.C. drop per 100 feet., and a maximum duct velocity of 2000 FPM.

Note For pressure independent terminal units

with velocity sensors and conventional “VAV” boxes properly selected for “quiet” operation, this 2000 FPM rule can be exceeded by up to 50 percent. The designer, however, should be very experienced in VAV system design before considering modification of this general rule.

T ypical VAV systems with pressure independent terminals use the static regain method for sizing ducts. The typical Auto-Zone Zoning system is a low-pressure, pressure dependent system that utilizes conventional unitary air-conditioning units. These systems should use the equal-friction method of sizing the ducts, and use the maximum loss of 0.1 inch per 100 feet as described above.

Step #4 - Air Motion/Diffuser Selection

Air motion is a consideration for occupant comfort. The selection of diffusers for an Auto-Zone Zoning system requires more care than a constant volume system due to varying flow of air into the zones. Slot diffusers are recommended due to their superior performance at low airflows. Because the zone airflow is variable volume, lower cost round or rectangular diffusers that were satisfactory for constant volume may prove unsatisfactory with an Auto-Zone Zoning system. These diffusers may result in “dumping” of the cold air at low flows in the cooling mode, and insufficient room air motion at low air flows in the heating mode. Although high air motion in the heating mode can be undesirable, a slot diffuser with a high induction ratio generally helps to reduce room air “stratification” when the heating comes from a ceiling diffuser . Linear slot diffusers should be properly selected for the airflow and “throw” suited to the specific installation or zone.

Additional factors to consider in diffuser selection is sound level and throw at design flow. Generally, multiple diffusers will result in lower sound levels in the space, but this must be balanced with the additional hardware and installation costs. It is commonly recom-

Auto-Zone Systems 15

Zoning Design Guide

Zoning Design Procedures

mended that slot diffusers be located near the perimeter or outside wall with the airflow directed into the room. Consult your diffuser supplier or catalog for proper diffuser sizing and location.

Series fan boxes may be used instead of zone dampers where higher induction rates are desirable. If the heat loss on perimeter walls is high, such as large areas of glass, the use of Series Fan Boxes may be indicated to maintain higher induction rates to offset “downdrafts.” If the heat loss is greater than 275 BTUH/LINEAR FOOT, you should use high quality slot diffusers next to the outer wall with the airflow directed inward to counteract downdrafts during heating. Serious downdraft problems occur when heat losses exceed 400 BTUH/linear foot and both high induction diffusers and series fan boxes are recommended.

Step #5 - Bypass Damper Sizing

The function of the bypass damper is to allow a constant volume air handling unit to be used with variable volume zone dampers. The bypass damper modulates on a signal from a duct static pressure sensor to “bypass” air from the supply duct back into the return air duct. If the duct static pressure exceeds the adjustable

setpoint, then the damper opens to bypass more air, and if the static pressure drops below the setpoint, it closes to bypass less air. Using a load calculation program, the bypass damper should be sized to give you the maximum CFM of air to be bypassed, typically 60 to 70 percent of the HVAC units rated capacity.

T o size the damper, select a damper from the table based on calculated bypass CFM and a maximum velocity between 1750-2250 FPM. When determining the bypass duct size, be sure to take into account any transition fittings and associated pressure drops. (See Tables 1-1 & 1-2: Damper Sizing Charts)

Whenever possible, use a single bypass damper and round duct for the bypass. If space limitations or total airflow requires it, multiple bypass dampers can be controlled in parallel or a rectangular damper may be used. For proper control of the Bypass Damper, the static pressure sensor location is very important. Refer to Fig- ures 1-8 Thru 1-10 for proper sensor installation location information and guidelines.

Figure 1-6: Round Bypass Damper

Figure 1-7: Rectangular Bypass Damper & Kit

16 Auto-Zone Systems

Fan

RA Sensor

SA Sensor

Return Air Duct

Supply Air Duct

SP Pickup

Bypass Damper

SP Sensor

Fan

Zoning Design Guide

SA Sensor

Bypass Damper

SP Pickup

Supply Air Duct

RA Sensor

Return Air Duct

SP Sensor

3D Min.2DMin.

Figure 1-8: Preferred Sensor Location

If the trunk ducts are properly sized for minimum pressure drop, the location of the static pickup probe is not particularly critical. It should ideally be located at right angles to the airflow in a straight section of the supply duct approximately 2/3 the distance of the total length of the supply duct. Also the probe should be located not less than 3 duct diameters downstream and 2 duct diameters upstream of any elbow or takeoff. See Fig-

ure 1-8.

Fan

RA Sensor

Return Air Duct

Supply Air Duct

Tubing To Be Equal Length And Size

SP Pickups

Bypass Damper

SA Sensor

SP Sensor

Figure 1-10: Least Desirable Sensor Location If the supply duct comes directly from the unit and im-

mediately splits in opposite directions, the pressure pickup should be located ahead of the split, or as close to it as possible, even if the bypass damper(s) are located downstream of the split.

Step #6 - Sizing the Zone Damper

Use a load program to determine the peak load for each zone. These calculations will be used in selecting the appropriate zone damper sizes.

Using the maximum acceptable velocity for a branch duct (typically 1000-1500 FPM for minimal noise), find the smallest damper that will deliver the required CFM as determined by the load program.

Locate the branch velocity used in the duct design program on the left hand column of the damper sizing chart (T able 1-1). Move across the chart and find the damper which will provide the acceptable CFM to meet your specific zone requirements.

Note Compare the damper size selected against

Figure 1-9: Acceptable Sensor Location

Since the “ideal” location is often difficult to find in an installation, a location in the main trunk where the tip is not in a “negative pressure area” (e.g. just downstream of the inside curve of an elbow) or an area where the tube opening is directly impacted by the velocity of the supply air. See Figure 1-9.

One additional damper may be slaved together for large zones. See zone wiring diagram for details. This should be reserved for situations when it is not practical to use a single large damper . Round zone dampers can be specified to be either pressure dependent or independent.

the duct size to determine if the next size up or down will provide acceptable performance without requiring a transition fitting.

Auto-Zone Systems 17

Zoning Design Guide

Zoning Design Procedures

Pressure Dependent Dampers

With pressure dependent (PD) dampers, the minimum and maximum airflow is set based on damper position. During the final commissioning of the system, each zone is typically balanced with a flow hood and the min/max position is fixed either mechanically or the preferred method, in the controller software. Since this min/max setting is based only on position, as the static pressure fluctuates it will cause the actual airflow at the zone damper to increase or decrease. Therefore the name, pressure dependent since the airflow is dependent on the static pressure. Pressure dependent dampers are available in round or rectangular configurations. See Figure 1-1 1 for a diagram of a typical pressure dependent zone damper.

dent operation. Pressure independent operation is available for round zone dampers only. Pressure independent rectangular dampers are not available. See Figure 1-12 for a diagram of a typical pressure independent zone damper.

When pressure independent dampers are used they must be field calibrated so the CFM of airflow for the minimum and maximum airflow setpoints will be correct. This should be done by the field technician during the commissioning portion of the system installation. The K-factor is the amount of airflow in CFM that the specific damper will produce with 1” W .C. duct static pressure on the damper flow sensor. This K-factor is used by the controller software to maintain the correct minimum or maximum airflow setpoint regardless of the static pressure at the flow sensor. The K-factor and the minimum and maximum damper CFMs can be entered at the Zone Manager on Basic systems, or using the System Manager on Auto-Zone Plus systems. K-factors can also be entered using a personal computer with the ZoneView computer front end software installed. The K-factors for each damper size are listed in Table 1-1: Round Air Damper Selection. Once the correct Kfactors and minimum and maximum damper CFM setpoints are entered, the damper will modulate to try to maintain these CFM airflows during damper operation. If zone dampers or fan terminal units manufactured by others are used, the correct K-factors must be obtained from the equipment manufacturer.

Figure 1-11: Pressure Dependent Damper

Pressure Independent Dampers

When using pressure independent (PI) dampers this minimum and maximum is set based on actual CFM of airflow through the damper. Airflow is measured using a pickup tube mounted in the zone damper and an electronic air flow sensor. Using this method you always know the actual airflow through each zone damper instead of just the damper percentage open. The minimum and maximum settings are based on this actual airflow reading. As the static pressure fluctuates, the flow sensor reads the variation and automatically repositions the damper to maintain the minimum or maximum flow setpoints. Since the minimum or maximum airflow is maintained independently of the static pressure available in the duct it is called pressure indepen-

Figure 1-12: Pressure Independent Damper

18 Auto-Zone Systems

Zoning Design Guide

Round Damper Blade Assembly

1/2" Foil Faced Insulation

AIRF

FLOW

LO IR A

Bypass & Slave Dampers Zone Dampers

Damper Round Duct Size

CFM @ 1” Velocity Pressure

Air Flow Probe “K” Factor- For Pressure

Independent Applications Only

(Area Ft

)

Round Damper Blade Assembly

Zone Controller

1/2" Foil Faced Insulation

Actuator

Control Enclosure (Cover Removed)

Bypass & Slave Interface

Table 1-1: Round Damper Selection Data

6”

(0.188)

474 950 1417 2120 2908 3700

8”

(0.338)

10”

(0.532)

F IR A

12”

(0.769)

I R F

Actuator

Control Enclosure (Cover Removed)

14”

(1.050)

16”

(1.375)

Velocity Through Zone Damper

FPM

750 - Zone

141

(0.03)

1000 - Zone

188

(0.05)

1250 - Zone

235

(0.07)

1500 - Zone

282

(0.09)

1750 – Bypass Only

329

(0.12)

2000 – Bypass Only

376

(0.15)

2250 – Bypass Only

423

(0.18)

WattMaster reserves the right to change specifications without notice

Rectangular Dampers

Auto-Zone rectangular dampers are high quality aluminum construction with opposed/air foil designed blades for superior control and have both blade and jamb seals for tight shut off. The dampers are installed using a mounting flange. The purpose for the flange mounting is to allow as much unrestricted free space within the duct as possible.

Many companies utilize slide-in type dampers which

Airflow Through Zone Damper - CFM

inches W.C . With Air Damper Full Open)

(∆P

254

(0.02)

338

(0.03)

423

(0.04)

507

(0.06)

592

(0.08)

676

(0.10)

761

(0.13)

399

(0.01)

532

(0.02)

665

(0.03)

798

(0.04)

931

(0.06)

1064

(0.07)

1197

(0.09)

577

(0.02)

769

(0.03)

961

(0.04)

1154

(0.05)

1346

(0.06)

1538

(0.07)

1730

(0.09)

788

(0.01)

1050

(0.02)

1313

(0.03)

1575

0.04) 1838

(0.05)

2100

(0.07)

2363

(0.08)

1031

(0.01)

1375

(0.01)

1718

(0.02)

2062

(0.03)

2405

(0.04)

2749

(0.05)

3094

(0.06)

can cause air flow problems. These slide-in dampers require that the damper frame be inside the duct. Imagine an 8 x 10 rectangular duct using a slide in damper with a frame thickness of 1”. The frame alone would reduce the opening to 6 x 8.

Another possible problem encountered with rectangular dampers is the blade width. Many damper manufacturers supply dampers with 6” or 8” dampers blades. This can become a major problem, for example, if the

Auto-Zone Systems 19

Zoning Design Guide

Zoning Design Procedures

damper has a height of 10”. In this case the damper would utilize an 8” blade and a 2” blade stop or dam would be installed across the base of the damper. Taking into consideration the “blade stop” and the frame, a 10 x 10 damper would have a reduced opening of 6 x 8 inside the duct. Many contractors have experienced low air flow problems on projects only to discover this hidden problem of the dampers actually creating the restriction. Auto-Zone utilizes a variety of blade widths in order to accommodate the size of the damper instead of the damper trying to accommodate the size of the blade.

Table 1-2: Rectangular Damper Selection Data

Rectangular Dampers

Damper

Height

“B”

Damper

Width

“A”

8” 410

10” 510

12” 560

14” 660

16” 750

18” 770

20” 850

22” 930

24” 950

26” 990

28” 1070

30” 1020

32” 1090

34” 1150

36” 1060

8” 10” 12” 14” 16” 18” 20” 22” 24” 26” 28” 30” 32” 34” 36”

Airflow Data with Full Open Damper – CFM @ 1000 FPM Velocity

For airflow CFM at other velocities use these multipliers: 750 FPM = 0.75, 1250 FPM = 1.25, 1500 FPM = 1.5, 2000 = 2.0, 2250 = 2.25

530

640

740

850

(0.16)

(0.10)

(0.07)

(0.05)

(0.04)

590

690

800

910

(0.10)

(0.07)

(0.05)

(0.03)

650

730

850

970

(0.07)

(0.05)

(0.03)

(0.02)

770

880

1030

1180

(0.05)

(0.03)

(0.02)

(0.01)

890

1030

1200

1370

(0.04)

(0.03)

(0.02)

(0.01)

980

1180

1380

1580

(0.03)

(0.01)

1090

1330

1550

1770

(0.03)

(0.02)

(0.01)

1210

1480

1730

1980

(0.02)

(0.01)

1290

1630

1900

2170

(0.02)

(0.01)

(0.02)

(0.01)

1390

(0.01)

1500

(0.01)

1550

(0.01)

1660

(0.01)

1770

(0.01)

1790

(0.01)

1780

2080

(0.01)

1930

2250

(0.01)

2080

2430

(0.01)

2230

2600

(-)

2380

2780

(-)

2520

2670

(-)

WattMaster reserves the right to change specifications without notice

(-)

2380

(-)

2570

(-)

2780

(-)

2970

(-)

3180

(-)

3090

(-)

(∆PS - inches W.C. @ 1000 FPM Velocity)

970

(0.03)

1030

(0.02)

1090

(0.01)

1330

(0.01)

1540

(0.01)

1780

(0.01)

1990

(0.01)

2230

2440

2680

2890

3130

3340

3580

3510

1080

(0.03)

1150

(0.02)

1210

(0.01)

1480

(0.01)

1710

(0.01)

1980

(0.01)

2210

2480

(-)

2710

(-)

2980

(-)

3210

(-)

3480

(-)

3710

(-)

3980

(-)

3930

(-)

1190

(0.02)

1260

(0.01)

1330

(0.01)

1630

(0.01)

1880

(0.01)

2180

2430

(-)

2730

(-)

2980

(-)

3280

(-)

3530

(-)

3830

(-)

4080

(-)

4370

(-)

4350

(-)

1300

(0.02)

1380

(0.01)

1460

(0.01)

1760

(0.01)

2060

(-)

2350

(-)

2650

(-)

2950

(-)

3250

(-)

3550

(-)

3850

(-)

4150

(-)

4450

(-)

4750

(-)

5040

(-)

1410

(0.02)

1500

(0.01)

1580

(0.01)

1910

(0.01)

2230

2550

2870

3200

3520

3850

4170

4500

4820

1520

(0.01)

1610

(0.01)

1700

(0.01)

2060

2400

(-)

2750

(-)

3090

(-)

3450

(-)

3790

(-)

4150

(-)

4500

(-)

4850

(-)

NA NA NA NA NA NA

1630

(0.02)

1730

(0.01)

1820

(0.01)

2210

(-)

2570

(-)

2950

(-)

3310

(-)

3700

(-)

4060

(-)

4450

(-)

4820

(-)

NA NA NA NA NA

1740

(0.01)

1840

(0.01)

1940

2360

(-)

2740

(-)

3150

(-)

3530

(-)

3950

(-)

4330

(-)

4750

(-)

NA NA NA NA

1850

(0.01)

2000

(0.01)

2060

(-)

NA NA NA

(-)

2510

(-)

2910

(-)

3350

(-)

3750

(-)

4200

(-)

4600

(-)

NA NA

1970

(0.01)

2080

(0.01)

2190

(-)

2640

(-)

3090

(-)

3540

(-)

3990

(-)

4440

(-)

4880

(-)

20 Auto-Zone Systems

Zoning Design Guide

Auxiliary Heat Control Options

The Auto-Zone Zoning system offers the user a variety of methods to deal with zone heating requirements. In order to control zone heat, an optional Relay Expansion Board is required. When deciding how to handle zone heating requirements the user should consider the following:

• Does the rooftop unit have heat?

• Are you using fan-powered boxes with reheat?

• Is auxiliary heat such as baseboard or radiant

ceiling panels used?

If the zone has some type of heat, the user must consider how the heat is to be used. Typical questions that should be asked:

Q: Should the zone heat be used as a first stage where

it will become active before a heating demand is created at the rooftop unit?

A: This mode is useful if you expect to have both

heating and cooling demands at the same time. The zone will use it’s own heat and allow the rooftop unit to continue to provide cooling for other zones. This mode is also useful if the roof top unit does not have any heating capabilities.

Q: Is the zone heat only to be used as a second stage,

where it will be activated only if the roof top unit cannot maintain the space temperature, such as during very cold weather?

A: In this mode of operation the rooftop will examine

the heating and cooling demands and try to satisfy all of the zones by switching between heating and cooling as required. The zone heat will only be activated if the zone temperature falls below a selected limit.

Relay Expansion Board Outputs

The following describes the operation of each of the relays on the optional relay expansion board. The user can choose the appropriate relays for any given application.

Relay #1 - Parallel Fan

If the Zone is in cooling or vent mode, the parallel fan can activate anytime the zone temperature drops 0.5° F below the heating setpoint. It deactivates when the temperature rises above the heating setpoint.

Relay #2 - Box Heat

If the zone is in cooling or vent mode then the box heat can activate anytime the zone temperature drops 1.5° F below the heating setpoint. It deactivates when the temperature rises to within 1.0° F of the heating setpoint. Box heat is not allowed to activate in the heating mode when there is hot air being supplied by the air handling unit. This output was intended to allow zone reheat while the Zone Manager is satisfying cooling demands in other zones.

Relay #3 - Aux. Heat

In the occupied mode, the aux heat can activate anytime the zone temperature is 0.5° F below the aux heat setpoint. It deactivates when the temperature rises 0.5° F above the aux heat setpoint. In the unoccupied mode, the aux heat uses the unoccupied heating setpoint with the same deadband values mentioned above. This prevents the zone from maintaining the same aux heat setpoint at night that it does during the daytime. The Parallel Fan and Box Heat are prevented from coming on until the aux heat is energized.

This output was intended to allow zone heating to augment the normal heating mode and also to allow a zone an attempt to satisfy its own heating needs before creating a heating demand at the Zone Manager.

Q: Should the zone heat be locked out if the rooftop

unit is supplying warm air?

A: Many times it is desirable to use the rooftop

heating whenever possible and only use zone heat when the rooftop unit is in cooling. This mode of operation will lockout zone heat if the rooftop is delivering heated air.

Relay #4 - Series Fan

The series fan runs anytime the main fan is running. This includes occupied and unoccupied modes. The fan can only start running when the zone damper is closed, so it determines that the damper is closed before starting the fan.

Auto-Zone Systems 21

Zoning Design Guide

System Installation

Mounting Of Controllers

All Auto-Zone Round Dampers or Rectangular Damper Kits have the required controllers, actuators etc. factory mounted in an indoor rated control enclosure. If you wish to use another manufacturers dampers for zoning control you must purchase Zone or Bypass Packages from WattMaster. These are furnished without a mounting enclosure. Most local codes require these components be mounted in an enclosure. If yours does not require this it is still strongly recommended that you do mount them in an enclosure. Components that are not in an enclosure are in danger of being damaged, and are susceptible to dirt and moisture contamination. You may furnish your own enclosure or one is available from WattMaster. The part number for the WattMaster enclosure is EE000075-01. This is an indoor rated enclosure. If the zone mounting location is susceptible to water damage, watertight enclosures can be purchased at any local electrical supply. Mounting location for the controllers should not violate any local, state or national codes.

device. Possible problems you may encounter using common transformers to power multiple devices are:

• If polarity is not maintained between devices,

shorting of the transformer will occur resulting in damage to the electronics.

• When using one transformer to power multiple

devices it is possible to lose most or all of your system if the transformer fails.

• It is important when powering multiple devices

from one transformer that total VA load and wiring voltage drops be taken into account for proper sizing of the transformer and wire. (See Table 3 on page 23)

It is therefore recommended that in most installations individual transformers be installed for each device. This will greatly reduce the possibility of errors and possible damage to the system.

System Wiring

Wiring requirements for Auto-Zone systems can be broken down into four main categories:

1.) Power Wiring

2.) Communications Wiring

3.) Controller Wiring

4.) Sensor Wiring

Each category should be thoroughly understood and implemented in order to have a trouble free installation.

Power Wiring

All Auto-Zone devices are powered by 24 VAC. It is possible to power the system using one or more common transformers or individual transformers for each

Power wiring should always be done in accordance with any local, state, or national codes.

It is also important to note that THE HVAC UNITS

FACTORY TRANSFORMER SHOULD NEVER BE USED TO POWER Auto-Zone devices! Normally

transformers on typical HVAC units are sized to only handle the load of the units factory installed controls. A separate transformer must be used.

Communication Loops

The Auto-Zone system utilizes two different communications loops. The Basic system uses a 9600 Baud RS-485 communications loop (Local Loop) only. The Plus system uses two different communications loops. It has a 9600 Baud RS-485 communications loop (Local Loop) like the Basic system but also has an RS-485 19200 baud communication loop (Network Loop) that connects the Zone Managers together and connects the CommLink II communications interface.

22 Auto-Zone Systems

Zoning Design Guide

W attMaster requires that all communication wire be 18 gauge minimum, two wire shielded cable, Belden #82760 or equivalent. W attMaster offers AZWR series communications cable for this purpose. The 18 gauge color coded and labeled wire is available for the local loop and the network loop communications wiring. The local loop wire is supplied in 1000 ft. spools and is labeled “Local Loop” with a green candy stripe. The network loop wire is supplied in 500 ft. spools and is labeled “Network Loop” with a red candy stripe.

Local Loop Wire

Figure 1-13: WattMaster Communications Wire

The loop is best connected in a daisy chain configuration, meaning the loop is connected from one controller to another. It is not necessary to sequentially address the zone controllers in relation to their location on the loop.

Even though the daisy chain configuration is preferred, the star configuration can also be used. If required, a combination of the two can also be used. Remember, the best communications loop wiring is the one which utilizes the minimum number of ends while using the shortest wiring path.

Communication Wiring terminals on most Auto-Zone controllers are marked “T”, “R” and “SHLD” (Note: instead of SHLD the CommLink is marked “G” and the Basic Zone Manager is marked “SH”). All wiring should be connected T to T , R to R and SHLD to SHLD throughout the entire loop system. Communication wire

Network Loop Wire

should be color coded to facilitate error free wiring. The communication loops will not work if any of the wires are reversed or otherwise landed incorrectly . Communications loops can be run up to a maximum of approximately 4000 ft. in total length. If your system exceeds this length, please consult the WattMaster factory for more information regarding extended communication loop lengths and solutions.

Caution: Unless the communications loop

is installed in conduit, be careful to position the cable away from high noise devices like fluorescent lights, transformers, VFD’s, etc. Conduit is not required for communications loop wiring unless required by local codes.

Tip: Incorrect wiring of the communications

loop is the most common mistake made during installation. Before beginning installation, write down the wire color used on each terminal connection and consistently maintain that color code. It is recommended that a continuous wire run be made between devices. Anytime a splice is made in the cable you increase your chance of problems. If a splice must be made, should be soldered and wrapped or if soldering is not possible use butt splice crimp connectors and wrap tightly with electrical tape.

Caution: Make sure when you are inserting

Never use wire nuts! Cable

wires into the terminal blocks that strands of wire do not stick out and touch the adjacent terminals. If adjacent wires touch each other or another terminal, shorting and subsequent damage to the circuit board could result

Auto-Zone Systems 23

Zoning Design Guide

COMM

LINK

COMM

LINK

System Installation

Computer

(Optional)

O M

M LINK

L O

O D

E M

WCLI

T M

A S

T E R

N T R

S,N C

CommLink II

(Optional)

y c

h r

n o

u s

t a

L i n

SIG

DET

RDY

SND

REC

PWR

NTROLS

Remote Link

(Optional)

RS485 Loop

24VAC

RS485 Loop

HVAC Unit

Zone Manager

UTO-ZONE

AUTOZONE

WEDJANUARY11 2001

OCCUPIED

Zone Controllers Occupy Addresses 1 through 16.

Zone

Controller #1

RAM

32K

FLOW

CX4

CX3

CX8

U 8

RN1 1

B31920P

74H

S6264L-70P

4.00F AZ

9936

573N

094

R 27

CX9

C 66

RAM

EPROM

C 14

80C55

R22

P.U.

R32

R23

T'STA

ILIPS

-5-1

R24

U11

52 5

H P

R25

ADDRE

ADD

CX10

75176

16 32

LD3

TOKEN

NET

R26

R14

V 1

250

562

Y S

101

REC

SCAN

fTimesNew

Roman|b0|i0|

Roman|b0|i0|c0|p18;

c0|p18;OMRON

G5L-114P-PS 24VDC CONTACT:

MDL

VR1

UL/CSA5A250VAC

fTimesNew

7824

7824C

24VAC

fTimesNew

Roman|b0|i0|

9936

Roman|b0|i0|c0|p18;

64A

c0|p18;OMRON

G5L-114P-PS

MC340

24VDC CONTACT:

R16

UL/CSA5A250VAC

R17

GND

R5 R6 R7

P J1

P J2

CX1

U 1

TC U 32K

16L8

R1 R2 R3

CX2

Q 1

7 4H 3 19

20 2 59

PS C 2

S IO N

TO R

E XP A N

AC T U A

Controller #16

5 62 R E V . 2

24VAC 24VAC

Zone

RAM

32K

FLOW

CX4

CX3

CX1

CX8

U 8

RN1

4.00F

32K

9 93

L-7

094

R 27

16L8

CX9

C 66

RAM

EPROM

8 C 1

80C55

R22

CX2

P.U.

R32

R23

4H 3 19

T'STA

ILIPS

-5-1

R24

H P

R25

ADDRE

ADD

CX10

LD3

TOKEN

NET

R26

250

2 1

6 Y S 10

REC

SCAN

fTimesNew

Roman|b0|i0|

Roman|b0|i0|c0|p18;

c0|p18;OMRON

G5L-114P-PS 24VDC CONTACT:

MDL

VR1

UL/CSA5A250VAC

fTimesNew

7824

7824C

24VAC

fTimesNew

Roman|b0|i0|

9936

Roman|b0|i0|c0|p18;

64A

c0|p18;OMRON

G5L-114P-PS

MC340

24VDC CONTACT:

R16

UL/CSA5A250VAC

R17

GND

Figure 1-14: Auto-Zone Basic System Communication Loop Wiring

Zone Controllers Occupy Addresses 1 through 16. CV Controllers And Other Add On Devices, Occupy Addresses 18 trough 30

Computer

(Optional)

RS485 Network Loop

24VAC

HVAC Unit #1

Zone Manager

19200 Baud

9600 Baud

O M

I N K

I I

L O

O D

E M

WCLI

AT T

M A S

T E R

O N

T R O

S,N

CommLink II

SychronousDataLink

SIG

DET

RDY

SND

REC

PWR

CON

ROLS

Remote Link

(Optional)

Network Loop To Other Zone Managers

24VAC

RS485 Local Loop #2

RS485 Local Loop #1

HVAC Unit #2 Zone Manager

The Loop Does Not Have To Follow The Board Address Sequence

Zone

Controller #1

RAM

R34

R18

32K

FLOW

CX4

CX3

CX8

U 8

RN1

74H

4.00F

31920PS

6264L-70P 9936

C 573N

094

R 2 7

CX9

C 6

RAM

EPROM

8 C 14

80C55

R22

P.U.

R32

R23

-1

T'STA

ILIP

R24

2-5

M S

1/3 55

IP IL

H P

R25

ADDRE

ADD

CX10

93C

75176

LD3

TOKEN

NET

100

R26

13 R 14

V 1

250

562

101

REC

SCAN

fTimesNew

Roman|b0|i0|

Roman|b0|i0|c0|p18;

c0|p18;OMRON

G5L-114P-PS 24VDC CONTACT:

MDL

VR1

UL/CSA5A250VAC

fTimesNew

7824

7824C

24VAC

fTimesNew

Roman|b0|i0|

9936

Roman|b0|i0|c0|p18;

64A

c0|p18;OMRON

G5L-114P-PS

MC340

24VDC CONTACT:

R16

UL/CSA5A250VAC

R17

K 2

GND

24VAC

Zone

Controller #1

RAM

32K

FLOW

CX4

CX3

CX8

U 8

RN1

B31920P

74HC

4.00F AZZ

6264L-70PC 9936

573N

094

R 27

CX9

C 66

RAM

EPROM

C14

80C55

R22

P.U.

R32

R23

T'STA

ILIPS

-5-1

R24

C11

H P

R25

ADDRE

ADD

CX10

93C

75176

16 32

LD3

TOKEN

PJ2

NET

100

R26

13 R 14

250

562

S101 R E

REC

SCAN

R12

R11

R10

fTimesNew

Roman|b0|i0|

Roman|b0|i0|c0|p18;

c0|p18;OMRON

G5L-114P-PS 24VDC CONTACT:

MDL

VR1

UL/CSA5A250VAC

fTimesNew

7824

7824C

24VAC

fTimesNew

Roman|b0|i0|

9936

Roman|b0|i0|c0|p18;

64A

c0|p18;OMRON

G5L-114P-PS

MC340

24VDC CONTACT:

R16

UL/CSA5A250VAC

R17

K 2

GND

24VAC

Zone

Controller #16

RAM

32K

FLOW

CX4

CX1

U 1

TC U 32K

16L8

R1 R2 R3

CX2

Q 1

B31920P

74H

259

S C 2

R5 R6 R7

SIO

EX P N A N

TOR

AC TU A

CX3

CX1

CX8

U 8

RN1

4.00F

32K

62 9

L-7

094

R 2 7

16L8

CX9

C 6

RAM

EPROM

80C55

R22

CX2

P.U.

R32

R23

4H 3 19

-1

T'STA

ILIP

R24

2-5

M S

1/3 55

IP IL

H P

R25

ADDRE

ADD

CX10

16 32

LD3

TOKEN

NET

R26

250

REC

SCAN

fTimesNew

10 1

fTimesNew

Roman|b0|i0|

Roman|b0|i0|c0|p18;

c0|p18;OMRON

G5L-114P-PS 24VDC CONTACT:

MDL

VR1

UL/CSA5A250VAC

fTimesNew

7824

7824C

24VAC

fTimesNew

Roman|b0|i0|

9936

Roman|b0|i0|c0|p18;

64A

c0|p18;OMRON

G5L-114P-PS

MC340

24VDC CONTACT:

R16

UL/CSA5A250VAC

R17

K 2

GND

24VAC

Zone

Controller #16

RAM

32K

FLOW

CX4

CX1

U 1

TC U 32K

16L8

R1 R2 R3

CX2

Q 1

74H

31920P

C 259

S C 2

R5 R6 R7

E IO

XPAN N

TOR

A C TU A

CX3

CX1

CX8

U 8

RN1

4.00F

AZZ

32K

64 36

L-70

094

R 27

16L8

CX9

C 66

RAM

EPROM

8 C 1

80C55

R22

CX2

P.U.

R32

R23

T'STA

ILIPS

-5-1

R24

H P

R25

ADDRE

ADD

CX10

SIO

LD3

TOKEN

NET

R26

250

2 1

REC

SCAN

fTimesNew

Roman|b0|i0|

Roman|b0|i0|c0|p18;

c0|p18;OMRON

G5L-114P-PS 24VDC CONTACT:

MDL

VR1

UL/CSA5A250VAC

fTimesNew

7824

7824C

24VAC

fTimesNew

Roman|b0|i0|

9936

Roman|b0|i0|c0|p18;

64A

c0|p18;OMRON

G5L-114P-PS

MC340

24VDC CONTACT:

R16

UL/CSA5A250VAC

R17

K 2

GND

24VAC

Constant Volume

(Addresses Start At 18)

COMM

SHLD

LD4

REC.

E XP A N

A C TU A

12V AIN

AIN

5 GND

GND

AOUT

PRESSURE

SENSOR

To Any Other

CV Controllers

Or Add On Devices

Constant Volume

(Addresses Start At 18)

COMM

SHLD

LD4

REC.

EX P A N

AC T U A

12V AIN

1 AIN

2 AIN

3 AIN

4 AIN

5 GND

GND

AOUT

PRESSURE

SENSOR

To Any Other

CV Controllers

Or Add On Devices

Controller

RAM

EPROM

485 COMM

ADDRESS ADD

0-5 VDC

YS101564

0-1

VDC

Controller

RAM

EPROM

485 COMM

ADDRESS ADD

DOG

0-5 VDC

YS101564

0-1

VDC

32K 8K

COMM

TEST

24VAC

32K 8K

COMM

TEST

24VAC

RELAY

OUTPUT COM 1-3 OUT

1 OUT

2 OUT

3 OUT

OUT

4 OUT

5 COM 4-5

4-5

PWR

GND

24VAC

RELAY

OUTPUT COM 1-3 OUT

1 OUT

2 OUT

3 OUT

OUT

4 OUT

5 COM 4-5

4-5

PWR

GND

24VAC

Figure 1-15: Auto-Zone Plus System Communication Loop Wiring

24 Auto-Zone Systems

Zoning Design Guide

Controller Wiring

All controller wiring should be in accordance with all local, state, and national codes. It is recommended that all wire be a minimum of 18 AWG unless otherwise specified in the charts below. Controller connections and wire sizing is as follows:

Zone Manager

• 24 VAC Supply Voltage (25 VA)

(2) Conductors - Determine minimum wire size from Figure 1-16 on page 26.

• Communications Loop

(2) Conductors 18 gauge minimum twisted pair with shield (WattMaster communication wire, Belden #82760 or equal)

• Supply Air Temperature Sensor

(2) Conductors 24 gauge minimum

• Return Air Temperature Sensor

(2) Conductors 24 gauge minimum

• Outside Air Sensor

(2) Conductors 24 gauge minimum

• Supply Static Pressure Sensor

(2) Conductors 24 gauge minimum

• Bypass Damper

(4) Conductors 24 gauge minimum

• HVAC Unit Control Wiring

(6) Conductors 24 gauge minimum R (Common), G (Fan), Y1 (Cool 1), Y2 (Cool 2), W1 (Heat 1), W2 (Heat 2)

For Auto-Zone Plus System With Optional Staging Expansion Board up to an additional (8) conductors Y3 through Y6, W3 Through W6

System Manager

• 24 VAC Supply Voltage (25 VA)

(2) Conductors - Determine minimum wire size from Figure 1-16 on page 26.

• Communications Loop

(2) Conductors 18 gauge minimum twisted pair with shield (WattMaster communication wire, Belden #82760 or equal)

Zone Controller

• 24 VAC Supply Voltage (10 VA)

(2) Conductors - Determine minimum wire size from Figure 1-16 on page 26.

• Communications Loop

(2) Conductors 18 gauge minimum twisted pair with shield (WattMaster communication wire, Belden #82760 or equal)

• Room Sensor

(2) Conductors 24 gauge minimum

(3) Conductors if using optional slide

Sensor Wiring

Auto-Zone temperature sensors utilize a type III thermistor element that is one of the most commonly used sensors in the building controls industry. Sensor wire should be a minimum of 24 gauge however larger wire such as 18 gauge is commonly used.

Conventional thermostat cable is acceptable in most commercial and institutional installations. In some installations which have the potential for high electrical noise, such as broadcast facilities (radio, TV , etc.), heavy industrial (machinery, welding equipment, etc.), and medical (x-ray, scanning, etc.), it is advisable to use shielded cable on sensors which are located in or close to these environments. The same cable used for the communication bus can be used in these situations.

Sensor requirements are:

• Supply Air Sensor

(2) Conductors 24 gauge minimum

• Return Sensor

(2) Conductors 24 gauge minimum

• Outside Air Sensor

(2) Conductors 24 gauge minimum

• Room Sensor

(2) Conductors 24 gauge minimum

(3) Conductors if using optional slide adjust

Auto-Zone Systems 25

Zoning Design Guide

System Installation

Some installers like to use one large 24VAC transformer to power several controllers. This is allowable as long as polarity is maintained to each controller on the transformer circuit.

recommends using a separate transformer for each controller in order to eliminate the potential for damaging controllers due to incorrect polarity.

Using separate transformers also allows redundancy in case of a transformer failure. Instead of having 8 controllers inoperative because of a malfunctioning transformer you have only 1 controller off line. If the installer does decide to use a large transformer to supply power to several controllers, the following transformer and wire sizing information is presented to help the installer correctly supply 24VAC power to the controllers.

Following is a typical example to help the installer to correctly evaluate transformer and wiring designs.

Each Zone Controller with actuator requires 10 VA @ 24VAC power. In the examples below we have a total of 8 Zone Controllers.

8 Zone Controllers @ 10VA each................ 8 x 10VA = 80VA.

The above calculation determines that our transformer will need to be sized for a minimum of 80VA if we are to use one transformer to power all the controllers.

Next we must determine the maximum length of run allowable for the wire gauge we wish to use in the installation. Each wire gauge below has a voltage drop per foot value we use to calculate total voltage drop.

18ga wire.................................0.00054 = voltage drop per 1’ length of wire

16ga wire.................................0.00034 = voltage drop per 1’ length of wire

14ga wire.................................0.00021 = voltage drop per 1’ length of wire

For our example we will use 18 gauge wire. WattMaster recommends 18 gauge as a minimum wire size for all power wiring.

Next use the voltage drop per foot value for 18 gauge wire from the list above and multiply by the total VA load of the 8 controllers to be installed.

0.00054 (Voltage drop per foot for 18 gauge wire) x 80VA controller load = Volts/Ft.

WattMaster controllers will operate efficiently with a voltage drop no greater than 2 Volts. Divide the total allowable voltage drop of 2 Volts by the number you arrived at above and you have the maximum number of feet you can run the 18 gauge wire with an 80VA transformer with no more than a 2 Volt drop at the farthest controller from the transformer..

Parallel circuiting of the wiring instead of wiring all 8 controllers in series allows for longer wire runs to be used with the same size wire (as shown in our examples below). transformer size, multiple transformers, circuiting, etc., when laying out an installation. No matter what layout scheme is decided upon, it is mandatory that the farthest controller on the circuit is supplied with a minimum of 22 Volts.

It is often necessary for the installer to calculate and weigh the cost and installation advantages and disadvantages of wire size,

Warning:

If polarity is not maintained, severe damage to the controllers may result. WattMaster Controls

2 (Volts total allowable voltage drop)

0.0432 (Voltage drop per 1 ft. @ 80VA load)

0.0432

46.30 feet

24VAC Power - Transformer & Wire Sizing Considerations

ZONE

CONTROLLER

ZONE

CONTROLLER

120 / 24VAC

ZONE

CONTROLLER

ZONE

CONTROLLER

Distance A to B cannot exceed 46.30 Ft.

ZONE

CONTROLLER

ZONE

CONTROLLER

ZONE

CONTROLLER

ZONE

CONTROLLER

ZONE

CONTROLLER

ZONE

CONTROLLER

ZONE

CONTROLLER

ZONE

CONTROLLER

Distance from A to B cannot exceed 92.60 Ft. Distance from A to C cannot exceed 92.60 Ft.

CONTROLLER

ZONE

120 / 24VAC

Component Power Requirements

System Manager ........ ..............25VA GPC Controller.... .....................20VA

Zone Manager..........................25VA

Wetbulb Module .......................20VA

Zone Controller ........................10VA Lighting Panel Controller ..........25VA

CV Controller............................20VA

Zone Relay Expansion Board ...10VA

CV-C Controller................. .......20VA Staging Expansion Board .........20VA

Optimal Start Scheduler ...........25VA

Figure 1-16: Transformer And Wire Sizing Considerations

ZONE

CONTROLLER

ZONE

CONTROLLER

ZONE

CONTROLLER

BCDE

ZONE

CONTROLLER

ZONE

CONTROLLER

ZONE

CONTROLLER

120 / 24VAC

Distance from A to B cannot exceed 185.20 Ft. Distance from A to C cannot exceed 185.20 Ft. Distance from A to D cannot exceed 185.20 Ft. Distance from A to E cannot exceed 185.20 Ft.

JOB NAME

FILENAME

WIRSIZ1.CDR

DATE:

11/30/99

PAGE

DESCRIPTION:

Wire & Transformer Sizing

CONTROLS

DRAWN BY:

Auto-Zone

B. CREWS

ZONE

CONTROLLER

ZONE

CONTROLLER

26 Auto-Zone Systems

Application Notes:

Zoning Design Guide

Zoning 30 And 40 Ton Units

When using large HVAC units for zoning applications, several rules must be considered to prohibit potential problems.

Because of the large air flow capacities of the 30 and 40 ton units, great care must be taken in sizing zone and bypass dampers.

Use these guidelines to help keep you out of trouble.

• Always use the Auto-Zone Plus system even if you only have one unit that you are zoning.

• Generally you should use constant volume units in your zoning system design. If your units are to be equipped with variable frequency drives or inlet vanes, please consult WattMaster Controls for assistance.

• The OE340-10-AGSTG relay expansion card is usually required for each Zone Manager controlling two or more stages of cooling.

• Bypass dampers should be sized for 60 to 70% of the rated CFM of the unit. Because of the large air volumes involved, rectangular dampers should be used instead of round dampers. Consult the rectangular damper sizing guide (Table 1-2 on page 25), for CFM ratings.

• Large units should always have a minimum of 6 zones due to the high air flow capacities.

• To prevent excessive noise in the system, zone damper total minimum airflow settings should be equal to or preferably greater than 30% of the units rated CFM.

As an added precaution, we recommend a high duct static safety switch be installed (Dwyer Model 19005-MR or equal) to prevent over pressurization of the ductwork.

Auto-Zone Systems 27

WattMaster Controls Inc. • 8500 NW River Park Drive • Parkville MO • 64152 Phone (816) 505-1100 E-mail: mail@wattmaster.com Fax (816) 505-1101

Auto-Zone Control Systems Zoning Design User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual