McQuay RDE076C Installation Manual

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Installation and Mainenance Manual IM791-2

Applied Packaged Rooftop System Heating and Cooling with Evaporative Condenser

Gas/Electric Models RPE/RDE 076C-150C 76 to 150 Tons

Group: Applied Systems Part Number: IM791-2

Date: September 2010

Contents

Unit Nameplate............................................................ 3

Gas Burner Nameplate....... .......................................... 3

Hazard Identification Information............................... 3

Nomenclature....... ..................................................... ... 3

Unit Description........................................................... 4

Condenser Fan Arrangement ....................................... 5

Refrigerant Circuit Schematic ..................................... 5

Refrigeration Piping..................................................... 6

Spray System Plumbing with Optional Non-Chemical

Water Treatment .......................................................... 9

Bleed Off and Water Consumption ........................... 10

Control Locations ...................................................... 10

Walk-In Service Compartment.................................. 14

Receiving Inspection.................................................. 17

Unit Clearances.......................................................... 17

Ventilation Clearance ................................................ 18

Overhead clearance.................................................... 18

Roof Curb Assembly and Installation........................ 19

Reassembly of Split Units.......................................... 24

Condensate Drain Connection ................................... 26

Unit Piping................................................................. 26

Steam Coil Piping...................................................... 28

Steam Piping Recommendations ............................... 28

Steam Trap Recommendations.................................. 28

Damper Assemblies................................................... 30

Cabinet Weatherproofing........................................... 31

Installing Ductwork ................................................... 32

Installing Duct Static Pressure Sensor Taps.............. 33

Electrical Installation ........................................................ 34

Field Power Wiring.................................................... 34

Field Control Wiring.................................................. 37

Relief Damper Tie-Down .......................................... 38

Spring Isolated Fans....................................... ............ 38

Adjusting Spring Mounts........................................... 38

Spring Isolated Compressors..................................... 40

Power-up.................................................................... 41

Fan Operation ............................................................ 41

Economizer Operation............................................... 41

Heating....................................................................... 46

Legend ....................................................................... 47

Typical Control Schematic: Discharge Air Control

(DAC) ........................................................................ 50

Typical Control Schematic: Zone or Space Comfort Con-

trol (SCC).................................................... ............... 52

Typical Output Schematic: Actuator Control ............ 54

Typical Schematic: Condenser Fan, Anti-Corrosion Elec-

tric Heaters ................................................................ 55

Typical Output Schematic: VFD Control (SAF/RAF) 56 Typical Output Schematic: VFD Control Continued

(SAF/RAF)................................................................. 57

Typical Power Circuit Wiring - 4 Compressor - VFD 58 Typical Condensing Unit Control - MicroTech II - 4

Compressor................................................................. 60

Typical Super Mod Gas Furnace Control (1000 MBh) 64

Non-Chemical Water Treatment ................................ 66

Enthalpy Control ........................................................ 66

Hot Gas Bypass .......................................................... 68

External Time Clock................................................... 68

Smoke Detectors......................................................... 68

Freeze Protection........................................................ 68

Low Airflow Alarm.................................................... 69

Duct High Pressure Limit........................................... 69

Condensing Unit VFD Operation.... ........................... 69

Variable Frequency Drive Operation ......................... 69

Convenience Receptacle/Section Lights .................... 69

DesignFlow™ Outdoor Air Damper Option.............. 69

Propeller Exhaust Fan Option .................................... 72

Propeller Exhaust Fan Control ................................... 74

Ultraviolet Lights Option ........................................... 76

Ultraviolet Light Operation........................................ 76

Before Start-Up........................................................... 78

Power-Up.................................................................... 79

Fan Start-Up ............................................................... 79

Economizer Start-Up.................................................. 79

Evaporative Condenser Start-Up................................ 79

Compressor Start-Up.................................................. 80

Oil Pressure ................................................................ 81

Heating System Start-Up............................................ 81

Air Balancing.............................................................. 82

Sheave Alignment ...................................................... 82

Drive Belt Adjustment................................................ 83

Mounting and Adjusting Motor Sheaves.................... 83

Rooftop Equipment Warranty Regist. Form...................... 86

Planned Maintenance.............................................. .... 93

Sump Cleaning ............................. .............................. 95

Unit Storage................................................................ 95

Gas Furnace................................................................ 96

Bearing Lubrication.................................................... 96

Setscrews.................................................................... 98

Supply Fan Wheel-to-Funnel Alignment ................... 99

Refrigerant Charge ................................... .................. 99

Replacing Failed Refrigerant Sensors

or Switches ............................................................... 100

Evaporative Condenser Section................................ 100

Control Panel Components....................................... 101

Limited Product Warranty............................................... 104

Service and Warranty Procedure ..................... ................ 104

Replacement Parts .................................................... 104

Compressor....................................................... ........ 105

In-Warranty Return Material Procedure................... 105

Introduction

This manual provides general information about the “C” vintage McQuay RoofPak applied rooftop unit, models RDE and RPE. In addition to an overall description of the unit, it includes mechanical and electrical installation procedures, commissioning procedures, sequence of operation information, and maintenance instructions. For further information on the optional forced draft gas-fired furnace, refer to Bulletin No. IM 684 or IM 685.

The MicroTech II applied rooftop unit controller is available on “C” vintage applied rooftop units. For a detailed description of the MicroTech II components, input/output configurations, field wiring options and requirements, and service procedures, refer to IM696 for a description of operation and information on using and programming the MicroTech II unit controller, refer to the appropriate operation manual (see Figure 1).

For a description of operation and information on using the keypad to view data and set parameters, refer to the

appropriate program-specific operation manual (see Figure 1).

Table 1: Operation Manuals

Unit Manual

VFD’s Vendor IM Manuals

Discharge Air Control (VAV or CAV) OM 137

Space Comfort Control

(CAV-Zone Temperature Control)

Non-Chemical Water Treatment Option IM 827

OM 138

Introduction

Unit Nameplate

The unit nameplate is located on the outside lower right corner on the main control box door. It includes the unit model number, serial number, unit part number, electrical characteristics, and refrigerant charge.

Gas Burner Nameplate

On units which include gas heat, the nameplate is located on the lower right corner on the main control box door. It includes the burner model number, minimum/maximum input, maximum temperature rise and minimum CFM.

Hazard Identification Information

WARNING

Warnings are provided throughout this manual to indicate to installing contractors, operators, and service personnel potentially hazardous situatio n s wh i c h, if no t avo i d ed , ca n result in severe personal injury or property damage.

CAUTION

Cautions are provided throughout this manual to indicate to installing contractors, operators, and service personnel potentially hazardous situatio n s wh i c h, if no t avo i d ed , ca n result in personal injury or equipment damage.

Nomenclature

RoofPak

Unit Configuration

P = Blow through Cooling D = Draw through Cooling

Evaporative Condensers

Nominal Capacity (Tons)

RPE, RDE: 076, 089, 100, 110, 130, 140, 150

R P E - 150 C S E

Heat Medium

A = Natural Gas E = Electric S = Steam W = Hot Water Y = None (Cooling Only)

Cooling Coil Size

S = Standard (Low Airflow) L = Large (High Airflow)

Design Vintage

McQuay IM 791-2 3

Introduction

Unit Description

Typical Component Lo ca tio ns

Figure 1 shows a typical RPE unit with the locations of the

major components. Figure 2, page 4 shows a typical RDE unit

Figure 1: Typical Component Locations - RPE Units

with the locations of the major components. These figures are for reference only. See the certified submittals for actual specific dimensions.

Figure 2: Component Locations - RDE Units

4 McQuay IM 791-2

Condenser Fan Arrangement

Table 2 shows the condenser fan numbering conventions and

locations for each unit size.

Table 2: Condenser Fan Arrangement

Introduction

Unit Size

076C 089C 100C

110C 130C 140C 150C

Refrig. Circuit

Arrangement

Refrigerant Circuit Schematic

Figure 3: Circuit Schematic

Fan Control With VFD Without VFD

11, 21 - Digital 12 - CCB1 - B06 22 - CCB2 - B06

11, 21 - Digital 12 - CCB1 - B06 22 - CCB2 - B06 31 - CCB1 - B07 32 - CCB1 - B07

11, 21 - Digital 21 - CCB2 - B05 12 - CCB1 - B06 22 - CCB2 - B06

11 - CCB1 - B05 21 - CCB2 - B05 12 - CCB1 - B06 22 - CCB2 - B06 13 - CCB1 - B07 23 - CCB2 - B07

Legend

A Compressor A1 Second Compressor (4 Compressor Units) B Discharge Line C Condenser Coil D Evaporator Coil

E Manual Shut-off Valve

F Filter-Drier G Liquid Line Solenoid Valve H Sightglass I Liquid Line

J Suction Line K Thermostatic Expansion Valve L Distributor

M Combination Hot Gas Bypass Control and Solenoid Valve

N Hot Gas Bypass Lines (Optional)

McQuay IM 791-2 5

Introduction

Refrigeration Piping

This section presents the unit refrigeration piping diagrams for the various available configurations. Component numbering conventions are also shown.

Figure 4: Condenser Piping - 2 Compressors - 2 Circuits (076C - 100C)

1. Discharge Line Service Valve

2. Discharge Muffler

3. Liquid Line Manual Shut-off Valve

4. Suction Line Service Valve

5. Vibration Eliminator

Suction LIne Circuit 2 Circuit 1

Compressor 2

Discharge Line Circuit 2

Hot Gas Bypass Circuit 2 Circuit 1

Liquid Line Circuit 1

Liquid Line Circuit 2

With Vibration Eliminators

Compressor 1

Discharge Line Circuit 1

Suction LIne Circuit 2 Circuit 1

Compressor 2

Discharge Line Circuit 2

Hot Gas Bypass Circuit 2 Circuit 1

Liquid Line Circuit 1

Liquid Line Circuit 2

Compressor 1

Without Vibration Eliminators

Discharge Line Circuit 1

6 McQuay IM 791-2

Figure 4. Condenser Piping - 4 Compressors - 4 Circuits (110C - 150C)

1. Discharge Line Service Valve

2. Discharge Muffler

3. Liquid Line Manual Shut-off Valve

4. Suction Line Service Valve

5. Vibration Eliminator

Hot Gas Bypass Circuit 2 Circuit 1

Liquid Line Circuit 2

Liquid Line Circuit 1

Suction LIne Circuit 2 Circuit 1

Compressor 4

Compressor 2

Introduction

Discharge Line Circuit 2

Compressor 3

With Vibration Eliminators

Hot Gas Bypass Circuit 2 Circuit 1

Liquid Line Circuit 2

Liquid Line Circuit 1

Compressor 1

Suction LIne Circuit 2 Circuit 1

Discharge Line Circuit 1

Compressor 4

Compressor 2

Discharge Line Circuit 2

Compressor 3

Without Vibration Eliminators

Compressor 1

Discharge Line Circuit 1

McQuay IM 791-2 7

Introduction

Figure 5: Service Compartment Piping

Solid Core Filters

1. Liquid Line Solid Core Filter/Drier

2. Liquid Solenoid Valves

3. Hot Gas Bypass Valve and Solenoids

To Evaporator Coil

Liquid Line Circuit # 1 Circuit # 2

Suction Line Circuit # 2 Circuit # 1

Hot Gas Bypass Circuit # 1

Hot Gas Bypass Circuit # 2

To Compressors

Replaceable Filters

1. Liquid Line Replaceable Core Filter/Drier

2. Liquid Solenoid Valves

3. Hot Gas Control and Solenoid Valve

To Compressors

To Evaporator Coil

Liquid Line Circuit # 1 Circuit # 2

Suction Line Circuit # 2 Circuit # 1

Hot Gas Bypass Circuit # 1

Hot Gas Bypass Circuit # 2

8 McQuay IM 791-2

Spray System Plumbing with Optional Non-Chemical Water Treatment

WARNING

Failure to maintain and continually provide water treatment may result in severe equipment damage and may create biologically hazardous conditions. See

Figure 26 for water connection sizes and locations.

Figure 6: Spray System Piping

NOTE: The cyclone separator is on a side stream. A hand

valve controls water flow. The hand valve should be opened until the inlet pressure to the separator is about 12 psi as determined by the factory-installed gauge. This will yield about 20 gpm of blowdown whenever the blowdown solenoid opens.

Dolphin makeup water

Dolphin sump water treatment module

Dolphin sump water transformer

To Spraybar

transformer

Introduction

To Spraybar

Conductivity sensor

Conductivity controller

Makeup water control valve

Auto purge controller

Flowmeter

Cyclone seperator

Sump overflow

Ball valve actuators

Heat-tape all components from customer connection point to makeup water control valve

Dolphin makeup water treatment module

Makeup water connection point to sump tank.

Cleanout

Customer makeup water connection point

Manual shutoff

Sump Pump

McQuay IM 791-2 9

Freeze protection valve and actuator

Blow down and drain

Introduction

Bleed Off and Water Consumption

Controlled bleed off [or blow down] is required on McQuay RPE/ RDE units as it should be with all evaporative condensing products. It involves draining off a portion of the highly concentrated water from the bottom of the sump and replacing it with lower concentration make-up water to inhibit scale. Scale protection is required because the evaporation process leaves behind solids (scale) that will coat the heat exchanger surfaces and sump. This reduces the capacity, efficiency, and life expectancy of the equipment.

Manual bleed off occurs whenever the spray pump operates. A manual valve adjusts flow and is provided as standard. Refer to Figure 6. This inevitably bleeds off too much [increased water costs] or too little [risking scale build up] water. Automatic bleed off control is superior and usually is provided with the water treatment system.

Theoretical water consumption required for proper heat rejection is 1.8 gallons per ton hour. All of this water evaporates and none goes into the sewer. An additional 0.6 to

0.9 gallons per ton hour (.03 to .05 with McQuay nonchemical water treatment) is also required for make up and bleed off. The exact amount should be determined by water

Figure 7: Control Locations - RPE Units

analysis. The RPE/ RDE includes a float valve and solenoid that automatically refills the sump as required.

Bleed off must be handled in accordance with local codes and normally is drained into the sanitary sewer. Normally, this water should not be drained onto the roof or into a storm drain. One possible exception to this is with the McQuay nonchemical water treatment option (consult local codes carefully). Because most water utilities charge for both intake and sewer water flows based on intake meter readings, sewer charges may be reduced if sewer flow is proven to be less than water intake. McQuay offers both intake and bleed off water meters to document reduced sewer flow [confirm details with your local utility]. These meters are not included in the basic water treatment option.

Control Locations

Figure 7 (RPE Units) and Figure 8, page 11 (RDE Units) show

the locations of the various control components mounted throughout the units. See Control Locations‚ page 10 for the locations of control components mounted in control panels. Additional information is included in Table 3, page 15 and the

Legend‚ page 47.

Return Air

Economizer

Heat

Section

Discharge

Plenum Section

HL22 (Optional)

LT10 (Optional)

S10, REC10 (Optional)

Service Section

SD1 (Optional)

Condensor

Section

VM1 (Optional)

Exhaust Fan

Water Treatment (Optional)

Oil Pressure Box

Water Pump

Control Box

Space Heater (Optional)

Water Level Switches (WL63, WL64)

Sump Heater (Optional)

Sump Water Temp Sensor

ACT5 (optional)

ACT6 (optional)

OAT

LT11

(Optional)

S11 REC11

OAE

RAE (optional)

10 McQuay IM 791-2

Figure 8: Control Locations - RDE Units

(

)

ondensor Section

Introduction

C19,20

(Optional)

Economizer

Return Air

Filter

Section

Heat

Section

SV1, 2

Supply Fan

Discharge

Plenum Section

OAE

OAT

Service Section

FS1

(Optional)

LT10 (Optional)

S10, REC10 (Optional)

SD1 (Optional)

Exhaust Fan

Water Treatment (Optional)

Water Pump

Control Box

Space Heater (Optional)

Sump Heater (Optional)

Sump Water Temp Sensor

Oil Pressure Box

Water Level Switches (WL63, WL64)

LT11 (Optional)

S11, REC11

SD2

Optional

McQuay IM 791-2 11

Introduction

Control Panel Locations

The unit control panels and their locations are shown in the following figures. These figures show a typical unit configuration. Specific unit configurations may differ slightly from these figures depending on the particular unit options. See Wiring Diagrams‚ page 47 for the Legend and component description.

Figure 9: Control Panel Locations - Service Compartment

WARNING

Electrical shock can cause severe personal injury or death.

The control panel must be serviced by trained, experienced technicians.

Oil Pressure Instruments

Control Panel

Power Disconnect

12 McQuay IM 791-2

Figure 10: Main Control Panel - 076C - 150C

Introduction

See page page 47 for Legend

for Control

Connections

Terminal Block

2 Feet to Floor

Main Disconnect

or Power Block

McQuay IM 791-2 13

Introduction

Figure 11: Electric Heat Control Panel - Sizes 075C- 135C

FB31FB32FB33

M31M32M33

FB34FB44

M34M44

FB41FB42FB43

M41M42M43

GLG3

DS3

H53

TB11

• The manual shutter is normally be closed but can be opened

to condition the compartment when service is needed.

Figure 12: Walk-In Service Compartment

Perform Most Refrigerant Service in Comfort, Away

From Compressor Noise

Marine Lights

Exhaust Fan

Optional Unit Heater

Walk-In Service Compartment

Each unit includes a walk-in service compartment containing the following:

• Main control panel. See Figure 9, page 12.

• Liquid Line components except the expansion valve.

• Spray pumps, water control valves (except float valves in the

sump) and water supply and sanitary connections. See

Figure 6, page 9.

• Water treatment system (optional).

• Main access door opened from the inside and outside.

• Raised service grate to help protect service personnel against

water and chemical spills.

• Refrigerant Schrader ports are provided on the liquid and

suction lines to allow for easy refrigerant pressure readings, however, discharge pressure at the compressor must be measured outside the enclosure.

• Refrigerant charge can be added at the Schrader connections

in the compartment.

• Lights, ventilation fans, manual shutter that can be opened to

allow conditioned air into the plenum and optional unit heater provide more comfortable servicing.

• An adjustable TC66 thermostat turns on the ventilation fan

when the compartment temperature exceeds 75°F.

• An adjustable integral thermostat runs the unit heater when

the compartment temperature drops to 35°F.

Charging, Suction, Discharge & Liquid Schrader Connections

Hot Gas Bypass Valves

Solenoid, Sight Glass & Filter Drier

Raised Floor Grate and Drain Pan

Space for Water Treatment

WARNING

Moving parts and electrical connections in the service compartment can cause severe personal injury or death.

Cabinet access must be limited to trained, experienced technicians only.

14 McQuay IM 791-2

Controls, Settings, and Functions

Introduction

Table 3 presents a listing of all the unit control devices.

Included in the table are the device symbol, a description of the device, its function, and any reset information, its location,

Table 3: Controls, Settings , an d Fu nc tions

Symbol

CS1 & 2

DAT

DHL

EFT

FP1, 2

FS1 Freezestat

HP1, 2,

3 & 4

LP1, 2

MCB Main control board Processes input information N/A

MP1–6 Compressor motor

OAE

OAT

PC5 Dirty filter switch Senses filter pressure drop Auto

PC6 Dirty filter switch Senses filter pressure drop Auto

Description Function Reset Location Setting Range Differential Part no.

Switch (toggle), refrigerant circuit

Discharge air temperature sensor

Duct high limit switch

Entering fan air temperature sensor

Evaporator frost protection

High pressure control

Low pressure control

protector

Enthalpy control (electromechanical)

Enthalpy control (electronic)

Outside air temperature sensor

Shuts off compressor control circuits manually

Senses discharge air temperature

Prevents excessive VAV duct pressures; shuts off fan

Senses entering fan air temperature

Senses low refrigerant temperature

Shuts off fans, opens heating valve, and closes outdoor damper if low air temperature at coil is detected

Stops compressor when refrigerant discharge pressure is too high

Stops compressor when suction pressure is too low (used for pumpdown)

Senses motor winding temperature, shuts off compressor on high temperature.

Notes:

1.Unit size 018C compressors include internal motor protector.

2.Unit sizes 020C–036C, circuit #1 compressors include internal motor protector (refer to unit wiring diagram).

Returns outside air dampers to minimum position when enthalpy is too high

Returns outside air dampers to minimum position when outside air enthalpy is higher than return air empalthy (use RAE)

Senses outside air temperature N/A N/A N/A 060004705

N/A

Auto

N/A

Auto Heating section

Manual

(relay

latched)

Auto Compressor

Auto at

3400

ohms

Auto

any device setting, any setting ranges, differentials, and the device part number.

Main control

panel

Discharge air

section

Main control

panel

Inlet of supply

fan

Return bends of

evaporative coil

Compressor

Main control

box

Compressor junction box

Economizer

section

Economizer

section

First filter

section

Final filter

section

N/A N/A N/A 01355000

N/A N/A 060004705

3.5" w.c

(871.8 Pa)

N/A N/A 060004705

Opens at

30°F

Closes at

45°F

38°F (3°C)

or as required

See

page 105.

See

page 105.

N/A N/A N/A 060006101

9 K–18 K

ohms

“B” or as

required

Fully CW past

“D”

(when used

with RAE)

As required

0.05–5.0" wc

(12.5–1245.4

Pa)

N/A N/A 072501901

35°F–45°F

(2°C–7°C)

N/A

700 ohms cold N/A 044691509

A–D

A–D N/A 049262201

.05-5" wc

(12.5–1245.4

Pa)

.05-5" wc

(12.5–1245.4

Pa)

.05" wc

(12.5 Pa),

fixed

12°F (7°C),

fixed

100 psi

(689 kPa)

25 psi

(172 kPa)

Temperature:

3.5°F (2°C) Humidity:

5% fixed

.05" wc

(12.5 Pa)

.05" wc

(12.5 Pa)

065493801

065830001

047356120

047356111

030706702

065493801

McQuay IM 791-2 15

Introduction

Table 3: Controls, Settings , an d Fu nc tions (continued)

Symbol

PC7

PS1, 2 Pumpdown switch

RAE

RAT

SD1

SD2

SPS1

SPS2

SUMP

HTR

SV1, 2

SV5, 6

SV61,

SV63 Solenoid Valve

SWT Sump Water Temp

S1 System switch

TC66 Temperature

WL63 Switch, Water Level

WL64 Switch, Low Water Maintains proper water level N/A Sump Holding

Description Function Reset Location Setting Range Differential Part no.

Airflow proving switch

Return air enthalpy sensor

Return air temperature sensor

Smoke detector, supply air

Smoke detector, return air

Static pressure sensor duct #1

Static pressure sensor duct #2

Static pressure sensor: building (space) pressure

Sump Water Heater , Evap Condenser

Solenoid valve (liquid line)

Solenoid valve (hot gas bypass)

Solenoid Valve (Water Fill - Evap Cond)

(Sump Drain - Evap Cond)

Sensor

ON-OFF-AUTO switch

Control - Evap Cond Exhaust Fan

Sump Fill

Senses supply fan pressure to prove airflow

Used to manually pump down compressor

Used to compare return air enthalpy to outside air enthalpy (used with OAE)

Senses return air temperature N/A Initiates unit shutdown if smoke

is detected Initiates unit shutdown if smoke

is detected Converts static pressure

signals to voltage signals Converts static pressure

signals to voltage signals and sends them to MicroTech II controller

Converts static pressure signals to voltage signals.

Controls Wa ter Temp in the Evap Condenser Sump

Closes liquid line for pumpdown

Closes hot gas bypass line for pump-down

Open when sump water level is

low to add water

Opens to drain sump N/A Service

Sensor for freeze and head

pressure control

Shuts off entire control circuit (except crankcase heaters)

Used to manually switch unit N/A

Sequences the vestibule

exhaust fan

Maintains proper water level N/A Sump Holding

Auto

N/A

Manual

N/A

N/A N/A Service

N/A Sump Holding

N/A

N/A Service

Supply fan

section

Condenser control box

Economizer

section

Return air

section

Discharge air

section

Return air

section

Main control

box

Main control

box

Main control

box

Sump Holding

Tank

Condenser

section

Condenser

section

Compartment

Tank

Main control

box

Main control

box

Compartment

Tank

.10" wc (25

Pa)

N/A N/A N/A 01355000

N/A N/A N/A 049262202

N/A N/A 060004705

N/A N/A N/A 04925001

N/A

N/A N/A N/A

N/A N/A N/A 111011001 N/A N/A N/A

N/A N/A N/A

N/A N/A N/A See parts

N/A N/A N/A 001355000

N/A N/A N/A N/A N/A N/A

N/A N/A N/A See parts

.05-5" wc

(12.5–1245.4

Pa)

0–5" wc

(0–1245.4 Pa)

1–6 VDC out

0–5" wc

(0–1245.4 Pa)

1–6 VDC out

-025–0.25" wc

(-62.3–62.3 Pa)

1–5 VDC out

.05" wc

(12.5 Pa),

fixed

N/A 049545007

N/A 049545006

060015801

See parts

catalog

16 McQuay IM 791-2

Mechanical Installation

The installation of this equipment must be in accordance with the regulations of authorities having jurisdiction and all applicable codes. It is the responsibility of the installer to

determine and follow the applicable codes.

WARNING

Improper installation, adjustment, alteration se r v ic e or maintenance can cause personal inju ry or death.

Read and understand this Installation and Maintenance manual thoroughly before installing or servicing this equipment.

Note: Low head pressure may lead to poor, erratic refrigerant

feed control at the thermostatic expansion valve. The units have automatic control of the condenser fans which should provide adequate head pressure control down to 50°F (10°C). The system designer is responsible for assuring the condensing section is not exposed to

excessive wind or air recirculation.

WARNING

Sharp edges and coil surfaces can cause personal injury. Avoid contact with them.

Installation and maintenance must be performed only by trained and experienced personnel familiar with local codes and regulations.

WARNING

Sharp edges on sheet metal, screws and clips can cause personal injury.

This equipment must be installed and operated only by experienced trained personnel.

Mechanical Installation

Receiving Inspection

When the equipment is received, check all items against the bill of lading to be sure all crates and cartons have been received. If the unit has become dirty during shipment

(winter road chemicals are of particular concern), clean it when received.

Inspect all units for damage when received. Report all shipping damage to the carrier and file a claim. In most cases, equipment is shipped F.O.B. factory and claims for freight damage should be filed by the receiver.

The unit nameplate should be checked before unloading the unit to make sure the voltage complies with the power supply available.

Unit Clearances

Service Clearance

Allow service clearance approximately as indicated in

Figure 13. Also, a roof walkway should be provided to the

rooftop unit and along at least the two sides of the unit that provide access to most controls and serviceable components.

NOTICE

On units with side discharge, access to plenum mounted components becomes difficult once ductwork is installed. Installer must provide access in the ductwork for plenum mounted controls.

Figure 13: Service Clearances Side Discharge

72" 4 sides except as indicated

ABCDEFG

24"

Roof Walkway

Adjacent to Cooling Coil, Heat, and Supply Fan Sections.

ervice Clearance on

Legend:

A = Return Air Section B = Filter Section C = Cooling Section D = Cooling/Supply Fan Section E = Heat Section F = Discharge Plenum Section G = Service Com

artment

72" Clearance to end of unit or en of outside hood

McQuay IM 791-2 17

Mechanical Installation

Maxi

All

Figure 14: Side Discharge

V entilation Clearance

Following are minimum ventilation clearance recommendations. The system designer must consider each application and provide adequate ventilation. If this is not done, the unit will not perform properly.

Unit(s) surrounded by a screen or a fence:

1 The bottom of the screen or fence should be at least 1 ft.

(305 mm) above the roof surface.

2 The distance between the unit and a screen or fence should

be as described in Service Clearance‚ page 17. See also

Figure 13, page 17.

3 The distance between any two units within a screen or

fence should be at least 120" (3048 mm).

Unit(s) surrounded by solid walls:

1 If there are walls on one or two adjacent sides of the unit,

the walls may be any height. If there are walls on more than two adjacent sides of the unit, the walls should not be higher than the unit.

2 The distance between the unit and the wall should be at

least 96" (2438 mm) on all sides of the unit.

3 The distance between any two units within the walls should

be at least 120" (3048 mm). Do not locate outside air intakes near exhaust vents or other sources of contaminated air.

If the unit is installed where windy conditions are common, wind screens should be installed around the unit, maintaining the clearances specified (see Figure 15). This is particularly important to prevent blowing snow from entering outside air intakes, and to maintain adequate head pressure control when mechanical cooling is required at low outdoor air temperatures.

Overhead clearance

1 Unit(s) surrounded by screens or solid walls must have no

overhead obstructions over any part of the unit.

2 The area above the condenser must be unobstructed in all

installations to allow vertical air discharge.

3 The following restrictions must be observed for overhead

obstructions above the air handler section (see Figure 15):

a There must be no overhead obstructions above the

furnace flue, or within 9" (229 mm) of the flue box.

b Overhead obstructions must be no less than 2" (51 mm)

above the top of the unit.

c There must be no overhead obstructions in the areas

above the outside air and exhaust dampers that are farther than 24" (610 mm) from the side of the unit.

Figure 15: Overhead Clearance

mum

owable

9" (229mm) Min to Flue Box Typical All Sides

24" (610 mm) Maximum

2" (51mm) Top of Unit To O verhead Obstruction

Overhead Canopy Area

Flue Box

18 McQuay IM 791-2

Mechanical Installation

Roof Curb Assembly and Installation

The roof curb and unit must be located on a portion of the roof that can support the weight of the unit. The unit must be supported to prevent bending or twisting of the machine.

If building construction could allow the transmission of sound and vibration into the occupied space, the unit should be

located over a non-critical area. It is the responsibility of the system designer to make adequate provisions for noise and vibration in the occupied space.

The curb and unit must be installed level to allow the condensate drain to flow properly.

Integral supply and return air duct flanges are provided with the RPE/RDE roof curb, allowing connection of ductwork to the curb before the unit is set. The gasketed top surface of the duct flanges seals against the unit when it is set on the curb. These flanges must not support the total weight of the ductwork. Refer to Installing Ductwork‚ page 32 for details on duct connections. It is critical that the condensate drain side of the unit be no higher than the opposite side.

Assembly of a typical RPE/RDE roof curb is shown in

Figure 17, page 21. Parts A through K are common to all units

having bottom return openings. Depending on the unit length, Parts L and M may be included with the roof curb kit to create the correct overall curb length.

RPE/RDE Assembly instructions

Refer to Figure 17, page 21.

1 Set curbing parts A through K per dimensions shown over

roof opening or on a level surface. Note location of return and supply air openings.

2 If applicable, set other curbing parts (D, L, M, etc.) in place

making sure that the orientation complies with the assembly instructions. Check alignment of all mating bolt holes.

3 Bolt curbing parts together using fasteners provided.

Tighten all bolts finger tight.

4 Square entire curbing assembly and securely tighten all

bolts.

5 Position curb assembly over roof openings. Curb must be

level from side to side and over its length. Check that top surface of the curb is flat with no bowing or sagging.

6 W eld curbing in place. Caulk all seams watertight. Remove

backing from 0.25" (6 mm) thick x 1.50" (38 mm) wide gasketing and apply to surfaces shown by notes.

7 Flash curbing into roof as shown in Detail “B”. 8 Parts E and F are not required on units with no return shaft

within the curb perimeter.

9 Parts G and H are not required on units with no supply shaft

within the curb perimeter.

McQuay IM 791-2 19

Mechanical Installation

Figure 16: RPE/RDE Roof Curb Assembly

RDE & RPE 076-100

OPENING

SEE FIGURE "A"

RDE & RPE 110-150

OPENING

SEE FIGURE "A"

Dim 076-100C 110-150C

100.00 100.00

84.00 60.00

62.00 62.00

38.00 46.00

87.00 87.00

1.50 1.50

6.80 6.80

81.00 81.00

7.50 7.50

5.00 5.00

8.00 8.00

2.00 2.00

4.00 4.00

1.50 1.50

78.80 78.80

B C D E F G H

K L M N P Q R

20 McQuay IM 791-2

Figure 17: RPE/RDE Roof Curb Assembly

Using remaining side supports in this area, align lengths on opposite sides of assembly and install a cross support at each side.

Equal Length Side Supports

See Detail "A"

Mechanical Installation

Condenser

Section Support

(1 of 2 shown)

38.8"

Return

Air

85"

62.8"

Section B-B

Section A-A

1. Unit Base

2. Curb Gasketing

3. 2 x 4 Nailer Strip

4. Galvanized Curb

5. Duct Support

6. Cant Strip (not furnished)

7. Roofing Material (not furnished)

8. Rigid Insulation (not furnished)

9. Counter flashing (not furnished)

10. Flashing (not furnished)

McQuay IM 791-2 21

Mechanical Installation

Post and Rail Mounting

When mounting by post and rail, the structural support should be run the full length of the unit. Locate the structural member at the base of the unit as shown in Figure 18 assuring the

shaded area is well supported by the structural member.

CAUTION

The unit must be level side to side and over the entire length. Equipment damage can result if the unit is not level.

If resilient material is placed between the unit and the rail, insert a heavy steel plate between the unit and the resilient material to distribute the load. Properly seal cabinet penetrations (electrical, piping, etc.) to protect against moisture and weather.

Figure 18: Post and Rail Mounting

max

4 Provide adequate protection from vandalism, mechanical

contact, etc.

5 Securely close the doors. 6 If there are isolation dampers, make sure they are properly

installed and fully closed to prevent the entry of animals and debris through the supply and return air openings.

7 Cover the supply and return air openings on units without

isolation dampers.

Figure 19 shows an example of the rigging instruction label

shipped with each unit.

WARNING

Use all lifting points. Severe personal injury and property damage can result from improp er lifting adjustment.

Figure 19: Rigging and Handling Instruction Label

Rigging and Handling Instructions

Unit has either four or six lifting points (four-point shown below).

Caution: All lifting points must be used.

Rigging cables must be at least as long as distance "A".

Note:

*Rail cannot extend beneath the unit more than 5" (127 mm) or it will interfere with duct and electrical connections.

Rigging and Handling

Lifting brackets with 2" (51 mm) diameter holes are provided on the sides of the unit.

Use spreader bars, 96" to 100" (2438 to 2540 mm) wide to prevent damage to the unit cabinet. Avoid twisting or uneven lifting of the unit. The cable length from the bracket to the hook should always be longer than the distance between the outer lifting points.

If the unit must be stored at the construction site for an intermediate period, these additional precautions should be taken:

1 Make sure to support the unit well along the length of the

base rail.

2 Make sure to level the unit

(no twists or uneven ground surface).

3 Provide proper drainage around the unit to prevent flooding

of the equipment.

Caution:

Lifting points may not be symmetrical to center of gravity of unit. Balast or unequal

Lift Only As Indicated

cable lengths may be required

Lifting Points

Refer to Figure 20 and the following calculations to determine whether a four or six point lift is required.

X= Distance from the entering air end of the unit (or shipping section) to the first lifting lug in the direction of air flow.

For all units or shipping sections with outdoor air/return air options, X= 48"

For shipping sections without outdoor air/return air options,

X= 0 Y= distance from condenser or leaving air end of unit to the

last lifting lug. For all units or shipping sections with condensers, Y= 21.5

(sizes 76-100) or Y= 60.2 (sizes 110-150). For all units or shipping sections without condensers, Y=0 Z= Total base rail length of the unit. Note: Z excludes hoods

and overhung parts extending past base rails of the unit.

22 McQuay IM 791-2

Mechanical Installation

A= Z-X-Y If A<288", 4-point lift is sufficient If A>288", 6-point lift is required B= Distance from first lifting lug to middle lifting lug on units

with 6-point lift. B= A/2 +/- 48" Note: Middle lifting lug may be installed on

either side of the midpoint to avoid interference with condensate drains.

Figure 20: Unit Type RPE/RDE Lifting Points

Figure 21: RPE/RDE Factory Split at Supply Fan Section

McQuay IM 791-2 23

Mechanical Installation

Reassembly of Split Units

Although RoofPak units typically ship from the factory as complete units, they may be split at the factory.

The RPE/RDE unit may ship from the factory as two pieces, split at the supply fan bulkhead, to be recoupled together on the roof. This configuration would be ordered if shipping length or weight limitation prevented a packaged RPE/RDE from being ordered. Splitting at the fan has the advantage of leaving all factory refrigerant piping intact so field evacuation and charging is not required.

A single nameplate is attached to the air handler section and power is fed to both sections through the main control box, as it would be in a non-split RPE/RDE unit.

RPE/RDE Factory Split at Fan

Field reassembly of an RPE/RDE unit that has shipped split at the fan takes place in two phases:

Phase 1 - Setting the Sections and Cabinet Reassembly

The steps required to set the unit and reassemble the cabinet are shown in Figure 22, Figure 23, and Figure 24, page 25. The following items should be noted:

1 Top cap and plywood covers must be removed before the

sections are set together, but the steel retainer clips must be left in place to secure the bulkhead. Refer to Step 1 and

Figure 22.

2 Both sections must be carefully lowered into place to make

sure that the roof curb engages the recesses in the unit base.

3 All seams at the split must be caulked watertight after

recoupling the sections, as shown in Step 3 and Figure 23,

page 25.

WARNING

Improper installation can cause severe equipment damage, personal injury or death.

Connect the power block correctly and maintain proper phasing.

When reconnection of the power wires is complete, the inner raceway cover in the blank or heat section must be reinstalled.

Figure 24, page 25 shows a typical installation of the raceway

cover. If the unit is equipped with a fan diffuser, install as shown in Figure 24.

Control harnesses can be run by removing the external raceway covers on either side of the unit split. The excess harness length can be removed from the external raceway on the DX side of the split, routed along the raceway through the bushed hole in the fan section and into the junction box where control wiring terminal blocks are provided for reconnection. All electrical connections should be made per the unit's electrical schematics. Reinstall the external raceway covers after routing of the control wires is complete.

1 Prepare the units for reassembly as shown in Figure 22.

Figure 22: RPE/RDE Split at Fan Reassembly - Step 1

R e m o v e p l y w o o d a n d r e t a i n i n g

R e m o v e t o p c a p a n d s a v e f o r s t e p 3

a n g l e s f r o m u n i t a n d d i s c a r d

D i s c h a r g e e n

d o f U n i t

Phase 2 - Reconnecting Power and Control Wiring

The DX coil/condenser section contains power and control harnesses which have their excess length in the blank or heat section that is normally immediately downstream of the fan. Once the sections are physically reconnected, the ends of the

F a n e n d o f U n i t

power harness are fed back through the unit base into the junction box, per the unit’s electrical schematics.

24 McQuay IM 791-2

Set fan end of unit and discharge end of unit in place.

3 Caulk and install parts as shown in Figure 23.

R e m o v e s c r e w s o n f a n p a n e l , b u t l e a v e r e t a i n e r c l i p s i n p l a c e ; s a v e s c r e w s f o r

S t e p 3 .

Mechanical Installation

ovided

Figure 23: Split at Fan Reassembly - Step 3

Reinstall Top Cap Saved from Step 1

Caulk Ends of Splice Cap

Splice Cover Provided

Install #10 Screws Provided

Figure 24: RPE Split at Fan Reassembly - Step 4

Install Screws (.250-20 x .75) Saved from Step 1

Nut Clip-on Pr

Make electrical connections and reinstall Inner Raceway Cover as shown in Figure 24.

McQuay IM 791-2 25

Mechanical Installation

Condensate Drain Connection

The unit is provided with a 1.5" male NPT condensate drain connection. Refer to certified drawings for the exact location. The unit and drain pan must be level side to side and a P-trap must be installed for proper drainage.

RPE units may have positive or negative pressure sections. Traps should be used in both cases, with care given to negative pressure sections. In Figure 25, page 26, dimension “A” should be a minimum of 8" (203 mm). So the cabinet static pressure does not blow or draw the water out of the trap and cause air leakage, dimension A should be two times the maximum static pressure encountered in the coil section in inches w.c.

Drainage of condensate directly onto the roof may be acceptable; refer to local codes. A small drip pad of stone, mortar, wood or metal be should be provided to protect the roof against possible damage.

If condensate is to be piped into the building drainage system, the drain line should be pitched away from the unit at a minimum of 1/8" per foot. The drain line must penetrate the roof external to the unit. Refer to local codes for additional requirements. Sealed drain lines require venting to provide proper condensate flow.

Where the cooling coils have intermediate condensate pans on the face of the evaporator coil, copper tubes near both ends of the coil provide drainage to the main drain pan. Check that the copper tubes are in place and open before the unit is put into operation.

Because drain pans in any air conditioning unit will have some moisture in them, algae, etc. will grow. Periodic cleaning is necessary to prevent this buildup from plugging the drain and causing the drain pan to overflow. Also, the drain pans should be kept clean to prevent the spread of disease. Cleaning must

be performed by qualified personnel.

WARNING

Clean drain pans regularly. Growth in uncleaned drain pans can cause disease.

Cleaning must be done by trained, experienced personnel.

Figure 25: Condensate Drain Connection

S e e V i e w " A "

C o p p e r T u b e

( o n e e a c h e n d o f c o i l )

S t a t i c P r e s s u r e " P "

4 " ( 1 0 2 m m )

M i n i m u m

" A "

8 " ( 2 0 3 m m )

M i n . o r 2 x " P "

( i n . w . o . )

D r a i n P a n

N o t e : D r a i n l i n e m u s t

n o t b e r u n h i g h e r

t h a n t h i s l e v e l

M i n i m i z e T h i s

e n s i o n

D i m

Unit Piping

Gas Piping

See the “Installation” section of the gas-fired furnace installation manual, Bulletin No. IM684 or IM685.

Supply Water

City water must be piped into the service section of the unit. Install a manual shutoff valve to facilitate service of the unit. Provisions have been made to pipe through the floor of the service section within the curb. If the unit will be exposed to low outdoor air conditions, care must be taken to prevent freeze damage to this piping.

The service section has an optional heater to minimize freeze problems during cold weather. Verify that this heater functions before filling the unit. A sump heater option is also offered that includes heat tape on the pressure side of the float controlled fill valve, plus an extra 8 feet of heat tape to protect field connections inside the service compartment.

If the unit is mounted on post and rail structure, pipe will be exposed to outdoor conditions and will need to be heat taped or drained manually during the winter season.

26 McQuay IM 791-2

Mechanical Installation

Drain Water

A drain and bleed off connection is also located in the service section of the unit. Since this water will contain water treatment chemicals, local codes may require connection to the sanitary sewer. The freeze warning for supply water also applies to drain water piping.

Figure 26: Unit Piping Knockout Locations

Discharge

Air

Opening

7.87

6.88

9.26

DETAIL A

SCALE 1 : 9

4.75

2.25

6.75

4.75

Note: Make sure that a service compartment heater and

especially a sump heater or some type of freeze protection have been provided if freezing conditions are expected.

Walk-in

Vestibule

CONTROL WIRING .88" KNOCKOUT (3)

C ondensing

SUPPLY WATER

3.0" KNOCKOUT (.75" COPPER CONN ECTION)

Unit

7.87

26.50

DETAIL B

SCALE 1 : 9

21.50

3.0" KNOCKOUT (2)

Water Treatment

WARNING

Failure to maintain and continually provide water treatment will result in severe equipment damage and may create biologically hazardous conditions.

Water treatment, whether ordered as an option on the unit or purchased separately, must be properly installed and started before starting the unit. Failure to do so will result in scale build up on the condenser tubes with a resulting loss in heat rejection capacity. In severe cases, it may become impossible to operate the compressors. In addition, untreated cooling tower water can be a source for airborne disease.

Proper water treatment must include the following minimum features:

• Bleed Off

• Scale and corrosion inhibitor chemical treatment

• Biocide chemical treatment

See Catalog 219 for information on the optional McQuay supplied water treatment systems.

POWER WIRES

72.00

(REFERENCE)

DRAIN WATER

3.0" KNOCKOUT (2.0" PVC C ONNEC TION)

Hot Water Coil Piping

Hot water coils either are provided without valves for field piping or are piped with three-way valves and actuator motors. Note: If the unit is equipped with an iron valve, connecting to a copper piping system will likely cause galvanic corrosion to occur and the valve will not last. All coils have vents and drains factory installed.

Hot water coils are not normally recommended for use with entering air temperatures below 40°F (4°C). No control system can guarantee a 100% safeguard against coil freeze-up. Glycol solutions or brines are the only freeze-safe media for operation of water coils at low entering air temperature conditions.

When no factory piping or valve is included, the coil connections are 2-1/8" copper (two supply and two return). With the factory piping and valve package, field piping connections are the same NPT size as the valve with female threading (see Figure 27, page 28).

Refer to the certified drawings for the recommended piping entrance locations. All piping penetrations must be sealed to prevent air and water leakage.

Note: The valve actuator spring returns to a stem down

position upon power failure. This allows full flow through the coil.

McQuay IM 791-2 27

Mechanical Installation

CAUTION

Coil freeze possible. Possible equipment damage. Carefully read and follow instructions for mixing antifreeze solution. Some products will have higher freezing points in their natural state than when mixed with water. The freezing of coils is not the responsibility of McQuay International.

Figure 27: Hot Water Valve Package

R e t u r n

Figure 28: Hot Water Heat Section (Factory Valve/Piping)

B y p a s s

S u p p l y

Refer to the certified drawings for the recommended piping entrance locations. All piping penetrations must be sealed to prevent air and water leakage.

Note: The valve actuator spring returns to a stem up position

upon power failure. This allows full flow through the coil.

Steam Piping Recommendations

1 Be certain that adequate piping flexibility is provided.

Stresses resulting from expansion of closely coupled piping and coil arrangement can cause serious damage.

2 Do not reduce pipe size at the coil return connection. Carry

return connection size through the dirt pocket, making the reduction at the branch leading to the trap.

3 Install vacuum breakers on all applications to prevent

retaining condensate in the coil. Generally, connect the vacuum breaker between the coil inlet and the return main. However, if the system has a flooded return main, the vacuum breaker should be open to the atmosphere and the trap design should allow venting of large quantities of air.

4 Do not drain steam mains or takeoffs through coils. Drain

mains ahead of coils through a steam trap to the return line.

5 Do not attempt to lift condensate. 6 Pitch all supply and return steam piping down a minimum

of 1" (25 mm) per 10 feet (3 m) of direction of flow.

Steam Coil Piping

Steam coils either are provided without valves for field piping, or are piped with two-way valves and actuator motors.

The steam coil is pitched at 1/8" (3 mm) per foot (305 mm) to provide positive condensate removal. When no factory piping or valve is included, the coil connections are 2.5" male NPT iron pipe.

With the factory piping and valve package, the field supply connection is the same NPT size as the valve with female threading (see Figure 30, page 29).

Steam Trap Recommendations

1 Size traps in accordance with manufacturers'

recommendations. Be certain that the required pressure differential will always be available. Do not undersize.

2 Float and thermostatic or bucket traps are recommended for

low pressure steam. Use bucket traps on systems with onoff control only.

3 Locate traps at least 12" (305 mm) below the coil return

connection.

4 Always install strainers as closely as possible to the inlet

side of the trap.

5 A single tap may generally be used for coils piped in

parallel, but an individual trap for each coil is preferred.

Steam Coil Freeze Conditions

If the air entering the steam coil is below 35°F (2°C), note the following recommendations:

1 1.5 psi (34.5 kPa) steam must be supplied to coils at all

times.

2 Do not use modulating valves. Control should be by means

of face and bypass dampers.

3 As additional protection against freeze-up, the tap should

be installed sufficiently far below the coil to provide an adequate hydrostatic head to provide removal of condensate during an interruption on the steam pressure. Estimate 3 ft. (914 mm) for each 1 psi (7 kPa) of trap differential required.

28 McQuay IM 791-2

Mechanical Installation

4 If the unit is to be operated in environments with possible

freezing temperatures, an optional freezestat is recommended. See Freeze Protection‚ page 68 for additional information.

Figure 29: Valve Assembly

S t e m C l i p

S t e m

S e t s c r e w s

Figure 30: Steam Valve Package

Condensate

Figure 31: Steam Heat Section (Factory Valve/Piping)

McQuay IM 791-2 29

Mechanical Installation

Damper Assemblies

The optional damper assemblies described in this section are provided with manually adjustable linkages, or may be shipped with factory installed actuators and linkages.

Economizer Dampers

Outside air intake is provided on both sides of the unit, and the return air path is at the center of the damper set. As the single actuator modulates the outside air dampers open, the return air dampers close. Exhaust air exits the unit through the gravity relief dampers provided at the end of the economizer section.

The outside air return air damper assembly (economizer) comes with manually adjustable linkage. This adjustable linkage can also be used for connection of a damper operator.

The damper is set so that the crankarm moves through a 90degree angle to bring the economizer dampers from full open to full close. Mechanical stops have been placed in the crankarm mounting bracket. Do not remove stops. If the crankarm is driven past the stops, damage to the linkage or damper will result. The unit will ship with a shipping bolt securing the linkage crankarm. Remove shipping bolt before use.

Figure 32: Damper Adjustment

O u t s i d e

O p t i o n a l R e t u r n A i r F a n

A i r

E c o n o m i z e r

S h a f t . 5 0 0 D i a .

x 1 . 5 0 L o n g

O A

O p e n

9 0 °

S t r o k e

. 7 5

. 2 5

3 . 0 0

O A

C l o s e d

Note: For good airflow control, adjust linkages so damper

blades do not open beyond 70 degrees. Opening a damper blade beyond 70 degrees has little effect on its airflow. Do not “overclose” low leak damper blades. The edge seal should just lightly contact the adjoining blade. The blades will lock up if they are closed so far the seal goes over center.

30 McQuay IM 791-2

Mechanical Installation

Intake Hood Damper (0 to 100% outside air)

Units requiring 100% outside air are provided with a rain hood and dampers which may be controlled by a single actuator. The actuator provides two-position control for opening the dampers fully during unit operation and closing the dampers during the off cycle. No unit mounted exhaust dampers are provided.

Intake Hood Damper (0 to 30% outside air)

These dampers are intended to remain at a fixed position during unit operation, providing fresh air quantities from 0 to 30% of the total system airflow, depending on the damper setting. This setting is made at the linkage rod on units with manually adjustable linkages.

On units provided with MicroTech II controls, the damper position may be set at the controller keypad. During unit operation, the two-position actuator drives the damper to the position set on the keypad. During the off cycle, the damper is automatically closed.

No unit mounted exhaust dampers are provided with this option.

Figure 33: Intake Hood Damper Adjustment

Figure 34: Typical Damper Linkage Bar - Size 015C - 040C Shown

A i r f l o w

3 . 1 5 " ( 8 0 m m ) M a x . S t r o k e o f D a m p e r L i n k a g e B a r

Cabinet Weatherproofing

This unit ships from the factory with fully gasketed access doors and cabinet caulking to provide weather resistant operation. After the unit has been set in place, all door gaskets should be inspected for shipping damage and replaced if necessary.

S h a f t . 5 0 0 D i a .

x 1 . 5 0 L o n g

O A

O p e n

9 0 °

S t r o k e

. 7 5

The unit should be protected from overhead runoff from overhangs or other such structures.

Field assembled options such as external piping or vestibules must be recaulked per the installation instructions provided with the option.

O A

C l o s e d

. 2 5

3 . 0 0

McQuay IM 791-2 31

Mechanical Installation

Installing Ductwork

On bottom-supply/bottom-return units, the installing contractor should make an airtight connection by attaching field fabricated duct collars to the bottom surface of either the roof curb's duct flange or the unit's duct opening if a McQuay roof curb is not used. Do not support the total weight of the ductwork from the unit or these duct flanges. Refer to

Figure 35.

Units with optional back return or side discharge have duct collars provided. The discharge duct collars on a side discharge unit are exposed by removing the plenum section access door and the door gasketing.

Use flexible connections between the unit and ductwork to avoid transmission of vibration from the unit to the structure.

Figure 35: Installing Ductwork

U n i t D u c t O p e n i n g

Design ductwork per ASHRAE and SMACNA recommendations to minimize losses and sound transmission.

Where return air ducts are not required, connect a sound absorbing T or L to the unit return to reduce noise transmission to the occupied space.

Ductwork exposed to outdoor conditions must be built in accordance with ASHRAE and SMACNA recommendations

and local building codes

NOTICE

Installer must provide access in the ductwork for plenum mounted controls. On units with side discharge, access to plenum mounted components becomes difficult once ductwork is installed.

U n i t B a s e

F l e x i b l e

C o n n e c t o r

D u c t w o r k

9 . 7 6 "

4 . 5 8 "

R o o f C u r b

D u c t F l a n g e r i n R o o f C u r b

32 McQuay IM 791-2

Installing Duct Static Pressure Sensor Taps

Mechanical Installation

For all Variable Air Volume (VAV) units, duct static pressure taps must be field installed and connected to the pressure sensors in the unit. Sensor SPS1 is standard; additional sensor SPS2 is optional. These sensors are located at the bottom of the main control panel next to terminal block TB2 (see Control

Panel Locations‚ page 12).

The duct static pressure sensing tap must be carefully located and installed. Improper location or installation of the sensing tap will cause unsatisfactory operation of the entire variable air volume system. Following are pressure tap location and installation recommendations. The installation must comply with local code requirements.

CAUTION

Sensor fittings are fragile. Damage to pressure sensor can occur during removal.

If tubing must be removed from a pressure sensor fitting, use care. Do not wrench the tubing back and forth to remove or the fitting may break off.

1 Install a tee fitting with a leak-tight removable cap in each

tube near the sensor. This will facilitate connecting a manometer or pressure gauge if testing is required.

2 Use different colored tubing for the duct pressure (HI) and

reference pressure (LO) taps, or tag the tubes.

3 Locate the duct pressure (HI) tap near the end of a long

duct to ensure that all terminal box take-offs along the run will have adequate static pressure.

4 Locate the duct tap in a nonturbulent flow area of the duct.

Keep it several duct diameters away from take-off points, bends, neckdowns, attenuators, vanes, or other irregularities.

5 Use a static pressure tip (Dwyer A302 or equivalent) or the

bare end of the plastic tubing for the duct tap. (If the duct is lined inside, use a static pressure tip device.)

6 Install the duct tap so that it senses only static pressure (not

velocity pressure). If an L-shaped pressure tip device is used, the point must face the airstream. If a bare tube end is used, it must be smooth, square (not cut at an angle), and perpendicular to the airstream. (see Figure 36).

7 Locate the reference pressure (LO) tap somewhere near the

duct pressure tap within the building (see Figure 36). If the reference tap is not connected to the sensor, unsatisfactory operation will result.

8 Route the tubes between the curb and the supply duct, and

feed them into the unit through the knockout in the bottom

of the control panel (see Figure 16). Connect the tubes to the appropriate 1/8" fittings on the sensors. Make sure that the sensors do not support the weight of the tubing; use tube clamps or some other means.

Figure 36: Pressure Sensing Tub ing Ins t a lla tio n

To Sensor "HI" input

Duct Pressure Tap

Tubing Extends thru Approx. 1/8"

To Sensor "LO" Input

Pressure Sensing Tubin

Rubber Grommet

Lab Pressurization Applications

1 Install a “T” fitting with a leak-tight removable cap in each

tube near the sensor. This will facilitate connecting a manometer or pressure gauge if testing is required.

2 Use different colored tubing for the controlled space

pressure (HI) and reference pressure (LO) taps, or tag the tubes.

3 Regardless of whether the controlled space is positive or

negative with respect to its reference, locate the HI pressure tap in the controlled space. (The setpoint can be set between -0.2 and 0.2" W.C.)

4 Locate the reference pressure (LO) tap in the area

surrounding the controlled space. If the reference tap is not connected to the sensor, unsatisfactory operation will result.

5 Locate both taps so that they are not influenced by any

source of moving air (velocity pressure). These sources may include air diffusers or doors between the high and low pressure areas.

6 Route the tap tubes between the curb and the supply duct,

and feed them into the unit through the knockout in the bottom of the control panel (see Figure 36).

7 Connect the tubes to the appropriate 1/4" fittings on sensor

SPS2. Assure that the sensor does not support the weight of the tubing; use tube clamps or some other means.

McQuay IM 791-2 33

Mechanical Installation

Installing Building Static Pressure Sensor Taps

If a unit has direct building static pressure control capability, static pressure taps must be field installed and connected to pressure sensor SPS2 in the unit. This sensor is located at the bottom of the main control panel next to terminal block TB2 (see Control Locations‚ page 10).

The two static pressure sensing taps must be carefully located and installed. Improper location or installation of the sensing taps will cause unsatisfactory operation. Following are pressure tap location and installation recommendations for both building envelope and lab, or “space within a space” pressure control applications. The installation must comply

with local code requirements.

CAUTION

Fragile sensor fittings. May damage pressure sensor.

If tubing must be removed from a pressure sensor fitting, use care. Do not wrench the tubing back and forth to remove or the fitting may break off.

Building Pressurization Applications

Install a tee fitting with a leak-tight removable cap in each tube near the sensor. This will facilitate connecting a manometer or pressure gauge if testing is required.

2 Locate the building pressure (Hi) tap in the area that

requires the closest control. Typically, this is a ground level floor that has doors to the outside.

3 Locate the building tap so that it is not influenced by any

source of moving air (velocity pressure). These sources may include air diffusers or outside doors.

4 Route the building tap tube between the curb and the

supply duct, and feed it into the unit through the knockout in the bottom of the control panel.

5 Connect the tube to the 1/4" HI fitting on sensor SPS2.

Assure that the sensor does not support the weight of the tubing; use tube clamps or some other means.

6 Locate the reference pressure (LO) tap on the roof. Keep it

away from the condenser fans, walls, or anything else that may cause air turbulence. Mount it high enough above the roof so that it is not affected by snow, If the reference tap is not connected to the sensor, unsatisfactory operation will result.

7 Use an outdoor static pressure tip (Dwyer A306 or

equivalent) to minimize the adverse effects of wind. Place

some type of screen over the sensor to keep out insects. Loosely packed cotton works well.

8 Route the outdoor tap tube out of the main control panel

through a small field-cut opening in the edge of the control wiring raceway cover. Cut this “mouse hole” in the vertical portion of the edge. Seal the penetration to prevent water from entering. Connect the tube to the 1/4" LO fitting on sensor SPS2.

Electrical Installation

Field Power Wiring

Wiring must comply with all applicable codes and ordinances and these specifications. Defects caused by incorrect wiring are not covered by the warranty. An open fuse or motor protector indicates a short, ground, or overload. Before replacing a fuse or restarting a compressor or fan motor, the trouble must be found and corrected.

According to the National Electrical Code, a disconnecting means must be located within sight of and readily accessible from the air conditioning equipment. The unit may be ordered with an optional factory mounted disconnect switch. This switch is not fused. Power leads must be over-current protected at the point of distribution. The maximum allowable overcurrent protection is shown on the unit nameplate.

RPE and RDE units are provided with internal power wiring (see A, B, and C in Figure 37) for single or dual point power connection. The power block or an optional disconnect switch (see D in Table 37) is located per Table 4. Field power leads are brought into the unit through 3" knockouts in the bottom of the main control panel. Refer to the unit nameplate to determine the number of power connections.

Units ordered with multiple point power connections are provided with non-fused, factory mounted disconnect switches. Several multiple point power options are available,

as shown in Table 4.

WARNING

Hazardous voltage. Can cause severe injury or death.

Lock and tag out all electric power before servicing equipment. More than one disconnect may be required to de-energize the unit.

Table 4: Multiple Point Power Connection Options

Number of Electrical Circuits Disconnect Designation Load Location (see Figure 1)

Note: Refer to certified drawings for dimensions to wire entry

points.

34 McQuay IM 791-2

DS2 Supply & return fan motors, controls Main control panel DS1 Balance of unit Main control panel DS3 Electric heat Electric heat control panel DS1 Balance of unit Main control panel DS3 Electric heat Electric heat control panel DS2 Supply & return fan motors, controls Main control panel DS1 Balance of unit Main control panel

Figure 37: RPE and RDE Power Wiring

Vertical Power Connection

Mechanical Installation

Remove Covers

Fixed Panel

Access Door

Drill Hole Fixed Panel Horizontal Power Connection

Vertical Power Connection Through

Curb

Conceptual Power Wire Routing

for Both Horz. and Vert. Power

Connections

2 Power Knockouts

3 Control Knockouts

Terminal Block

for Control Connections

Location of Terminal Block or

Main Disconnect

2 Feet to Floor

or Power Block

Disconnect Power Lugs

McQuay IM 791-2 35

Mechanical Installation

The minimum circuit ampacity (wire sizing amps) is shown on the unit nameplate. Refer to Table 5, page 36 for the recommended number of power wires.

Copper wire is required for all conductors. Size wires in accordance with the ampacity tables in Article 310 of the National Electrical Code. If long wires are required, it may be necessary to increase the wire size to prevent excessive voltage drop. Wires should be sized for a maximum of 3% voltage drop. Supply voltage must not vary by more than 10% of nameplate. Phase voltage imbalance must not exceed 2%. (Calculate the average voltage of the three legs. The leg with voltage deviating the farthest from the average value must not be more than 2% away.) Contact the local power company for correction of improper voltage or phase imbalance.

CAUTION

Provide proper line voltage and phase balance. Improper line voltage or excessive phase imbalance can cause severe damage to the unit's electrical components.

A ground lug is provided in the control panel for each power conduit. Size grounding conductor in accordance with Table 250-95 of the National Electrical Code.

In compliance with the National Electrical Code, an electrically isolated 115V circuit is provided in the unit to supply the factory mounted service receptacle outlet and optional unit lights. This circuit is powered by a field connected 15A, 115V power supply . Leads are brought into the RFS and RPS units through a 7/8" knockout in the bottom of the main control panel, near the power wire entry point.

Note: The National Electrical Code requires that this 115V circuit be protected by a ground fault circuit interrupter (GFI)

device (field supplied).

WARNING

Electrical shock hazard. Can cause severe injury or death.

All protective deadfront panels must be reinstalled and secured when power wiring is complete.

Table 5: Recommended 3-Phase Power Wiring*

WIRE

GAUGE

250 1 75 1 2-1/2 255 300 1 75 1 2-1/2 285 350 1 75 1 3 310 400 1 75 1 3 335 500 1 75 1 3 380

250 2 75 2 2-1/2 510 300 2 75 2 2-1/2 570

QTY./

POLE

1 1 75 1 1-1/4 130 1/0 1 75 1 1-1/2 150 2/0 1 75 1 2 175 3/0 1 75 1 2 200 4/0 1 75 1 2 230

3/0 2 75 2 2 400 4/0 2 75 2 2 460

INSULATION

RATING (°C)

NO. OF

CONDUITS

CONDUIT

(TRADE

SIZE, IN.)

FOR MCA

UP TO

(AMPS)

WIRE

GAUGE

350 2 75 2 3 620 400 2 75 2 3 670 500 2 75 2 3 760 250 3 75 3 2-1/2 765 300 3 75 3 2-1/2 855 350 3 75 3 3 930

QTY./

POLE

INSULATION RATING (°C)

NO. OF

CONDUITS

CONDUIT

(TRADE

SIZE, IN.)

FOR MCA

UP TO

(AMPS)

Note:

1. All wire sizes assume separate conduit for each set of parallel conductors.

2. All wire sizes based on NEC Table 310-16 for THW wire (copper). Canadian electrical code wire ampacities may vary.

3. All wire sizes assume no voltage drop for short power leads.

*To provide that disconnects and power blocks mate with power wiring.

Condenser Fan Cycling

FanTrol is provided on all units and is a method of head pressure control which automatically cycles the condenser fans in response to sump water temperature. This feature maintains head pressure and allows the unit to operate down to 45°F ambient.

RDE and RPE units have two independent refrigerant circuits with two to three condenser fans being controlled independently by the sump water temperature.

Condenser Fan Wiring

A standard JCI A99 temperature sensor connects to MCBAI11 to measure the temperature in the sump of the condensing unit.

All condenser fans on each compressor circuit turn on and off using the same outputs as the Compressor Circuit Board that control the fans. Condenser Fan #1 for each circuit turns on and off through BO #5 on the compressor board for that circuit. Condenser Fan #2 for each circuit turns on and off through BO #6 on the compressor board for that circuit. Condenser Fan #3 for each circuit turns on and off through BO #7 on the compressor board for that circuit. If the unit has an optional VFD for condenser fans 11 and 21, the VFD is turned on digitally from the MCB.Keypad Display

Table 6: Evap Condensing Menu Items

Evap Condensing VFD Speed = XXX % - Rounded to the nearest percentage

instead of being truncated Sump Temp=xxx°F Min Fan Speed=25% 0% to99% Min SumpT=80°F 0° to 99°F Max SumpT=90°F 0° to 99°F Stage Time+ 10 Min 0 Min to 99 Min

36 McQuay IM 791-2

Mechanical Installation

Field Control Wiring

RoofPak applied rooftop units are available with several control arrangements which may require low voltage field wiring. Detailed descriptions of various field control wiring options and requirements are included in the “Field Wiring” section of Bulletin No. IM 696, MicroTech II Applied Rooftop Unit Controller. Refer to the unit wiring diagrams for additional installation information.

Wiring must comply with applicable codes and ordinances. and these specifications. Defects caused by incorrect wiring

are not covered by the warranty.

WARNING

Electrical shock hazard. Can cause severe injury or death.

Connect only low voltage NEC Class II circuits to terminal blocks TB2 and TB7. Reinstall and secure all protective deadfront panels when the wiring installation is complete.

Most field control wiring connections are made at terminal block TB2, which is located in the main control panel. Some control options require field wiring connections to terminal block TB7, which is also located in the main control panel.

Refer to Figure 38 and see Control Panel Locations‚ page 12. T wo 7/8" knockouts are provided for wire entry. A 7/8" knockout is also available in the end of the unit base.

Note: If a single conduit containing 24V and 115V wiring is run

above the roofline between the RFS and RCS units, the 24V wiring must be reinstalled as an NEC Class I wiring system.

Figure 38: RDE and RPE Control Wiring Raceway

McQuay IM 791-2 37

Preparing Unit for Operation

WARNING

Moving machinery hazard. Can cause severe injury or death.

Lock out and tag out all power before servicing equipment. More than one disconnect may be required to de-energize unit.

Relief Damper Tie-Down

Economizer sections with a 30" or 40" return fan have a relief damper that is tied down for shipping. Two brackets and two screws must be removed before operation to allow free movement of dampers. Access is from inside the economizer section.

Spring Isolated Fans

WARNING

Moving machinery hazard. Can cause severe injury or death. Before servicing equipment, disconnect power and lock off. More than one disconnect may be required to de-energize unit.

Figure 39: RDT Spring Mount Hold Down Fasteners

Hold-down fasteners

Releasing Spring Mounts

The optional spring-mounted supply and return fans are locked down for shipment. Hold-down fasteners are located at each spring mount. Remove these fasteners before operating the fans. Figure 41 shows a typical spring mount. Note that the 3/8" hold-down bolt securing the fan base to the unit cross channel must be removed.

After removing the hold-down fasteners, rock the fan assembly by hand to check for freedom of movement.

Figure 40: Fan Spring Mount Adjustment

Leveling screw

Spring mount

assembly

Cross

channel

* Grossly out-of-adjustment thrust restraints can affect this dimension.

Recheck after thrust restraints are adjusted.

Jam nut

Fan base

3 /8 " ± 1 /4 " with fan running

Adjusting Spring Mounts

Figure 41: Spring Mount

To adjust spring mount compression, perform the following:

1 Loosen the .625-18 UNF hex nut (Figure 41). 2 Place additional weight on the fan sled frame and use a

lever to slightly compress the spring or raise the sled. This will allow the bolt to turn freely.

3 Place one or two drops of oil on the threads if needed.

Note: The greatest friction that makes adjustment difficult,

comes from the surfaces of the top of the upperrebound plate (Figure 41), both sides of the .615" washer, and the underside of the sled. If friction is occurring at these point, relieve the weight and oil the friction surfaces.

Use a flat blade socket drive bit (1/2" drive handle recommended) and make sure that when adjusting the slotted bolt, that the upper-rebound plate also turns. The slot is located just above the hex nut. This action allows the bolt to push the compression plate (Figure 41) up or down with the lease friction occurring between the .625" washer and the underside of the channel.

Note: If the spring compresses to far, lift the sled before

turning. If the spring does not compress enough, place weight on the sled corner, forcing it down before turning.

Re-adjust the position of the lower-rebound plate so that the sled has at least 3/4" travel and not more than 1.25" of

travel.

CAUTION

Do no use impact tools for field spring mount adjustments as damage to bits or to the bolt slot may occur.

WARNING

Moving machinery hazard. Can cause severe injury or death. Start the fans for the first time according to the Check, Test, and

Start Procedures‚ page 78. If this is not done, equipment

damage, severe personal injury, or death can occur.

38 McQuay IM 791-2

Preparing Unit for Operation

Figure 42: Thrust Restraint Adjustment

WARNING

Follow proper procedures. Severe fan damage can occur otherwise.

The fans must be started for the first time in accordance with the Check, Test, and Start Procedures‚ page 78. If this is not done, personal injury and severe fan damage can occur.

Adjustment of Supply Fan Thrust Restraints

Thrust restraints are provided when housed double-width fans are mounted on springs. After the spring mounts have been adjusted for level operation when the fan is running, the thrust restraints should be checked. With the fan off, the adjustment nuts should be set so the spring is slightly compressed against the angle bolted to the fan housing frame. Refer to Figure 42. When the fan is turned on, the fan will move back to a level position and the thrust restraint springs will compress

J a m N u t " A "

N u t " B "

S p r i n g C l i p

D e t a i l " A "

S e e D e t a i l " A "

W a s h e r

N u t " C "

J a m N u t " A "

T h r u s t R e s t r a i n t A n g l e

F a n H o u s i n g F r

a m e

F a n B u l k h e a d

Thrust Restraint Adjustment (With Fan Off)

1.Loosen jam nuts “A”.

2.Turn nut "C" until spring cup and washer contact thrust restraint angle.

3.Turn nut "B" until spring is compressed by two turns of nut "B".

4.Tighten jam nuts "A".

McQuay IM 791-2 39

Preparing Unit for Operation

Adjustment of Seismic Restraints

Spring mounted supply air and return air fans may be ordered with factory installed seismic restraints. Refer to Figure 43. The system consists of four snubbers, one located next to each spring isolator. These snubbers will allow free movement of the fan assemblies during normal operation because normal operation will not cause fan movements that exceed .25" (6 mm). However, they will restrain the fan assembly and limit movement to .25" (6 mm) in any direction if an abnormal condition were to occur.

The position the fan will assume during normal operation will be determined by actual job site airflow and static pressure. Therefore, for proper operation, the seismic restraints must be field adjusted as part of the normal “Check, Test and Start” procedure. When the fan is operating in a normal manner there should be no contact between the snubber restrainer angle and the snubber neoprene bumper. However, in a “seismic event,” the snubber will limit movement of the spring mounted fan assembly to .25" (6 mm) in any direction, thereby helping to prevent the fan from being tossed about and damaged, or causing damage.

When a seismic restraint is properly adjusted and the fan is operating normally, the neoprene center bumper will be centered within the 2" (51 mm) diameter hole in the restrainer angle, and the restrainer angle will be centered vertically between the flanges of the neoprene center bumper. This results in .25" (6 mm) clearance in all directions. When the fan is turned off the restrainer angle may come to rest on the neoprene center bumper.

The seismic restraint is adjustable in all directions. Vertical slots in the restrainer angle and horizontal slots in the blower base allow the restrainer angle to be adjusted up and down and back and forth. The neoprene center bumper is mounted on a slotted hole allowing its adjustment in and out.

Removing the neoprene center bumper bolt allows removal, disassembly, and replacement of the neoprene components.

Spring Isolated Compressors

Units that have been ordered with optional compressor mounting springs must have the rigid shipping spacers removed before operating the units. Refer to Figure 44.

Before operating the unit, remove and discard the shipping spacers (1) and install the neoprene spacers (2). Remove the top mounting nuts (3). Install one neoprene spacer on each of the four mounting bolts.

Replace the mounting nuts, leaving 1/16" (2mm) space between the mounting nut and the neoprene spacer.

Figure 44: Compressor Mounting Springs

Figure 43: Cross Section of Seismic Restraint

F a n B a s e C h a n n e l

S n u b b e r R e s t r a i n e r A n g l e

A d j u s t U p o r D o w n

o r B a c k a n d F o r t h

S n u b b e r N e o p r e n e

. 2 5 "

S n u b b e r N e o p r e n e

d j u s t I n a n d O u t

B u m b e r

( 6 m m ) G a p

( F a n R u n n i n g )

B u m b e r

40 McQuay IM 791-2

Sequences of Operation

The following sequences of operation are for a typical “C” vintage applied rooftop unit that is equipped with MicroTech II, an economizer, 4 compressor / 8stage cooling, 3 to 1 turn down burner, variable frequency drives (VFD), a return air fan and an external time clock. These sequences describe the ladder wiring diagram logic in detail; refer to Wiring

Diagrams‚ page 47 as you read them. Note that your unit's

sequences of operation may vary from those described here. Refer to the wiring diagrams supplied with the unit for exact information.

For detailed description of operation information relating to the MicroTech II controller's software, refer to the appropriate operation manual (see Table 1, page 3). These manuals describe the various setpoints, parameters, operating states, and control algorithms that affect rooftop unit operation.

Power-up

Sequences of Operation

Fan Operation

When the main control board (MCB) commands the supply and return fans to start, the unit enters the Startup operating state. As a result, a 3-minute timer is set, output MCB-BO3 (line 307) energizes, and relay R26 energizes (line 306).

After the 3-minute timer expires, the unit enters the Recirc operating state. As a result, output MCB-BO1 energizes relay R67 (line 401). This gives a start signal to supply fan drive AFD10 (line 445). Four seconds after MCB-BO1 is energized, output MCB-BO2 energizes relay R68 (line 404). This gives a start signal to return fan drive AFD20 (line 445).

Within 120 seconds after the fans start, the controller expects airflow switch PC7 (line 228) to close and thus energize binary input MCB-BI6. (If MCB-BI6 does not energize, the controller assumes the fans did not start. It then shuts down the unit and generates an alarm.)

When primary power is connected to the unit, 115VAC power is fed through control circuit transformer TI and control circuit fuse FI (line 168) to compressor crankcase heaters HTR-1, HTR-2, HTR-3 and HTR-4 (lines 815, 850, 820 and 855).

When system switch S1 (line 203) is closed, low voltage transformers T2 (line 203), T3 (line 301)and T9 (line 802) are energized, and 115 VAC power is supplied to the following:

• Smoke detectors (lines 265 and 267)

• Economizer actuator ACT3 (line 313)

• M30A to energize the supply fan VFD (line 426)

• M40A to energize the return fan VFD (line 430)

• Heating control panel (line 603)

• Compressor circuit switches CSI and CS2 (lines 805 and

840)

Transformer T2 supplies 24VAC power to terminals 24V & 24C on the main control board MCB (lines 207 and 208). T2 supplies 24VAC power to the following:

• Switch S7 On-Auto-Off (line 217)

• Enthalpy sensor OAE (line 250)

• External time clock contacts (line 215)

• External exhaust fan status contacts (line 257, VAV only)

• Airflow interlock switch PC7 (line 228)

• Dirty filter switches PC5 and PC6 (lines 242 and 247)

• Duct high limit switch DHL (line 260)

• Gas furnace alarm relay R24 (line 225)

• Freezestat switch FS1 (line 231)

• Smoke detectors SDI and SD2 (line 237)

When the field supplied Cool Enable switch is in the “off” position, field wiring terminal 105 is de-energized (line 220). Binary input MCB-BI3 will be de-energized and the cooling will be disabled. When the field supplied Heat Enable switch is in the “off” position, field wiring terminal 106 is deenergized (line 223). Binary input MCB-BI4 will be deenergized and the heating will be disabled. Note: Unit ships with factory installed jumpers between 101 and 105 and between 101 and 106.

During the Recirc operating state, the outside air damper is held closed. The controller does this by energizing output MCB-BO5 (line 318). On VAV units, output MCB-BO12, the VAV box output, is also de-energized (line 309) during the Recirc state.

The supply fan adjustable frequency drive (AFD10) is modulated to maintain the duct static pressure setpoint. When energized, output MCB-BO14 (line 407) drives AFD10 toward increased capacity; MCB-BO13 (line 405) drives it toward decreased capacity. On VAV units or CAV units equipped with return fan capacity control, the adjustable frequency drive (AFD20) is modulated to maintain an acceptable building static pressure (using either VaneTrol logic or direct measurement of building pressure; see the appropriate OM for more information). When energized, output MCB-BO16 (line

409) drives AFD20 toward increased capacity; MCB-BO15 (line 411) drives them toward decreased capacity.

Note: If the inverter bypass switch S4 (lines426 and 430) is in

the bypass position, MMP30 and MMP40 (line 132 and

144) protect the fans from excessive current draw. If either the supply or return fan is drawing excessive current, one of the MMPs triggers an auxiliary contacts (line 426) and open the circuit, causing both fans to stop.

Economizer Operation

When the outdoor air is suitable for free cooling, the switch in enthalpy sensor OAE is in position “3” (line 252) energizing binary input MCB-BI11. When MCB-BI11 is energized, the economizer is enabled. (Note: If selected from the keypad, the enthalpy decision can be made based on outdoor temperature. In that condition, if the outdoor air temperature is less than or equal to the changeover setpoint, the economizer is enabled.) If cooling is required, the economizer dampers (ACT3) are modulated to maintain the discharge air temperature setpoint. When energized, output MCB-BO6 drives the outdoor air dampers towards the open position, and MCB-BO5 towards the closed (line 318). If the outdoor air dampers are wide open and more cooling is required, the dampers will hold their

McQuay IM 791-2 41

Sequences of Operation

positions and mechanical cooling will be activated (see below).

When the outdoor air is not suitable for free cooling, the switch in enthalpy sensor OAE is in position “1”, deenergizing binary input MCB-BI11 (Alternatively, the outdoor air temperature is above the changeover setpoint plus the economizer changeover differential). When the economizer is disabled, the dampers are held at their minimum position.

General Cooling Control

A unit with evaporative condensors cannot operate in a cooling state below 40ºF. If the OAT Compressor Loackout Temperature on units with evaporative condensing is lowered below 40ºF, it will immediately be set back to 40ºF

Condenser fan #1 on each circuit is turned on and off via ModBus communications with a single VFD. These two fans always operate at the same speed.

Condenser fan #1 and #3 on each compressor circuit are turned on and off using the two outputs on the main control board that are used for standard condenserfans. Relays are driven by each of these outputs so that fans associated with a circuit that is not operating will not be turned on.

Sump Pump Control

The pump output is turned on whenever the unit is in the Cooling state and the Sump Pump Fail condition described below is false. The Sump Pump is turned on before any compressor or condenser fan is turned on.

A Sump Pump Fail condition is set to True if the Sump Pump status is Open after the Sump Pump Output has been turned on for more than the Sump Pump Delay time (Default equals 30 seconds). The Sump Pump Fail condition remains true for one cooling stage time. The Sump Pump is turned off and the maximum Cooling Stage is set to zero when the Sump Pump Fail condition is true. A manual clear Sump Pump Fail Problem that disables cooling becomes active if Cooling has been limited to Stage Zero due to Sump Pump Fail conditions three times between 2:00 AM of one dav and 2:00 AM of the next day.

If the non-chemical water treatment option is provided, the sump pump is run every three days to reduce scaling. The pump output is turned on for one hour if all of the following are true:

• The sump pump has been off for more than 72 hours, but

less than 120 hours,

• The outside air temperature is greater than 35°F.

Configuration Options

There are two configurations of Evaporative Condensing units. One has two condenser fans per refrigerant circuit. The other has three condenser fans per circuit. In addition, the first fan on each circuit can either have a VFD or not. Configuration string position #6 is set based on the configuration of the unit.

See IM696-2, OM137-3 or OM138-3 for definitions of values used in this position.

Sequence of Operation

A condenser fan is allowed to operate only when one or more compressors on the corresponding circuit are operating. On condensers with no VFD's, if circuit #1 is lead, CCB1-BO5 energizes condenser fan contactor M11. If there is a VFD, the digital bus communicates a start signal to the VFD to start both M11 and M21. SWT sensor wired into MCB-AI11 looks at the sump water temperature and stages additional fans as necessary. CCB1-BO6 energizes M12. CCB2-B06 energizes M22. CCB1-BO7 energizes M13. CCB2-B07 energizes M23. Refer to OM138-2 or OM138-2 for a more complete sequence.

Also refer to Figure 45, page 43 (with VFD) and Figure 46,

page 44 (without VFD) for condenser fan and spray pump

sequence of operation concept schematics. For a typical detailed schematic, see Typ ical Cond ensing Unit Control -

MicroTech II - 4 Compressor‚ page 60.

Speedtrol

After the pump and compressors are turned on, the sump temperature rises to 80°F . At that point the VFD fans go to minimal speed (20 Hz). Under low ambient conditions, the VFD fans may not be running or cycle on and off.

As the sump temperature increases to 90°F, the VFD condenser fans (2) are ramped up to 100% (60 Hz) at a rate that is proportional to the temperature rise above 80°F (i.e. 4 Hz change per °F).

Above 90°F, the next fan of a lead-lag fan staging is turned on and the VFD is slowed down to the minimum speed and then ramped up to maintain the sump temperature between 80-90°F until all fans are turned on. Under extreme hot or humid conditions, the sump temperatures may rise to 105-110°F with all fans running.

When the sump temperature falls below 80°F and the VFD is at minimal speed (20 Hz), the lead-lag fans are staged off and the VFD is ramped up to maintain the 80-90°F sump temperatures.

Emergency Sump Drain Sequences

There are two instances where the unit controls will open the drain solenoid and drain the sump. At that time, virtually the entire spray system will drain via gravity (an exception is a small trap that keeps the optional conductivity sensor immersed).

If sump water temperature drops below 35°F, the controls assume the optional sump heater has failed or was not ordered, freezing conditions exist, and the water is drained.

If the optional, non-chemical water treatment system is ordered and the spray system has not operated for five days, then the controls assume that organic growth has begun in the spray system, so the water is drained.

The McQuay spray system only holds about 150 gallons of water, so the water costs associated with draining the sump is

42 McQuay IM 791-2

Sequences of Operation

negligible. If the non-chemical water treatment option is utilized, then no chemicals are lost in the draining process.

The entire spray system automatically refills itself when a call for mechanical cooling occurs and ambient temperature is not below 40°F.

Figure 45: Concept Schematic - Evaporative Condensing Control With VFD - 3 Fans Per Circuit

24VAC

115VAC

MicroTech II

Control

Mod-DCU

(MCB)

AI 11

Sump Temp

BO7

Pump

Ctcr Aux

BI12

Pump Relay

The pump must turn on

before compressor and

condenser fans operate

BO6

1312

M12

Comm

Note: M12, M13,

M22 and M23 are

condenser fan

contactors

BI12

Comp

Board # 1

(CCB1)

Comp

Board # 2

VFD

BO7

BO6

BO7

Low Water

Switch

1516

1312

1516

Pump Relay

M13

M22

M23

Pump

Ctcr

Pump

Contactor

The pump can’t operate with

insufficient water.

Controls the speed of 2 fans

McQuay IM 791-2 43

Sequences of Operation

Figure 46: Concept Schematic - Evaporative Condensing Control Without VFD - 3 Fans Per Circuit

MicroTech II

Control

24VAC

Mod-DCU

AI 11

Sump Temp

Comm

BO7

Pump

Ctcr Aux

BI12

24VAC

Pump Relay

Comp

Board # 1

(CCB1)

115VAC

The pump must turn on before compressor and

condenser fans operate

BO5

BO6

BO7

119

1312

1516

M11

M12

M13

Note: M12, M13,

M22 and M23 are

condenser fan

contactors

BI12

Comp

Board # 2

(CCB2)

BO5

BO6

BO7

Low Water

Switch

119

1312

1516

Pump Relay

M21

M22

M23

Pump

Ctcr

Pump

Contactor

The pump can’t operate with

insufficient water.

44 McQuay IM 791-2

Mechanical Cooling Operation

4-Compressor/3 Stage Unit

Refer to page 60 as you read this sequence of operation. In this configuration there are 4 equally sized compressors and two cooling circuits. In the following description, compressor #1 is lead. However, if Auto Lead/Lag Staging is selected on the keypad, the lead compressor will be #1 or #2, depending on run hours.

When the unit disconnect is closed, 115VAC power is supplied directly from control transformer T1 to the compressor crankcase heaters, HTR-1, 2, 3 & 4 (lines 815, 850, 819, 855) and motor protectors MP1, 2, 3 & 4 (lines 816, 851, 820, 856). This same 115 VAC source also goes through:

1 System switch, S1 (line 203) 2 The optional phase voltage monitors, PVM1

(line 203)

3 The optional ground fault relays, GFR

(line 203)

4 Compressor control switches, CS1 & 2 (lines 805, 840) 5 Transformer T9 is also powered

Compressor control switches, CS1 & 2 also provide 24 VAC from transformer T9 to compressor control boards CCB1 and CCB2 (lines 805, 840) as well as the following cooling circuit binary inputs:

1 Frost protect FP1 to CCB1-B18 (line 810) - Optional when

no hot gas bypass is ordered on the unit

2 Frost protect FP2 to CCB2-BI8 (line 846) - Optional when

no hot gas bypass is ordered on the unit

3 HP relay R1 to CCB1-BI7 (lines 825) 4 HP relay R2 to CCB2-BI7 (lines 860) 5 Compressor contactor status M1-AUX2 to CCB1-BI9

(line 807)

6 Compressor contactor status M2-AUX2 to CCB2-BI9

(line 843)

7 Compressor contactor status M3-AUX2 to CCB1-BI10

(line 808)

8 Compressor contactor status M4-AUX2 to CCB2-BI10

(line 844)

9 Circuit pump down switch PS1 to CCB1-BI11 (line 813) 10 Circuit pump down switch PS2 to CCB2-BI11 (line 847) 11 Cool enable from MCB-B07 to CCB1-BI12 and CCB2-

BI12 (lines 813, 848)

When manual pumpdown switches PS1, PS2, and PS3 are closed, all four compressors are fully enabled and ready to start if commanded to by the MicroTech II control system.

Sequences of Operation

Cross Circuit Loading

If cooling is enabled (MCB-BI3 is energized) and mechanical cooling is required, the MCB will energize cool enable output MCB-BO7 (line 813) to binary inputs CCB1-BI12 (line 813) and CCB2-BI12 (line 848). The MCB will also send a digital communications signal to CCB1 & 2 to enable cooling. CCB1BO4 output will energize and open liquid line solenoid valve SV1 (line 831), allowing refrigerant to flow into the evaporator coil. As the refrigerant evaporates, the suction pressure increases until low pressure switch LP1 closes (line

815) as a binary input to CCB1-BI6. When CCB1 senses that LP1 has closed, CCB1-BO1 energizes contactor M1 (line 816) to start compressor #1. CCB1-B03 will energize to unload compressor #1 (line (828). This is stage 1.

If more cooling is required, CCB2-BO4 will energize and open liquid line solenoid valve SV2 (line 866), allowing refrigerant to flow into the evaporator coil. As the refrigerant evaporates, the suction pressure increases until low pressure switch LP2 closes (line 850) as a binary input to CCB2-BI6. When CCB2 senses that LP2 has closed, CCB2-BO1 energizes contactor M2 (line 852) to start compressor #2. CCB2-B03 will energize to unload compressor #2 (line 864). This is stage 2.

If more cooling is required, CCB1-B03 will de-energize to load compressor#1 (line 828). This is Stage 3.

Stage 4: CCB2-B03 de-energizes to load compressor #2 (line 864).

Stage 5: CCB1-B02 energizes to start compressor #3 (line 821) and CCB1-B03 energizes to unload compressor #1 (line 828).

Stage 6: CB2-B02 energizes to start compressor 4 (line 857) and CCB2-B03 energizes to unload compressor #2 (line 864).

Stage 7: CCB1-B03 de-energizes to load compressor #1. Stage 8: CCB2-B03 de-energizes to load compressor #2. When the cooling demand is satisfied, MCB works through

CCB1 & 2 to stage down the compressors. If Auto Lead/Lag Staging is selected, the compressor with the most hours will stage off first and so on. When both circuits are running with only one compressor each (stage 2) and less cooling is required, if circuit #2 is lag, CCB2-BO4 de-energizes to close liquid line solenoid valve SV2 (line 866). As a result, compressor #2 pumps down refrigeration circuit #2 until the suction pressure drops low enough to open low pressure control LP2 (line 850). When LP2 opens, CCB2-BO1, BO5, (BO6 and BO7) will de-energize to shut down compressor #2 and its associated condenser fan(s).

When mechanical cooling is no longer necessary, CCB1-BO4 de-energizes to close liquid line solenoid valve SV1 (line 831). As a result, compressor #1 pumps down refrigeration circuit #1 until the suction pressure drops low enough to open low pressure control LP1 (line 815). When LP1 opens, CCB1BO1, BO5, (BO6 and BO7) will de-energize to shut down compressor #1 and its associated condenser fan(s).

McQuay IM 791-2 45

Sequences of Operation

Lead Circuit Loading

The loading and unloading process is similar except that both compressors in the lead cooling circuit will energize before energizing any compressors in lag circuit.

Compressor Safeties

If a compressor motor protector or oil pressure safety trips, it will immediately disable its associated compressor contactor M1, 2, 3 or 4 (lines 816, 852, 821 and 857), The appropriate CCB*-B0* will de-energize.

If high pressure switch HP1 or HP3 trips (line 827 and 822), compressors #1 and #3 will be disabled and relay R1 will signal CCB1 of the event. (line 825). CCB1 will then deenergize CCB1-BO1 and BO2 (lines 816 & 821) to keep compressors #1 and #3 locked out. If high pressure switch HP2 or HP4 trips (line 862 and 858), compressors #2 and #4 will be disabled and relay R2 will signal CCB2 of the event. (line

860). CCB2 will then de-energize CCB2-BO1 and BO2 (lines 852 & 857) to keep compressors #2 and #4 locked out.

If frost protect switch FP1 trips (line 810), CCB1-BO4 will deenergize (lines 830) to close SV1 and pump down circuit #1. If frost protect switch FP2 trips (line 846), CCB2-BO4 will deenergize (lines 866) to close SV2 and pump down circuit #2. For both of these alarms, the circuit will remain off for at least one cooling stage timer interval. If cooling is still needed, the cooling will try to restart. The cooling will reset up to three times in a 24 hour period (between 2:00 AM and 2:00 AM). After the third trip, the alarm will remain until manually cleared at the keypad or over the network.

Heating

Gas Furnace, Modulating Burner (3 to 1 turn down)

Refer to page 64 as you read this sequence of operation. Note that the gas furnace wiring diagrams supplied with the units include a detailed sequence of operation. Refer to the wiring diagram supplied with the unit for exact wiring and sequence of operation information.

When system switch S1 is closed, 115 VAC power is supplied to the furnace control circuit. If burner switch S3 and safeties HL22, HL23 are closed, terminal 5 (line 609) on the flame safeguard control (FSG) will be energized as will the modulating gas valve VM1. If heating is enabled (MCB-BI4 is energized (line 223) and heating is required, the MCB-BO11 will energize R20 (line 413). The normally open R20 contacts (line 603) close, and if manual burner switch S3 and high limit switches HL22, HL23, FLC (fan limit control), LP5, and HP5 are closed, terminal 6 (line 618) on the flame safeguard control (FSG) will be energized. FSG will energize terminal 4 to start the blower motor (BM) through contactor M29 (line 609). If the blower is operational, air switch AS (line 621) will close

and make FSG terminal 6 to 7. After a 90-second prepurge period, FSG terminals 8 (line 613) and 10 (line 630) are energized. As a result, ignition transformer IT and pilot gas valve GVI are energized. The pilot flame will ignite and be detected by FSG through flame rod FD (line 612). Upon detection of pilot flame after the 10 second trial for ignition period, the FSG will de-energize terminal 10 and energize terminal 9 to energize main gas valves GV2 and GV3 (lines 617, 619) and low fire start relay R23 (line 624). The R23 contacts (lines 632 and 633) allow the MCB to modulate gas valve actuator VM1 as required to satisfy the heating demand.

Whenever the burner is operating, its firing rate will be determined by the position of gas valve actuator VM1. This actuator modulates the butterfly gas valve and combustion air damper (lines 690 and 692), thus varying the furnace firing rate between 33% and 100% of full capacity. When the MCBBO10 energizes (line 634), VM1 modulates toward open and the firing rate increases. When MCB-BO9 energizes (line

644), VM1 modulates toward closed and the firing rate decreases. When both MCB-BO10 and MCB-BO9 are open, VM1 holds its position and the firing rate remains constant.

When heating is no longer necessary, MCB-BO11 opens, deenergizing relay R20 and opening its contacts in line 603. As a result, the flame safeguard control is de-energized, all gas valves close, the combustion air blower motor stops, and gas valve actuator VM1 closes. If the furnace is warm enough to close it, the FLC fan controls switch (line 633) will override supply fan start/stop output MCB-BO1 through R67 (line 607) and keep the supply fan running until the furnace cools down (this might happen during night setback operation).

If the furnace overheats, the FLC high limit control (line 603) will cycle the burner, preventing the furnace temperature from exceeding the limit control's set point. When the furnace is cycled off, low fire start relay R23 de-energizes. The normally closed R23 contacts (line 633) cause VM1 to drive to its minimum position, overriding MicroTech II control of VM1 via MCB-BO10 and MCB-BO9. Because relay R23 is deenergized whenever GV2 is de-energized, the burner will always start at low fire.

Flame Control Lockout

If the pilot flame does not ignite or the flame safeguard fails to detect its flame within 10 seconds, the flame safeguard control will enter the “lockout” state. FSG terminals 4, 8, 9, and 10 will be de-energized and the burner will be shut down. FSG terminal 3 will energize relay R24 (line 225). The R24 contacts (line 244) signal the controller that the problem exists by energizing the input to MCB-BI5. If a lockout occurs, the flame safeguard control must be manually reset.

46 McQuay IM 791-2

Wiring Diagrams

Legend

General Notes

1. Field wiring

Wiring Diagrams

ID Description Standard location

C11 Capacitors, Speedtrol, circuit #1Condenser bulkhead

C20 Power factor capacitors,

return fan

C21 Capacitors, Speedtrol, circuit #2Condenser bulkhead

Return section

2. Factory wiring

3. Shielded wire/cable

4. Main control box terminals

5. Auxilliary box

6. Field terminals

7. Plug connector

8. Wire/harness number

9. Wire nut/ID

ID Description Standard location

ACT3, 4 Actuator motor, economizer Economizer section ACT5 Actuator motor, discharge

ACT6 Actuator motor, return air

ACT7 Actuator motor , heat face/

ACT8 Actuator motor, cool face/

ACT10, 11Actuator motor, exhaust

ACT12 Actuator motor, enthalpy

AFD10 Adjustable frequency drive,

AFD11 Adjustable frequency drive,

AFD20 Adjustable frequency drive,

AFD60 Adjust. freq. drive, energy

AS Airflow switch, burner blower Gas heat box BM Burner blower motor Heat section, gas C1–8 Power factor capacitors,

C10 Power factor capacitors,

200/ H200

WN7

isolation damper

bypass

Bypass

dampers

wheel bypass damper

supply fan

evap cond. fans

return/exhaust fan

recovery wheel(s)

compressors

supply fan

terminals

Discharge section

Return section

Coil section, heat

Coil section, cool

Return section

Energy recovery section

AFD/supply fan section

Main/RCE control box

AFD/ret. ex. fan section

Energy recovery section

Condenser section

Supply Fan section

CB10 Circuit breaker, supply fan Main control box CB1 1 Circuit breaker, evaporative

condenser fan(s)

CB20 Circuit breaker, return/

exhaust fan

CB60 Circuit breaker, energy

recovery wheel

CCB1, 2 Compressor control boards,

refrig. circuits

CPC Circuit board, main, micro

controller

CPR Circuit board, expansion,

micro controller

CS1, 2 Control switches, refrig.

circuits

DAT Discharge air temperature

sensor DFLH Design flow lefthand sensor Return section DFRH Design flow righthand sensor Return section DHL Duct hi-limit Main control box DS1 Disconnect, total unit or cond/

heat DS2 Disconnect, SAF/RAF/

controls DS3 Disconnect, electric heat Electric heat box DS4 Disconnect, condenser (RCS

Only) EAT Exhaust air tempe rature

sensor EFT Entering fan air temperature

sensor EHB1 Staged electric heat board Main control box ERB1 Energy recovery board Main control box ERM1 Energy recovery wheel motor #1Energy recovery section

ERM2 Energy recovery wheel motor #2Energy recovery section

F1A, B Fuse, control circuit

transformer (T1), primary F1C Fuse, control circuit

transformer (T1), secondary F2 Fuse, control circuit

transformer (T2), primary F3 Fuse, burner blower motor Main control box FB11, 12 Fuseblock, Speedtrol Main/cond. control box FB31–40 Fuseblock, electric heat (top

bank) FB41–50 Fuseblock, electric heat (bot.

bank) FB65 Fuseblock, evap. cond. sump

heater FD Flame detector Heat section, gas FLC Fan limit control Heat section, gas FP1, 2 Frost protection, refrig. circuits Coil section, cool FS1, 2 Freezestat control Coil section, heat/cool FSG Flame safeguard Gas heat box

Main/cond. control box

Main control box

Main/cond. control box

Discharge section

Main control box

RCS control box

Energy recovery section

Supply fan section

Main control box

Electric heat box

Main/cond. control box

McQuay IM 791-2 47

Wiring Diagrams

ID Description Standard location

GCB1 Generic condenser board,

refrig. circ. GFR1, 2 Ground fault relay Main control box GFS1, 2 Ground fault sensor Main control box GFR4 Ground fault relay, condenser Condenser control box GFS4 Ground fault sensor,

condenser GRD Ground All control boxes GV1 Gas valve, pilot Heat section, gas GV2 Gas valve, main/safety Heat section, gas GV3 Gas valve, redundant/safety Heat section, gas GV4–8 Gas valve, main, hi turn down Heat section, gas HL1–10 Hi-limits, pwr, elec he ater s

(top bank) HL11 –20 Hi-limits, pwr, elec heaters

(bot. bank) HL22 Hi-limits, gas heat (pre-filters) Supply fan section HL23 Hi-limits, gas heat (final filters) Final filter section HL31–40 Hi-limits, ctl. elec heaters (top

bank) HL41–50 Hi-limits, ctl. elec heaters (bot.

bank) HP1–4 Hi-pressure controls, refrig On compressors HP5 Hi-pressure controls, gas Heat section, gas HS1 Heat switch, electric heat

shutdown HS3 Heat switch, electric heat

deadfront interlock HTR1–6 Crankcase heaters On compressors HTR65 Heater, sump Evap. condenser section HTR66 Heater, vestibule Evap. condenser

HUM1 Humidstat sensor Energy recovery section IT Ignition transformer Gas heat box LAT Leaving air temperature

sensor LP1, 2 Low-pressure controls,

refrigeration LP5 Low-pressure control, gas Heat section, gas LR10 Line Reactor, supply fan Inverter bypass box LR20 Line reactor, return/exhaust

fan LS1, 2 Limit switch, low fire, high fire Gas heat box LT10– 23 Light, cabinet sections Supply fan section M1–8 Contactor, compressor Main/cond. control box M10 Contactor, supply fan Main control box M11–18 Contactor, condenser fans,

circuit #1 M20 Contactor, return fan Main control box M21–28 Contactor, Condenser fans,

circuit #2 M29 Contactor, burner moto r Gas heat box M30 Contactor, reversing, invertor

bypass, supply fan M31–39 Contactor, electric heat (top

bank) M40 Contactor, reversing, Invertor

Bypass, Return Fan M41–50 Contactor, electric heat (bot.

bank) M60 Contactor, energy recover y

wheel

Main control box

Condenser control box

Heat section, electric

Main control box

Electric heat box

vestibule

Energy recovery section

On compressors

Inv. bypass/main cont. box

Main/cond. control box

Inverter bypass box

Electric heat box

Inverter bypass box

Electric heat box

Main control box

ID Description Standard location

M64 Contactor, sump pump Main/cond. control box M65 Contactor, sump heater Main/cond. control box MCB Microprocessor circuit board Main control box MJ Mechanical Jumper All control boxes MMP1–8 Manual motor protector,

compressors

MMP10 Manual motor protector,

supply fan

MMP11–18Manual motor protector , cond.

fans, ckt#1

MMP20 Manual motor protector, return

fan

MMP21–28Manual motor protector , cond.

fans, ckt#2

MMP30 Manual motor protector, invrtr.

bypass, sup. fan

MMP40 Manual motor protector, invrtr.

bypass, ret. fan MMP51, 52, 53 MMP60 Manual motor protector,

MMP64 Manual motor protector, sump

MP1–6 Motor protector, compr.#1-6 On compressors OAE Outside air enthalpy sensor Economizer section OAT Outside air temperature

OP1–4 Oil pressure controls,

PB1, 2 Power block, power

PB3 Power block, power

PB4 Power block, power

PB9, 10 Power block, supply fan Junction box, split unit PB11, 12 Power block, power

PB19, 20 Power block, return/exhaust

PC5 Pressure control, clogged filter Pre filter section PC6 Pressure control, clogged final

PC7 Pressure control, proof airflow Supply fan section PC8 Pressure control, minimum

PC12, 22 Pressure control, Fantrol Condenser section PM1 Phone modem Main control box PS1, 2 Pumpdown switches, refrig

PS3 Pumpdown switch, RFS only Main control box PVM1, 2 Phase voltage monitor Main control box PVM4 Phase voltage monitor,

R1, 2 Relay, hi pressure reset Main/cond. control box R3, 4 Relay, hi pressure delay Main/cond. control box R5–8 Relay, safety, cool fail Main/cond. control box R9, 10 Relay, compresso r lockou t Main/cond. control box R11, 12 Relay, Speedtrol fan cycling Main/cond. control box R20 Relay, Heat, gas/ steam/ hot

Manual motor protector,

exhaust fan(s)

energy recovery wheel

pump

sensor

compr.#1-4

distribution

distribution, electric heat

distribution, condenser

distribution

fan

filter

airflow

circuits

condenser

water

Main/cond. control box

Main control box

Main/cond. control box

Main control box

Main/cond. control box

Inverter bypass box

Prop exhaust box

Main control box

Main/RCE control box

Economizer section

Condenser section

Main control box

Electric heat box

Condenser control box

Main control box

Junction box, split unit

Final filter section

Coil section, cool

Main/cond. control box

Condenser control box

Gas heat/main cont. box

48 McQuay IM 791-2

Wiring Diagrams

ID Description Standard location

R21, 22 Relay, heat, gas (hi-turn

down) R23 Relay, heat, gas & electric Gas/electric heat box R24 Relay, heat alarm, gas Main control box R25 Relay, heat, gas, start supply

fan inverter R26 Relay, isol/exh. dampers,

open/close R28 Relay, isolation damper,

safety R29 Relay, remote fire alarm Main control box R30 Relay, cool valve with face

bypass R45 Relay, UV lights Main control box R46, 47 Relay, supply fan inverter,

incr/decr R48, 49 Relay, return fan inverter, incr/

decr R56 Relay, heater, water pipe Main/RCE control box R58,59 Relay, heat wheel inverter,

incr/decr R60 Relay , energy recovery wheel,

enable R61 Relay, smoke detector,

discharge air R62, 63, 65Relay, use o n specials Main control box

R64 Relay, sump pump Main/RCE control box R66 Relay, smoke detector, return

air R67 Relay, supply fan, enable Main control box R68 Relay, return fan, enable Main cont rol box R69 Relay, Inv. bypass VAV box

interlock R70–79 Relay, use on specia ls Main control box RAE Retur n air enthalpy sensor Return section RAT Return air temperature sensor Return section REC1 Receptacle, main box Main control box REC2 Receptacle, condenser box Condenser control box REC3 Receptacle, field power, 115V Discharge bulkhead REC10–23Receptacle, cabinet sections Cabinet sections

S1 Switch, system on/off Main control box S2 Switch, system on/off,

condenser unit S3 Switch, furnace on/off Gas heat box S4 Switch, inverter bypass, on/ off Main control box S7 Switch, local on/auto/off to

controller S10–23 Switches, cabinet section

lights S40–45 Switches, door interlock, UV

lights SC11 Speed control, circuit #1 Condenser bulkhead SC21 Speed control, circuit #2 Condenser bulkhead SD1 Smoke detector, supply Discharge section SD2 Smoke detector, return Return section SPS1, 2 Static pressure sensors, duct/

building SR1-3 Sequencing relays, electric

heat SV1, 2 Solenoid valves, liquid Condenser section

Gas heat box

Main control box

Condenser control box

Main control box

Cabinet sections

Main control box

Electric heat box

ID Description Standard location

SV5, 6 Solenoid valves, hot gas Condenser section SV61, 62 Solenoid valves, sump, fill Main/RCE control box SV63 Solenoid valves, su mp, drain Main/RCE control box SWT Sump water temperature

T1 Transformer, main control

T2 Transformer, control input

T3 Transformer, control output

T4 Transformer, exh. damper

T5 Transformer, electric heat Electric heat box T6 Transformer, dew point

T9 Transformer , refrig. circuit 24V Main control box T11 Transformer, speedtrol (line/

TB1 Terminal block, internal Main control box TB2 Terminal block, field Main control box TB3 Terminal blocks, factory Main control box TB4 Terminal block, RFS, field Main control box TB5 Terminal block, RCS, field Condenser control box TB6 Terminal block, RCS, factory Condenser control box TB7 Terminal block, 115V

TB8 Terminal block, 115V conv.

TB11 Terminal block, heat Heat control box TB23 Terminal block, oil pressure

TB25, 26, 27, 28 TC12, 13, 14 TC56 Temperature control, water

TC66 T emperature con trol, vestibule

TD1, 2 Time delay, compressor

TD3, 4 Time delay, hi-pressure Main/cond. control box TD5–8 Time dela y, part winding,

TD10 Time delay, hi turn down

TD11, 12 Time delay, low ambient Main/cond. control box TR1, 2 Transducer, pressure Main control box U1, 2 Unloaders, compressors On compressors UV Ultra-violet light(s) Coil/discha rge section VM1 Valve motor #1, heating Gas heat box/ heat

VM5 Valve motor #5, cooling Coil section, cool VV1 Vent valve, gas heat Heat Section, Gas WL63 Water level, sump, fill Evap. condenser section WL64 Water level, sump, low water Evap. condenser section ZNT1 Zone temp. sensor, setback Field installed

sensor

(line/1 15 V (ac)

(1 15/ 24 V (ac)

actuator (115/12 V (dc)

controller (115/24 V (ac)

240 V (ac)

convenience outlet, field

outlet, RCS, field

box, RPE/RCE only Terminal block, split unit junction box Temperature controls, Fantrol Condenser section

pipe heater

exhaust fan

lockout

compr #1 - 4

burner

Evap. condenser section

Main control box

Condenser section

Main control box

Condenser control box

Evap. condenser vestibule Junction box, split unit

Evap. condenser vestibule Evap. condenser vestibule Main/cond. control box

Main control box

Gas heat box

section

McQuay IM 791-2 49

Wiring Diagrams

Typical Control Schematic: Discharge Air Control (DAC)

NOTE - BACnet IP shown.

See IM 696 pages 5-7 for

more details.

50 McQuay IM 791-2

Wiring Diagrams

McQuay IM 791-2 51

Wiring Diagrams

Typical Control Schematic: Zone or Space Comfort Control (SCC)

NOTE - BACnet IP shown.

See IM 696 pages 5-7 for

more details.

52 McQuay IM 791-2

Wiring Diagrams

McQuay IM 791-2 53

Wiring Diagrams

Typical Output Schematic: Actuator Control

54 McQuay IM 791-2

Typical Schematic: Condenser Fan, Anti-Corrosion Electric Heaters

Wiring Diagrams

McQuay IM 791-2 55

Wiring Diagrams

Typical Output Schematic: VFD Control (SAF/RAF)

631603

/1.68/2.68 /3.11 /3.11

427 445

T1_NT2_115VAC

432 445

168C

445

137

PL7

+PP

309

445

133

149

145

PL8

+PP

303B

102

R67

R25

401A

jprs

24V SRC

1NO1

BO1

207

MCB

604

SUPPLY FAN

102

H1C

R46_47

H1DN

405A

jprs

24V SRC

BO13

RETURN FAN

MCB

447

H1UP

407A

jprs

24V SRC

14NO14

13NO13

BO14

207

SAF DECR

MCB

R68

404A

jprs

24V SRC

2NO2

BO2

207

MCB

207

SAF INCR

R48_49

jprs

BO15

MCB

H1DN

409A

24V SRC

H1C

447

+PP

PL18

H1UP

C3C1

R20

+GB

H413-7 H413-6

+PP

PL18

413A

411A

jprs

24V SRC

16NO16

15NO15

BO16

207

RAF DECR

MCB

207

RAF INCR

BO11

MCB

11NO11

207

HEAT ENABLE

+BB

M30I

PL7

+PP

INVERTER

H425-2

A2A1

H425-12

425A

SUPPLY

+PP

H429-11

A2A1

+BB

M30B

R69

H427-9

PL7

+PP

427B

R67

427A

1NO

1NC

BYPASS

AIR

426B

PL8

A2A1

RETURN

A2A1

+BB

M40B

H431-7

PL8

+PP

404

R68

431A 431B

2ND

2NC

BYPASS

AIR

+BB

M40I

H429-10

PL8

+PP

401

429A

INVERTER

SIG_1/6.01

(Schematic continues on next page.)

H426-4H426-6H426-3

+BB

MMP40

H426-1

PL8

424

+BB

425

+PP

426A

PL7

+PP

MMP30

PL7

+PP

426

12(32)11(31) 12(32)11(31)

133 145

427

428

429

430

431

432

433

T3_24V T3_COM

400

45 42

TB2 TB2

SOURCE 9-16

WIRED INTERNAL

TO MOTHERBOARD

402

MCB

403

9-16

SRC

207

203B

404

405

406

407

408

409

410

411

412

413

414

415

416

417

418

419

420

421

422

423

303A

401

56 McQuay IM 791-2

Typical Output Schematic: VFD Control Continued (SAF/RAF)

+PP

+NB

AFD20

149

RAF

264

ABB401

PL8

H443-2

1216

1113

+PP PL8

H443-5

+PP

R66

R68

PL8

445C 445D

443H

H2DNH2VH2UP

DECRINCR

443G

404 241430

409

R48_49

Wiring Diagrams

H443C

+PP PL8

H443-12

+PP PL7

H443-1

137

261

(Schematic continues on previous page.)

1216

SAF

+NB

AFD10

ABB401

1113

+PP PL7

H443-4

H443A

+BB

M40I

R61M30I

R67

+PP

H443-15

1413

443E

443D

351413

445A 445B

PL7

H443-14

H2DNH2VH2UP

DECRINCR

443C

401 239425

405

R46_47

+PP

435

436

437

438

439

440

441

H443-7

442

PL7

443

444

443A

445

446

447

448

449

450

McQuay IM 791-2 57

Wiring Diagrams

Typical Power Circuit Wiring - 4 Compressor - VFD

58 McQuay IM 791-2

Wiring Diagrams

McQuay IM 791-2 59

Wiring Diagrams

Typical Condensing Unit Control - MicroTech II - 4 Compressor

60 McQuay IM 791-2

Wiring Diagrams

McQuay IM 791-2 61

Wiring Diagrams

Typical CV Fan Control (SAF and RAF) and Light/Receptacle Power

/1.68

T1_N

/3.11

T3_COM

R67

R68

A2A1

M10

A2A1

M20

jprs

401A

24V SRC

BO1

MCB

TB2

207

11NO

R67

426C426B426A

401

R68

431A

404

404A

24V SRC

BO2

MCB

207

22NO

RETURN FAN

jprs

SUPPLY FAN

12(32)

MMP20

11(31)

TB2

SOURCE 9-16

WIRED INTERNAL

TO MOTHERBOARD

MCB

SRC 9-16

207

12(32)

/3.11

T3_24V

MMP10

11(31)

115VAC_GF/1

62 McQuay IM 791-2

Wiring Diagrams

McQuay IM 791-2 63

Wiring Diagrams

Typical Super Mod Gas Furnace Control (1000 MBh)

632615

402

H604-5

TB11

+PP

PL19

T1_N

/1.68

168C

R25

+MB

604B

+PP

PL19

H604-3

TB11

RED_G602-L1

604A

FLC

RED_G603-L3

413

RED_G602-L1

R20

TB11

RED_G602-L2

607A

602A

TB11

H603-4

+PP

PL19

H602-2

603A 603B 603C

+PP

PL19

PL16

+PP

H603-2

426B

SIG_1/4.28

HL22

225

627

TB11

R22

20202020202020

R24

+MB

WHITE

WHTBLK

+PP

PL19

H610-1

BLKBLK

GV1A

BLACK

GV1B

19191919191919

WHITE

WHTBLK

GV4A

GV4B

BLACK

SEE THE PIPING SCHEMATIC BELOW

REQUIRED FOR YOUR BURNER SIZE

FOR THE NUMBER OF MAIN GAS VALVES

21212121212121

C2C1

R23

115V

TB11

RED_G609-L WHT_G609-R

RED_G613-L

NOCOM

LS1

RED_G617-L WHT_G617-R

625

R23

TB11

BLACK BLACK

TB11

610A 610B

613A 613B

611A

4K1

617A

2K2

621C

107

5K12K11K1

3K1

FSG

6K1

FIER

FSG

AMPLI

FLAME

(FLAME SAFEGUARD)

(PLUG-IN TYPE

CONTROLLER)

621B

ASLS2

COM

621A

COM

TB11

MICROCOMPUTER

FSG-F

FSG-G

(FLAME ROD)

(L1)

632628

C2C1

R21

IGNITION TRANSFORMER

6000V

2131

TD10

628A

612

R22

TB11

628

R21

VM1

10NO10

BO10

207

MCB

+MB

jprs

24V SRC

PL18

H633-9

24V SRC

9NO9

207

+PP

PL18

H634-8

TB11

+PP

PL19

H632-9

jprs

BO9

MCB

+MB

+PP

TB11

633A 633B

625

R23

R21

631A

632A 632B

R20

YEL_G632-R

VALVE

ACTUATOR

(FLOATING)

GAS & AIR

MODULATING

BLK WHT

RED_G630-B WHT_G630-W

634A 634B

628

413

YEL_G633-1

YEL_G634-2

COM

OPEN

(CL)

(OP)

CCW

H603-1

+PP

PL16

S1/2.01

600

601

201A

602

603

604

605

606

607

608

609

610

611

612

613

614

615

616

617

618

619

620

621

622

623

624

625

626

627

628

629

630

631

1.POWER, PILOT & MAIN VALVE INDICATION

NOTE:

632

(FSG) CONTROLLER.

LIGHTS ARE PART OF THE FLAMESAFEGUARD

IS THE SECOND VALVE OF A REDUNDANT

2. GV-A IS THE FIRST VALVE AND GV-B

633

COMBINATION VALVE WITH PRESSURE

REGULATION AND MANUAL SHUTOFF

634

635

64 McQuay IM 791-2

636

Wiring Diagrams

COCK

SHUTOFF

(THRU 1/2 P.S.I.)

COCK

SHUTOFF

PIPING DIAGRAM

WHEN 120 VOLT

--FIRST

VALVE AND

GV1A

MANUAL VALVE.

REG.

HIGH PRESS.

OVER 1/2 P.S.I.

(TYPICAL)

PRESS. REG.

GV4B GV4A

GV5B GV5A

--MAIN

VALVE AND

COMBINATION GAS CONTROLS

GV1B

BURNER

BLOWER

TEST

COCK

MODULATING

ACTUATOR

AIR

SWITCH

SAFEGUARD (FSG). UPON A CALL FOR HEAT, THE CONTROL SYSTEM WILL CLOSE (BO#11) ON THE MAIN CTRL BRD (MCB), THUS ENERGIZING RELAY (R20).

WHEN THE ROOFTOP UNIT IS ENERGIZED 120 VOLT POWER IS SUPPLIED TO THE SYSTEM ON-OFF SWITCH (S1), TO BURNER ON-OFF SWITCH (S3) AND 24 VOLTS TO THE (BO#11)

CONTACTS ON THE MAIN CTRL BRD (MCB). BURNER ON-OFF SWITCH (S3) WILL POWER THE MODULATING GAS VALVE ACTUATOR (VM1) AND TERMINAL #5(L1) ON THE FLAME

PREPURGE PERIOD WILL BEGIN.

BLOWER MOTOR (BM). WHENEVER POWER IS RESTORED TO THE FLAME SAFEGUARD, THE FLAME SAFEGUARD WILL GO THROUGH A 10 SECOND INITIATION PERIOD BEFORE THE

CONTROL (FLC) AND TERMINAL #6 ON THE FLAME SAFEQUARD (FSG) IS POWERED. THE FLAME SAFEGUARD THEN ENERGIZES ITS TERMINAL #4, WHICH POWERS THE BURNER COMBUSTION AIR

POWER IS FURNISHED THROUGH THE SYSTEM ON-OFF SWITCH (S1), THROUGH THE BURNER ON-OFF SWITCH (S3), THROUGH RELAY (R20 CONTACTS, THROUGH THE HIGH LIMIT

FOR A NEW CALL FOR HEAT, (VM1) THROUGH THE N/O CONTACTS OF (R20) AND THE N/C CONTACTS OF (R21), WILL RE-POSITION THE BURNER AIR VALVE TO ITS MAXIMUM OPEN

(VM1), THROUGH THE N/C CONTACTS OF (R20) AND (R23), POSITIONS THE BURNER AIR AND GAS CONTROL VALVES TO MINIMUM AFTER A RUN CYCLE. WHEN (R20) IS ENERGIZED

THE AIR CONTROL VALVE WILL BE RE-POSITIONED TO THE MAXIMUM POSITION FOR THE PREPURGE AND THEN RETURNED TO THE MINIMUM POSITION FOR LOW FIRE START.

THE BURNER AIR CONTROL VALVE WILL BE AT THE MINIMUM POSITION DURING OFF CYCLES. UPON A CALL FOR HEAT OR ANY OTHER TIME THAT A PREPURGE CYCLE OCCURS

AIR SWITCH (AS). THIS INITIATES THE 60 SECOND PREPURGE CYCLE. CONCURRENTLY, (LS2) POWERS TIMER (TD10) WHICH WILL ENERGIZE RELAY (R21) AFTER 20 SECONDS.

POSITION FOR PREPURGE. WHEN THE AIR CONTROL VALVE REACHES THE FULL OPEN POSITION SWITCH (LS2) IS 'MADE', POWERING (FSG) TERMINAL #7 THROUGH THE BURNER

TEST

CONN.

IGNITION PERIOD TERMINAL #10 (IGNITION TRANSFORMER--IT) WILL BE DE-ENERGIZED AND TERMINAL #9 (RELAY R23 COIL AND MAIN GAS VALVES--GV4 & GV5) WILL BE ENERGIZED

TERMINAL #10 (IGNTION TRANSFORMER--IT) WILL BE ENERGIZED. IF FLAME IS BEING DETECTED THROUGHT THE FLAME ROD (FD) AT THE COMPLETION OF THE 10 SECOND TRIAL FOR

AFTER COMPLETION OF THE 60 SECOND PREPURGE PERIOD THERE WILL BE A 10 SECOND TRIAL FOR IGINITION DURING WHICH TERMINAL #8 (COMBINATION GAS VALVE--GV1) AND

AND THE CONTROL SYSTEM WILL BE ALLOWED TO CONTROL THE FIRING RATE. THE FLAME SAFEGUARD CONTAINS "LEDS"(LOWER LEFT CORNER) THAT WILL GLOW TO INDICATED OPERATION.

(LS1) WILL BE 'MADE'. IF (LS1) IS NOT 'MADE' THE COMBINATION GAS CONTROL START VALVES (GV1) WILL NOT OPEN AND THE BURNER WILL GO OUT ON SAFETY LOCKOUT.

N/C CONTACT OF (R23). AT THE COMPLETION OF THE 60 SECOND PREPURGE CYCLE THE VALVE WILL BE AT THE MINIMUM OPEN POSITION AND THE MINIMUM POSITION SWITCH

WHEN (R21) IS ENERGIZED (VM1) WILL START THE AIR CONTROL VALVE ON ITS WAY TOWARD THE MINIMUM AIR VALVE POSITION THROUGH THE N/O CONTACT OF (R21) AND THE

THE BURNER AIR AND GAS VALVES FOR THE REQUIRED FIRING RATE. WHEN THE MAIN CONTROL SYSTEM CLOSES (BO#10) ON THE MAIN CTRL BRD (MCB), THE GAS VALVE ACTUATOR

AFTER THE FLAME HAS LIT AND BEEN PROVEN, RELAY (R23) IS ENERGIZED ALLOWING (VM1), AS CONTROLLED BY (BO#9) & (BO#10) ON THE MAIN CTRL BRD (MCB), TO POSITION

AT ITS PRESENT POSITION. THE HEATING CAPACITY IS MONITORED BY THE MAIN CTRL BRD (MCB) THROUGH (AI#10) VIA A POSITION FEEDBACK POTENTIOMETER ON THE ACTUATOR.

THE ACTUATOR WILL RE-POSITION TOWARD A LOWER FIRING RATE. IF NEITHER (BO#9) OR (BO#10) ON THE MAIN CONTROL BOARD (MCB) ARE CLOSED, THE ACTUATOR WILL REMAIN

WILL RE-POSITION TOWARD A HIGHER FIRING RATE UNTIL (BO#10) OPENS OR THE ACTUATOR REACHES ITS MAXIMUM POSITION. WHEN THE MAIN CONTROL SYSTEM CLOSES (BO#9),

INPUT #5 ON THE MICROTECH II MAIN CONTROL BOARD (MCB).

TERMINAL #3 WILL ENERGIZE THE HEAT ALARM RELAY (R24), WHICH WOULD THEN ENERGIZE THE REMOTE 'HEAT FAIL' INDICATOR LIGHT AND SEND A FAIL SIGNAL TO BINARY

THUS DE-ENERGIZING THE BURNER AND TERMINAL #3 WILL BECOME ENERGIZED. THE FLAME SAFEGUARD WOULD THEN BE ON SAFETY LOCKOUT AND WOULD REQUIRE MANUAL RESETTING.

IN THE EVENT THE FLAME FAILS TO IGNITE OR THE FLAME SAFEGUARD FAILS TO DETECT ITS FLAME WITHIN 10 SECONDS, TERMINALS #4, 8, 9, AND 10 WILL BE DE-ENERGIZED,

THE EARLIER DESCRIBED PREPURGE CYCLE WITH THE WIDE OPEN AIR VALVE WILL BE REPEATED.

IF AN ATTEMPT IS MADE TO RESTART THE BURNER BY RESETTING THE FLAME SAFEGUARD, OR IF AN AUTOMATIC RESTART IS INITIATED AFTER FLAME FAILURE,

IF THE UNIT OVERHEATS, THE HIGH LIMIT CONTROL (FLC) WILL CYCLE THE BURNER, LIMITING FURNACE TEMPERATURE TO THE LIMIT CONTROL SET POINT.

SEQUENCE OF OPERATION

641

642

643

644

645

646

647

648

649

650

651

652

653

654

655

656

657

658

659

660

661

662

663

664

665

666

667

668

McQuay IM 791-2 65

Unit Options

Non-Chemical Water Treatment

The McQuay Chemical Free Water Treatment System is designed to prevent scale build-up and microbial growth in the moisture-laden condenser section of McQuay evaporative condenser rooftop units. It has several advantages over traditional chemical treatment systems and functions in the following ways (see IM 827 for more details):

• Changes precipitate formation from surface nucleation

(scale) to colloidal nucleation (bulk-solution powder).

• Keeps systems free from mineral scale on the fill material,

pipes, heat exchangers, and other components in the system.

• Controls the population of microorganisms such as bacteria

and algae by incorporating them into colloidal precipitates

• (encapsulation) or damaging them with pulsed electric fields

(electroporation).

Enthalpy Control

Outside Air Enthalpy Control (OAE)

Units with MicroTech II control and an economizer come standard with an electromechanical enthalpy control device (OAE) which senses both the humidity and temperature of the outside air entering the unit. This device has an enthalpy scale marked A through D. Table 7 shows the control points at 50% RH for settings A through D. Figure 47 shows this scale on a psychrometric chart. When the outside air conditions exceed the setting of the device, the outside air dampers are positioned to the minimum outside air intake position by the MicroTech II controller.

Table 7: Enthalpy Control Settings

CONTROL CURVE CONTROL POINT

TEMP. AT 50% RH A 73°F (23°C) B 70°F (21°C) C 67°F (19°C) D 63°F (17°C)

Differential Enthalpy Control (OAE/RAE)

An optional electric differential enthalpy control arrangement (OAE/RAE) is available on units with MicroTech II control. In this configuration a solid-state humidity and temperature sensing device is located in both the return (RAE) and outside intake (OAE) airstreams. This OAE device has the same A through D scale as the device described above. However, with the OAE/RAE arrangement the switch on OAE must be set all the way past the “D” setting. With this done, the MicroTech II controller will adjust the return and outside air dampers to use the airstream with the lowest enthalpy.

Ground Fault Protection

The ground fault protection is designed to protect motors from destructive arcing ground faults. The system consists of a ground fault relay and a ground fault current sensor. The ground fault relay employs solid state circuits that will trip and open a set of relay contacts in the 115 volt control circuit to shut the unit down whenever a ground fault condition exists. The ground fault relay is self powered. The ground fault sensor is a current transformer type of device located on the load side of the power block through which the power wires of all phases are run.

Figure 47: Enthalpy Control Settings

8 5

9 0

9 5

1 0 0

( 2 9 . 5 )

4 6

4 4

4 2

8 0

( 2 6 . 5 )

4 0

3 8

3 6

3 4

3 2

3 0

2 8

2 6

E N T H A L P Y  B T U P E R P O U N D D R Y A I R

2 4

2 2

2 0

1 8

1 6

1 4

1 2

( 1 . 5 )

3 5

( 1 . 5 )

4 5 ( 7 )

4 0

( 4 . 5 )

3 5

4 0

4 5

( 4 . 5 )

( 7 )

6 0

( 1 5 . 5 )

5 5

( 1 3 )

5 0

( 1 0 )

5 0

5 5

6 0

( 1 0 )

( 1 3 )

( 1 5 . 5 )

( 1 8 . 5 )

6 5

( 1 8 . 5 )

7 5

( 2 4 )

7 0

( 2 1 )

6 5

7 0

7 5

( 2 1 )

( 2 4 )

( 3 2 )

0 . 8 0

0 . 9 0

0 . 7 0

0 . 6 0

0 . 5 0

8 0

8 5

9 0

( 2 6 . 5 )

( 2 9 . 5 )

( 3 2 )

1 0 5

( 3 5 )

( 3 8 )

( 4 0 . 5 )

R E L A T I V E

H U M I D I T Y

0 . 4 0

0 . 3 0

0 . 2 0

0 . 1 0

9 5

1 0 0

1 0 5

0 . 5 )

( 3 5 )

( 3 8 )

( 4

Phase Voltage Monitor

The phase voltage monitor protects against phase loss (single phasing) when any one of three line voltages drops to 74% or less of setting. This device also protects against phase reversal when improper phase sequence is applied to equipment, and low voltage (brownout) when all three line voltages drop to 90% or less of setting. An indicator run light is “on” when all phase voltages are within specified limits. The phase voltage monitor is located on the load side of the power block with a set of contacts wired to the 115 volt control circuit to shut the unit down whenever the phase voltages are outside the specified limits.

66 McQuay IM 791-2

Unit Options

odule

MicroTech II™ Remote User Interface (UI)

Both a unit mounted and remote mounted keypad and display are provided with this option. The unit mounted and remote mounted UI are identical. The following items are provided:

• Unit mounted UI

• Unit mounted power supply and R485 isolator for the

remote UI

• Selector switch to activate either the unit mounted UI or the

remote UI. Only one UI is active at a time.

• Wall mounted electrical box that contains the remote UI. Remote wiring to connect the unit to the remote UI is not

included. Refer to “Cable and Wiring Recommendations”.

Cable and Wiring Recommendations

• No more than 1,000 feet of wiring can be used to connect the

remote user interface to the unit.

• Use overall foil shield, 3 twisted pairs, 22 AWG stranded

connectors with drain wire.

• UL 910 plenum rated = Belden 6542FE-1000-877

• Non-plenum rated = Belden 5542FE-1000-8

Figure 48: Factory-Assembled Remote User Interface

7.2 "

6.9 "

Enclosure with Cover

Surface Mount, Modular Jack with 6 contacts, Screw Te rminals

Cable Assembly

4.4 "

(4) #6-32 Hex Nuts

(4) #6 Split Lock Washers

Keypad/Display M

Ground

Figure 49: Remote User Interface Wiring Diagram

Part Winding Start

The part winding start option is used to reduce the locked rotor inrush current of the compressor motors or the fan motors (208/230 volt units).

The motor has dual windings which are energized with dual contactors. The first contactor closes, energizing one winding. A time delay relay closes the second contactor about one second later, energizing the second winding and bringing the

motor up to full speed. Figure 50 is a typical wiring schematic showing part winding start.

Figure 50: Part Winding Start

McQuay IM 791-2 67

Unit Options

Hot Gas Bypass

Hot gas bypass is a system for maintaining evaporator pressure at or above a minimum value. The purpose for regulating the hot gas into the distributor is to keep the velocity of the refrigerant as it passes through the evaporator high enough for proper oil return to the compressor when cooling load conditions are light.

The system consists of a combination of solenoid valves and a pressure regulating valve as shown in Figure 51. The solenoid valves are factory wired to open whenever the controller calls for the first stage of cooling. The pressure regulating valve starts to modulate open at 57 psig (393 kPa).

Figure 51: Hot Gas Bypass System

Hot gas bypass line,

circuit #1

Hot gas bypass line,

circuit #2

Combination modulation

and solenoid valves

The regulating valve opening point can be determined by slowly reducing the system load or reducing the required discharge air temperature setting while observing the suction pressure. When the bypass valve starts to open, the refrigerant line on the evaporator side of the valve will begin to feel warm

to the touch.

CAUTION

Do not touch gas liner during valve checkout. The hot gas line can become hot enough in a short time to cause personal injury.

To evaporator

External Time Clock

An external time clock can be used as an alternative to (or in addition to) the MicroTech II controller's internal scheduling function. The external timing mechanism is set up to open and close the circuit between field terminals 101 and 102. When the circuit is open, power is not supplied to digital input BI1 on the MCB. This is the normal condition in which the programmable internal schedule is followed. When the circuit is closed, the MicroTech II controller responds by placing the unit in the occupied mode, overriding any set internal schedule.

For more information, please see the “Digital Inputs” section of Bulletin No. IM 696, MicroTech II Applied Rooftop Unit Controller.

Smoke Detectors

Optional smoke detectors can be located at the supply and return openings. The wiring for these smoke detectors is shown on any of the “Typical Main Control Circuit” wiring schematics within the section Wiring Diagrams‚ page 47.

The sequence of operation for these detectors is as follows: When the smoke is detected by either sensor, the normally closed sensor contacts open. This removes power from digital input MCB BI8 on the Main Control Board.

The MicroTech II controller responds by shutting the unit down. The controller is placed in the Alarm Off state, and cannot be restarted until the alarm is manually cleared. Refer

to the operation manual supplied with the unit for information on clearing alarms (OM138 or OM137).

The smoke detectors themselves must be manually reset once they have tripped. Power must be cycled to the smoke detector to reset.

Freeze Protection

An optional freezestat is available on units with MicroTech II control that have hot water o r steam heating coils. The sensing element is located on the downstream side of the heating coil in the heating section of the unit. If the freezestat detects a freezing condition and closes, the MicroTech II controller will take different action, depending on whether the fans are on or off. The freezestat is an auto reset type of control; however, the controller alarm it causes is a manual reset if the fan is on and auto reset if the fan is off.

Fan On Operation

If the freezestat detects a freezing condition while the fan is on, the MicroTech II controller will shut down the fans, close the outdoor air dampers, open the heating valve, and set a 10minute timer. The MicroTech II controller's active alarm will be “Freeze Stat Fault.”

When the 10-minute timer expires, the controller begins checking the freezestat again. If the freezestat is open, the heating valve will close. If the freezestat closes again, the heating valve will open, and the 10-minute timer will reset.

The unit will remain shut down until the “Freeze Stat Fail” alarm is manually cleared. Refer to the operation manual

68 McQuay IM 791-2

Unit Options

supplied with the unit for information clearing alarms (OM138 or OM137).

Fan Off Operation

If the freezestat detects a freezing condition while the fan is off, the MicroT ech II controller will open the heating valve and set a 10-minute timer. The MicroTech II controller's active alarm will be “Freeze Problem.”

When the freezestat opens again, the “Freeze Stat Prob” alarm automatically clears. This feature protects the coil and allows the system to start normally after a cold night.

Low Airflow Alarm

An EFT sensor and an associated “Low Airflow Alarm” are provided on VAV units with MicroTech II control and gas or electric heat. The EFT sensor is located in the supply fan section of the unit at the supply air funnel.

Heat will be disabled whenever the airflow is detected to be too low for safe heating operation. This condition is indicated when the supply air temperature exceeds the mixed air temperature by more than 60°F (16°C). In this case, a “Low Airflow Alarm” is generated and heat will not be re-enabled until the alarm is manually cleared. Refer to the operation manual supplied with the unit for information on clearing alarms (OM138 or OM137).

Duct High Pressure Limit

The duct high pressure limit control (DHL) is provided on all VAV units, including the CAV-DTC unit that can be field converted to VAV. The DHL protects the ductwork, the terminal boxes, and the unit from over pressurization which could be caused by, for example, tripped fire dampers or control failure.

The DHL control is factory set to open when the discharge plenum pressure rises to 3.5" w.c. (872 Pa). This setting should be correct for most applications; however, it is adjustable. Removing the front cover of the device reveals a scale showing the current setting. Turning the adjustment screw located on the bottom of the device adjusts the setting up or down.

If the DHL switch opens, digital input MCB BI 14 on the Main Control Board will be de-energized. The MicroTech II controller then shuts down the unit and enters the Off-Alarm state. The alarm must be manually cleared before the unit can start again. Refer to the operation manual supplied with your unit for more information on clearing alarms (OM138 or OM137).

Condensing Unit VFD Operation

V a riable Frequency Drive Operation

Refer to the vendor instructions supplied with the unit.

Convenience Receptacle/Section Lights

A convenience receptacle is provided in the main control box on all units. To utilize this receptacle, a separate field supplied 115V power wir ing circuit must be connected to the 1 15V field terminal block TB1, located in the main control box. Note that the National Electrical Code requires that this circuit be protected by a ground fault circuit interrupter (GFCI) device.

Optional lights are available for certain sections in the unit. Each light includes a switch and convenience receptacle, and is powered by the external 115V power supply connected to TB1.

DesignFlow™ Outdoor Air Damper Option

DesignFlow™ airflow measurement stations are located inside the louvered outdoor air intake doors between the intake louver and outside air dampers. Essentially, they consist of a vane that is repositioned by airflow, the amount of rotation indicating the amount of airflow. They are calibrated precisely at the factory and no further calibration is required. However, a leveling adjustment is required in the field so that the DesignFlow unit is in the same orientation as when it was factory calibrated. See “DesignFlow Station Startup” below.

The rotational position of the DesignFlow unit vane is translated into CFM by the microprocessor in the MicroTech II control system. The position of the vane is determined by two things—the force of the airflow impacting the vane and the gravitational effect on the vane. Gravity is the only factor at the lower CFM end of the range. On a correctly leveled unit, this gravitational effect will be the same as when the unit was calibrated in the factory.

Accurately leveling a station involves applying a precise mechanical force against the vane. This force should cause the vane to move to a specific position if the DesignFlow unit is correctly leveled.

DesignFlow Station Startup

• Before initial startup of the rooftop unit, carry out the

following procedure on both the right-hand (control panel side) and left-hand (side opposite the control panel) DesignFlow station vanes (see Figure 52).

Note: This procedure is much easier to carry out with two

people—one making the mechanical adjustments and the other viewing and recording readings on the MicroTech II control panel.

Verify that power is supplied to the unit’s MicroTech II control system. The DesignFlow startup procedure cannot be completed without use of the MicroTech II controls.

2 Unlock and open the louvered outdoor air intake door on

the side of the unit (see Figure 52).

See Sequences of Operation‚ page 41.

McQuay IM 791-2 69

Unit Options

3 The swinging vane on the measurement station is locked in

place for shipment. Unlock it by removing the two shipping screws. One is located one inch from the top of the vane and the other one inch from the bottom of the vane. Both are about eight inches in from the outer edge of the vane.

4 Examine the station for shipping damage. Manually rotate

the vane and verify that it does not rub against anything.

Figure 52: DesignFlow Station

Manually hold the vane closed against the mechanical stop at the top of the assembly. Then, read the current vane leveling position on the MicroTech II keypad/display.

Do this by viewing the LH Lvl Pos= or RH Lvl Pos= parameter in the DesignFlow setup menu. The LH Lvl Pos= parameter indicates the current position of the vane for the left-hand DesignFlow station (side opposite the control panel). The RH Lvl Pos= parameter indicates the current position of the vane for the right-hand DesignFlow station (control panel side).

Important: Wait several seconds until the value on the keypad stabilizes before taking the reading.

For detailed information regarding operation and navigation through the unit keypad, refer to Operation manual OM 137 (discharge air control units) or OM 138 (zone control units).

6 Confirm the value of the reading. Ideally, it should read

close to 20.00 (19.50 to 20.50 is acceptable). If the reading is out of range, loosen the screws fixing the mechanical stop at the top of the assembly, make a small adjustment, and recheck until the reading is in the specified range.

Note: Generally, adjustments should not be necessary.

Locate the leveling component kit, which is shipped with the unit, in the unit mail control panel.

8 Duct tape the fulcrum alignment plate to the bottom corner

of the vane (see Figure 53) aligning it as follows:

a The bottom edge of its notches should be flush with the

bottom edge of the vane.

b The side of one notch should be even with the bend near

the outer edge of the vane.

c The plate should be flat against the outer surface of the

vane.

Figure 53: Tape Fulcrum Alignment Plate to Vane

Vane

Duct tape

This edge flush with bottom of vane

These edges flush with bottom of van

Locate and install the fulcrum used in the leveling

Alignment plate

Fulcrum Duct tape

procedure as follows (see Figure 53):

a Wipe the bottom of the louver door where the fulcrum

will be located so that the duct tape will stick to it.

b Pre-apply duct tape to the top surface of the bottom

portion of the fulcrum, extending it about one inch beyond the edges on three sides.

c With the alignment plate taped to the vane and the vane

in the zero airflow position, locate the fulcrum parallel to and against the alignment plate.

Note: The zero airflow position is when the vane is swung

away from the back wall and gently resting against its stop.

Once the fulcrum is in position, press the duct tape extensions down to hold the fulcrum in place.

e Remove the alignment plate after installing the fulcrum. 10 Close and latch the louvered intake door. 11 Remove the cover from the access opening in the bottom

blade of the outdoor air intake louver (see Figure 56).

12 Verify that the unit fans are off and that the outdoor air

dampers are closed. If there is a wind, cover the outdoor air louvers with poly film, cardboard, or other suitable material to prevent adverse readings due to wind.

13 Rest the leveling weight assembly on the fulcrum, as shown

in Figure 54, so that:

a Its bottom two thumbscrews rest on the top edge of the

fulcrum.

b Its top thumbscrew rests against the vertical alignment

mark on the vane.

Note: The alignment mark is locate d 0.50 inch in from the

bend on the outer edge of the vane. It intersects with a hole located one inch up from the bottom outer edge of the vane.

70 McQuay IM 791-2

Unit Options

Figure 54: Place Leveling Weight on Fulcrum

involves precisely pivoting the assembly with a known force applied to the vane until the vane opens to a specific position.

If after performing Steps 13 through 15 (previous page), the vane does not come to rest within the specified range, carry out the following steps:

1 Unlock and open the louvered outdoor air intake door on

the side of the unit.

2 Loosen the two .25-20 NC lock nuts at the top of the

DesignFlow frame (see Figure 55).

Figure 55: DesignFlow Frame

Top lock nuts

Vane

Pivot point

Set up the leveling test as follows:

a While holding the weight so it stays on the fulcrum,

manually rotate the vane to the wide-open position, manually return it to the zero CFM position, and gently release the vane.

b Locate the leveling weight assembly so its contact point

is against the vertical mark on the vane.

c While the weight assembly teeters on the fulcrum,

gently rap the base frame to slightly vibrate the assembly and encourage the vane to seek its equilibrium point.

15 Read the current LH Lvl Pos= (or RH Lvl Pos=) parameter

in the DesignFlow Setup menu on the keypad/display. These parameters vary from 20% to 80% depending on the position of the DesignFlow vane

16 If the value indicated by the LH Lvl Pos= (or RH Lvl Pos=)

parameter is not within the range of 23.64% to 24.08%, adjust the level of the DesignFlow unit using the procedure described in “Making Level Adjustments” below.

17 When the LH Lvl Pos= (or RH Lvl Pos=) value is in range,

remove the fulcrum and leveling weight assembly and replace the access opening cover in the louvered door.

Making Level Adjustments

The DesignFlow unit is mounted so that it pivots at the top when three lock nuts are loosened, two at the top and one at the bottom of the assembly (see Figure 55). Leveling the unit

Bottom lock nut

3 Close and lock the intake door. 4 Remove the cover from the access opening in the bottom

blade of the outdoor air intake louver (see Figure 56).

5 Loosen the .25-20 NC lock nut in the slotted hole at the

bottom of the DesignFlow frame (see Figure 57).

6 If the LH Lvl Pos= (or RH Lvl Pos=) value obtained in

step 15 above is HIGHER than the specified range, move the bottom of the DesignFlow frame closer to the outdoor air dampers (away from the back end of the unit). Do this by turning the long adjuster nut to increase the L dimension in Figure 57.

If the LH Lvl Pos= (or RH Lvl Pos=) value obtained in step 15 above is LOWER than the specified range,

move the bottom of the DesignFlow frame away from the outdoor air dampers (toward the back end of the unit). Do this by turning the long adjuster nut to decrease the L dimension in Figure 57.

Note: If the necessary adjustment cannot be made using

the long adjuster nut, reposition the two .25-20 NC jam nuts on the threaded rod to make larger adjustments (see Figure 57).

When finished making the adjustments, tighten the .25-20 NC lock nut in the slotted hole at the bottom of the DesignFlow frame (see Figure 57).

8 Gently rap the base frame to slightly vibrate the assembly

to encourage the vane to seek its equilibrium point.

McQuay IM 791-2 71

Unit Options

9 Recheck the vane position compared to the range specified

in Step 16 (previous page). Readjust the level as necessary.

10 When the level is correct, unlock and open the louvered

outdoor air intake door on the side of the unit and tighten the two .25-20 NC lock nuts at the top of the DesignFlow frame (see Figure 55).

11 Close and lock the intake door. 12 Recheck the vane position and read just th e level as

necessary.

13 When the vane position is correct, replace the access

opening cover in the louvered door.

Figure 56: Remove Covers From Access Opening

Louvered door

is similar to that for supply fans and covered in other sections of this manual.

Figure 58: 2 Fans with Back Return Shown

F a n a n d M o t o r A s s e m b l i e s

Access opening

Cover

Figure 57: Leveling Adjustment

Threaded adjuster

assembly

Long adjuster nut

Jam nuts

To INCREASE L dimension

Right hand adjuster Left hand adjuster

To INCREASE L dimension

Locknut

Propeller Exhaust Fan Option

Economizer units may include propeller exhaust or centrifugal return fan options. This section covers maintenance and operating instructions for the propeller exhaust option. Centrifugal return fan construction, maintenance and operation

V F D

S t a r t e r s

Prestarting Checks

Check all fasteners and set screws for tightness. This is especially important for bearing set screws.

The propeller should rotate freely and not rub on the fan panel venturi. Rotation direction of the propeller should be checked by momentarily turning the unit on. Rotation should be in the same direction as the rotation decal affixed to the unit or as shown in Figure 59, page 73. For 3-phase installations, fan rotation can be reversed by simply interchanging any two of the three electrical leads. For single phase installations follow the wiring diagram located on the motor.

The adjustable motor pulley is preset at the factory for the specified fan RPM. Fan speed can be increased by closing or decreased by opening the adjustable pulley. Two or three groove variable pitch pulleys must be adjusted an equal number of turns open. Any increase in fan speed represents a substantial increase in horsepower required from the motor. Always check motor load amperage and compare to name plate rating when changing fan speed.

72 McQuay IM 791-2

Unit Options

Figure 59: Fan Rotation

i r f l o w

R o t a t i o n

A i r f l o w

R o t a t i o n

Once the fan has been put into operation, establish a periodic maintenance program to preserve the reliability and performance of the fan. Items to be included in this program are:

• Belts

• Bearings

• Fasteners

• Setscrews

• Lubrication

• Removal of Dust/Dirt

Figure 60: Belt Adjustment

D e f l e c t i o n =

B e l t S p a n

Figure 61: Drive Pulley Alignment

M u s t b e p a r a l l e l

B e l t S p a n

6 4

Belts

WARNING

Rotating fan and motor belts can cause severe personal injury or death.

Secure all loose clothing, hair, jewelry and tools to avoid entrapment.

M o t o r

B e a r i n g

C e n t e r l i n e s m u s t c o i n c i d

Premature belt failures are generally caused by improper belt tension (either too tight or too loose) or misaligned pulleys. The proper tension for operating a V-belt is the lowest tension at which the belts will not slip at peak load conditions. For initial tensioning, the proper belt deflection half way between pulley centers is 1/64" for each inch of belt span. For example, if the belt span is 64 inches, the belt deflection should be one inch using moderate thumb pressure at midpoint of the drive, See Figure 60, page 73.

M u s t b e p a r a l l e l

A d j u s t a b l e S h e a v e

Check belt tension two times during the first 24 hours of operation and periodically thereafter. To adjust belt tensio n, simply loosen four fasteners (two on each side of the motor plate) and slide the motor plate away from the fan shaft until proper belt tension is attained. On some fans, fasteners attaching the motor to the motor plate must be loosened in order to adjust the belt.

It is very important that the drive pulleys remain in proper alignment after adjustments are made. Misalignment of pulleys will result in premature belt wear noise, vibration and power loss. See Figure 61, page 73.

Bearings

Bearings are the most critical moving part of the fan and should be inspected at periodic intervals. Locking collars and set screws, in addition to fasteners attaching the bearings to the bearing plate, must be checked for tightness. In a clean environment and temperatures above 32°F./below 200° F., fan shaft bearings with grease fittings should be lubricated semiannually using a high quality lithium based grease. If unusual environmental conditions exist temperatures below 32°F/ above 200°F, moisture or contaminants, more frequent lubrication is required.

McQuay IM 791-2 73

Unit Options

With the unit running, add grease very slowly with a manual grease gun until a slight bead of grease forms at the seal. Be careful not to unseat the seal by over lubricating or using excessive pressure. Bearings without grease fittings are lubricated for life.

Fasteners and Setscrews

Any fan vibration has a tendency to loosen mechanical fasteners. A periodic inspection should include checking all fasteners and set screws for tightness. Particular attention should be paid to setscrews attaching the propeller to the shaft and the shaft to the bearings. Loose bearing set screws will lead to premature failure of the fan shaft.

Lubrication

Refer to Bearings‚ page 73 for bearing lubrication. Many fractional horsepower motors installed on the smaller fans are lubricated for life and require no further attention. Motors equipped with oil holes should be oiled in accordance with the manufacturer's instructions printed on the motor. Use a high grade SAE 20 machine oil and use caution not to over lubricate.

Motors supplied with grease fittings should be greased according to directions printed on the motor.

Removal of Dust/Dirt

Dirt clogs cooling openings on the motor housing, contaminates bearing lubricant and collects on propeller blades causing severe imbalance if left unchecked. The exterior surface of the motor, fan panel and entire propeller should be thoroughly cleaned periodically. Use caution and do not allow water or solvents to enter the motor or bearings. Under no circumstances should motors or bearings be sprayed with steam or water.

Propeller Exhaust Fan Control

Exhaust Fan On/Off Control

The Exhaust fans are turned on and off based on building static pressure, outdoor air damper position, and discharge fan capacity. Exhaust fans do not have to always run while the supply fan is on, as the does a return fan. They are turned on and off through DO # 2 on the Mod DCU as described below.

The Exhaust Fans are turned on when:

• All of the following are true for longer than the Min Start

Time (Default Time = 120 Seconds):

– OA Damper Capacity exceeds Min OA Dmpr Pos – Either the Discharge Fan Capacity exceeds the Min DF

Cap or the Discharge Fan Control Type is Constant Vo lume. This two part condition may be able to be reduced to one condition if there is one attribute that is set to 100% when constant volume units are on and to the current fan speed or actuator position for variable air volume units.

– The type of control (RF/EF Ctrl) is set to Building Pres-

sure

– The building static pressure is above the building static

pressure setpoint by more than the deadband/2.

• All of the following are true for longer than the Min Start

Time (Default Time = 120 Seconds).

– OA Damper Capacity exceeds Min OA Dmpr Pos – The Discharge Fan Capacity exceeds the Min DF Cap or

the Discharge Fan Control Type is Constant Volume. This two part condition may be able to be reduced to one condition if there is one attribute that is set to 100% when constant volume units are on and to the current fan speed or

actuator position for variable air volume units. – The type of control (RF/EF Ctrl) is set to Position – The Exhaust Fan VFD capacity (Rem RF/EF Cap) is set to

a value above the Min Exh Fan Cap (Default = 25%) .

The Exhaust Fans are turned off when:

• All of the following are true:

– The type of control (RF/EF Ctrl) is set to Building Pres-

sure – The building static pressure is below the building static

pressure setpoint by more than the deadband/2 – The Exhaust Fan capacity is at the Min Exh Fan Cap

(Default = 25%) or lower for longer than the Min Stop

Time (Default Time = 120 Seconds).

• Both of the following are true:

– The type of control (RF/EF Ctrl) is set to Position – The Remote Exhaust Fan capacity setpoint (Rem RF/EF

Cap) is set below the Min Exh Fan Cap (Default = 25%)

for longer than the Min Stop Time (Default Time = 120

Seconds).

• The unit is off

Exhaust Fan Speed Control

The exhaust fan variable frequency drive can be cont rolled by two different methods that maintain building static pressure. Fan tracking is not provided with exhaust fans. The Exhaust Fan VFD speed is increased through MCB-BO16 and decreased through MCB-BO15 just like the Return Fan.

Set the minimum speed of the Exhaust Fan to Min Exh Fan Cap (Default = 25%) using the keypad on the VFD. Enter the same minimum speed value through the MicroTech II keypad to provide the capability to turn on and off the Exhaust Fans as described above.

When Building Static pressure is selected, the exhaust variable frequency drive is controlled to maintain building static pressure directly . A mini mum speed is maintained b y the VFD, not by MicroTech II.

74 McQuay IM 791-2

Unit Options

The outputs, MCB-BO15 and MCB-BO16 will be controlled by a Proportional/Integral (PI) algorithm that increases the speed of the VFD in order to lower the building static pressure

When the unit is in an off state, the variable frequency drive is

turned off by turning off MCB-BO2. At the same time, MCB-

BO15 is turned on, and MCB-BO16 is turned off.

and decreases the speed of the VFD in order to raise the building static pressure. The building static pressure will be provided as it is now through MCB-AI14 with a range of - .25 IWC to + .25 IWC. This control algorithm is identical to that

Keypad Entries

Add a new table menu, Exhaust Fan Setup, after Bldg Static P

Setup and before Zone Temp Setup with the following entries.

currently used to control building static pressure using a return fan VFD except that the minimum speed (Default = 25%) is not maintained by MicroTech II.

When position control is selected, the speed of the exhaust fan variable frequency drive is controlled to the Remote RF/EF setting. MCB-BO15 and MCB-BO16 are controlled to maintain a fixed speed provided through a connected network or the keypad. This control algorithm similar to that currently used to control a return fan VFD to maintain a fixed speed

Exhaust Fan Setup

Min Exh Fan Cap = 25%(1 - 99%)

Min OA Dmpr Pos= 5%(1 - 99%)

Min DF Cap = 10%(1 - 99%)

Min Start Time=120 s(10 - 240 sec)

Min Stop Time=120 s(10 - 240 sec)

except that the minimum speed (Default = 25%) is not maintained by MicroTech II. This minimum speed is maintained by the VFD.

Table 8: Propeller Exhaust Fa n Troubleshooting

Problem Cause Corrective Action

Check backdraft dampers for proper operation. Remove obstructions in ductwork. Clean dirty filters. Check for adequate supply for air exhaust fans or exhaust air for supply fans.

Tighten bearing collars and setscrews. Lubricate bearings. Replace defective bearings.

Tighten pulleys on motor shaft and fan shaft. Adjust belt tension. Align pulleys. Replace worn belts or pulleys.

Clean dirt build-up from propeller. Check all setscrews and fasteners for tightness. Check for worn bearing. Correct propeller imbalance. Check for loose dampers, guards or ductwork.

Reduced Airflow

Excessive Noise

System resistance is too high.

Unit running backwards. See Prestarting Checks‚ page 72 Fan speed too low. Increase fan speed Excessive dirt on propeller. Clean propeller

Bearings

V-Belt drive

Excessive vibration

Defective motor Replace motor.

Figure 62: Propeller Exhaust Replacement Parts List

1 0

1 . F a n P a n e l 2 . P r o p e l l e r 3 . D r i v e F r a m e C h a n n e l ( 2 ) 4 . M o t o r P l a t e 5 . M o t o r 6 .

M o t o r P u l l e y 7 . S h a f t P u l l e y 8 . F a n S h a f t 9 . B e a r i n g s 1 0 . B e l t 1 1 . B e a r i n g P l a t e

McQuay IM 791-2 75

Unit Options

Ultraviolet Lights Option

When this option is employed, ultraviolet C light bathes the moist surfaces on the coil and drain pan, killing most microorganisms that can grow there.

Typically, ultraviolet lights are installed on the leaving side of the cooling coils in the unit. Each light module is mounted on a rail and is removable for convenient bulb replacement.

UV Light Power Disconnect switches (two per door) are factory installed on every door that allows a direct line of sight to the UV lamps when opened. These switches are designed to prevent UV exposure when cabinet doors are opened and must not be disabled.

A viewing window near the UV lights allows viewing to determine if the lights are energized. The viewing windows use specially designed glass that blocks harmful UV light.

CAUTION

UVC exposure is harmful to the skin and eyes. Looking at an illuminated bulb can cause permanent blindness. Skin exposure to UVC can cause cancer. Always disconnect power to unit before servicing. Do not operate if disconnect switch has been disabled.

Figure 63: Typical Ultraviolet Light Installation

Cooling Coil

View Window

AIRFLOW

Light Power Disconnect Switch

Ultraviolet Light Units

Light Power Disconnect Switch

Ultraviolet Light Operation

Refer to the wiring schematic below. 115VAC power for the UV lights is provided by control circuit transformer T1. The lights operate whenever the unit is powered, system switch S1 is closed, and all doors with door power disconnect switches are closed. T o turn the lights off, disconnect power to the entire unit, or open system switch S1.

The normally open disconnect switches are wired in series in a circuit that supplies 24VAC to the coil of relay R45. When all doors are closed, relay R45 is energized, and its normally open contacts (in series with system switch S1) provide 115VAC to the UV lights.

76 McQuay IM 791-2

Figure 64: Typical Ultraviolet Light Wiring Schematic

Unit Options

McQuay IM 791-2 77

Check, Test, and Start Procedures

Check, Test, and St art Procedures

WARNING

Electric shock and moving machinery hazard. Can cause severe equipment damage, personal injury, or death.

Lock out and tag out electrical power before servicing this equipment. All start-up and service work must be performed by trained, experienced technicians. Read and follow this manual: MicroTech II Applied Rooftop Unit Controller manual (Bulletin IM 696), and operation manual (Bulletin OM 137 or OM 138) before operating or servicing. Equipment frame must be bonded to building electrical ground through grounding terminal or other approved means.

All units are completely run tested at the factory to promote proper operation in the field. Nevertheless, the following check, test, and start procedures must be performed to properly start the unit. To obtain full warranty coverage, the check, test, and start form supplied with the unit must be completed, signed, and returned to McQuay International.

A representative of the owner or the operator of the equipment should be present during start-up to receive instructions in the operation, care, and maintenance of the unit.

If the unit has a factory mounted disconnect switch, use the switch’s bypass mechanism to open the main control panel door without de-energizing the control panel (see page 103 for instructions).

Whenever accessing the main control panel while it is still energized, keep the inner deadfront protective panels on to

avoid exposure to high voltage power.

WARNING

Hazardous voltage. Can cause severe injury or death.

Disconnect electric power before servicing equipment. More than one disconnect may be required to de-energize the unit.

Before Start-Up

1 Verify that the unit is completely and properly installed

with ductwork connected. Verify that all construction debris is removed, and that the filters are clean.

2 Verify that all electrical work is complete and properly

terminated. Verify that all electrical connections in the unit control panel and compressor terminal box are tight, and that the proper voltage is connected. Verify all nameplate electrical data is compatible with the power supply. Verify the phase voltage imbalance is no greater than 10%.

3 Verify that gas piping is complete and leak tight. Verify that

the shutoff cock is installed ahead of the furnace, and that all air has been bled from the gas lines.

4 Manually rotate all fans and verify that they rotate freely.

Verify that the belts are tight and the sheaves are aligned.

5 Verify that all setscrews and fasteners on the fan assemblies

are still tight. Do this by reading and following the instructions in “Setscrews” which is in the “Maintenance” section of this manual.

6 Verify that the evaporator condensate drain is trapped, and

that the drain pan is level.

7 If unit is curb mounted, verify that the curb is properly

flashed to prevent water leakage.

8 Before attempting to operate the unit, review the control

layout description to become familiar with the control locations. Review the equipment and service literature, the sequences of operation, and the wiring diagrams to become familiar with the functions and purposes of the controls and devices.

9 Determine which optional controls are included with the

unit.

10 Before closing (connecting) the power disconnect sw itch,

open (disconnect) the following unit control circuit switches:

a Main Control Panel

• Turn system switch S1 to off.

• Electric heat units: turn switch HS1 to off.

b Compressor Compartment

• Turn compressor control circuit switches

CS1, CS2 to off.

• Turn liquid line solenoid valve switches

PS1, PS2, PS3 to off.

c Furnace Control Compartment

• Turn furnace switch S3 to off.

d Main Control Panel Switch S7 to off.

11 If the DAC or SCC unit does not have an optional zone

temperature sensor (ZNT1) connected to it, you may need to change the keypad entry under Setup/Service \ Unit Configuration \ Space Sensor = from “Yes” to “No”

12 If desired, all MicroTech II internal control timers can be

reduced significantly by changing the entry under keypad menu Setup/Service \ Unit Configuration \ Timer Settings \ Service = from “0 min” to “X min” where X is the number of minutes you want to have the unit operate with fast timers.

WARNING

Failure to maintain and continually provide water treatment will result in severe equipment damage and may create biologically hazardous condi t ions.

78 McQuay IM 791-2

Check, Test, and Start Procedures

Power-Up

1 Close the unit disconnect switch. With the control system

switch S1 in the “off” position, power should be available only to the control transformer T1 and the compressor crankcase heaters.

2 Turn the Switch S1 to “on”. Power should now be supplied

to the control panel, and the LED's on MCB1 should follow the normal startup sequence (refer to the “MCB LED Power-Up Sequence” of IM 696).

Fan Start-Up

1 Verify all duct isolation dampers are open. Unit mounted

isolation dampers may be mounted in the supply or return sections.

2 Place the unit into the “Fan Only” mode through the

keypad menu System Summary \ System \ Ctrl Mode = Fan Only.

3 Turn Switch S7 to “on”. The controller should enter the

“Startup Initial” operating state.

4 If the fans are equipped with optional spring isolators,

check the fan spring mount adjustment. When the fans are running they should be level. Refer to RDT Spring Mount

Hold Down Fasteners‚ page 38.

5 Verify the rotation is correct. 6 Verif y the DHL safety is opening at a pressure compatible

with duct working pressure limits.

Note: The supply and return fan drives are usually selected for

operation in the drive's midspeed range. The return fan drives are usually shipped with fixed pitch sheaves that will provide the selected fan speed; however, the supply fan drives are usually shipped with variable pitch sheaves that are adjusted to provide the minimum fan speed. Both drives should be adjusted for proper airflow during air balancing. For more information, refer to Air

Balancing‚ page 82.

Economizer Start-Up

CAUTION

Adjust dampers properly. Improper adjustment may damage the dampers. When an economizer is ordered without an actuator, the linkage requires a 3.14" linear stroke to fully open it. Do not allow dampers to be driven beyond their normal full closed or full open position.

1 Check whether the outdoor air is suitable for free cooling

by displaying the keypad menu T emperature \ OA Damper \ OA Ambient = “Low” indicates low outdoor air enthalpy;

“High” indicates high outdoor air enthalpy. Refer to

Enthalpy Control‚ page 66 to verify that the enthalpy

changeover control is working properly. You may want to take temperature and humidity measurements.

2 Verify that switches PS1 and PS2 are at “off.” This will

prevent compressor operation during the procedure.

3 At the keypad, set the cooling setpoint low enough so that

the controller will call for cooling. The value in T emperatur e \ Zone Cooling \ Occ Clg Spt = will need to be adjusted below the temperature shown in Temperature \ Zone Cooling \ Control Temp =. In addition, on DAC units, the value in Temperature \ Discharge Cooling \ DAT Clg Spt = will need to be adjusted below the temperature shown in Temperature \ Discharge Cooling \ Disch Air =.

4 Place the unit into cooling mode through the keypad menu

System Summary \ System \ Ctrl Mode = Cool Only.

5 Observe the outdoor air dampers:

a If the outdoor enthalpy is low, the control algorithm

should start to modulate the dampers open to maintain the discharge air setpoint.

b If the outdoor enthalpy is high, the dampers should

maintain their minimum position. Look at menu Temperature \ OA Dam per \ MinOA Pos = . Change this entry to another value. Verify that the dampers move to the new minimum position setpoint.

6 If the unit is equipped with the electromechanical enthalpy

changeover control (Honeywell H205) and the outdoor air condition is borderline, attempt to change its input to the MicroT ech II controller by turning the switch adjustment to “A” or “D”. Check enthalpy status in keypad menu Temperature \ OA Damper \ OA Ambient =. If this reading is “Low”, go to step 5a. If it is “High”, go to step 5b.

Note: It may not be possible to check the economizer

operation in both low and high enthalpy states on the same day. If this is the case, repeat this procedure on another day when the opposite outdoor air enthalpy conditions exist.

Evaporative Condenser Start-Up

1 Ve rify that the sump is completely empty and the drain

plugs are fully installed and tight.

2 Open the manual city water valve. Solenoid valve SV61

should be energized by sump water level switch WL63. Supply water piping should be leak tight. Observe the sump begin to fill.

3 Make sure that pumpdown switches PS1, PS2 and PS3 are

turned to “Off”.

4 Turn compressor control circuit switch CS1 to “On”. 5 Ve rify that the compressors remain off. 6 Place a jumper between terminals 57 and 59. If the sump

low water switch is working properly, spray pump M64 will remain off when the sump is empty. If the spray pump turns on without water in the sump, pull the jumper immediately and check the switch and associated wiring.

7 When the water fills past the low water switch WL64, the

spray pump will energize. Observe piping inside the service section and in the condensing section. Make sure piping is water tight and that the spray pattern is completely covering the condensing coil.

McQuay IM 791-2 79

Check, Test, and Start Procedures

8 Remove the jumper and the spray pump should shut down. 9 When the water level reaches WL63, the supply water

solenoid should shut off city water into the unit.

10 If the unit is equipped with the optional sump heater, check

its internal thermostat. Set the dial to a setpoint above the current sump temperature. Measure the current draw of the heater and compare to the heater nameplate data. When finished, put the setpoint back to the desired operating value (about 50°F)

11 If the unit is equipped with optional freeze protection,

check its operation. Go to the evaporative condenser keypad menu and set the sump dump setpoint below the current sump temperature. Solenoid valve SV63 should energize and start the sump draining. Solenoid valve SV61 and spray pump M64 should be de-energized. When finished, change setpoint back to 35°F (default).

Compressor Start-Up

CAUTION

Low ambient temperature hazard. Can cause compressor damage. Do not attempt to start up and check out the refrigeration system when the outdoor air temperature is below 50°F.

With the supply and return fans operational, prepare for compressor operation.

The unit is shipped with refrigeration service valves closed. Backseat (open) the discharge, and liquid line valves. Connect service gauges and crack the valves off the backseat position (one turn forward). Verify that the unit has not lost its refrigerant charge.

Verify that the crankcase heaters are operating. These should operate for at least 24 hours before starting the compressors.

Verify that the condenser fan blades are positioned properly and that the screws are tight (See Figure 65). The fan blade must be correctly positioned within its orifice for proper airflow across the condenser coils.

Figure 65: Condenser Fan Blade Positioning

1.21"

Perform the following procedure:

1 At the keypad, set the cooling setpoint low enough so that

the controller will call for cooling. The value in

T emperatur e \ Zone Cooling \ Occ Clg Spt = will need to be adjusted below the temperature shown in Temperature \ Zone Cooling \ Control Temp =. In addition, on DAC units, the value in Temperature \ Discharge Cooling \ DAT Clg Spt = will need to be adjusted below the temperature shown in Temperature \ Discharge Cooling \ Disch Air =.

2 Place the unit into cooling mode through the keypad menu

System Summary \ System \ Ctrl Mode = Cool Only.

3 Ve rify that the low ambient compressor lockout

temperature setpoint, Temperature \ OA Damper \ OATComp Lock = is set below the current outside air temperature (shown in System Summary \ Temperatures \ OA Temp =).

Note: Do not attempt to operate the compressors if the outdoor air is too cool. See the warning statement under

Compressor Start-Up‚ page 80.

4 Turn pumpdown switch PS3 to “on.” 5 Turn compressor control circuit switch CS1 and pump-

down switch PS1 to “on.” Now refrigeration circuit #1 is enabled and circuit #2 is disabled. Note that if the unit has an economizer and the outdoor air enthalpy is low, the economizer must fully open before the controller will energize mechanical cooling. When the outdoor air damper has fully opened and the internal timer has expired, liquid line solenoid valve SV1 should open. If the solenoid valve does not open, do the following:

a Verify that there is a call for cooling by checking the

keypad menu System Summary \ System \ UnitStatus =. This should be in “Cooling”.

b Check the keypad menu System Summary \ System \ Clg

Status =. The compressors will only run if this reads either “All Clg” or “Mech Clg”.

c Trace the control circuits.

NOTICE

Venting refrigerant to atmosphere is not allowed per most local laws and/or codes.

6 Verify that compressor #1 starts. On units without optional

low ambient start, the compressor should start shortly after the solenoid valve opens. On units with low ambient start, the compressor should start when the solenoid valve opens. If the compressor motor hums but does not run, verify that it is getting three-phase power. The compressor should operate continuously while there is a call for cooling. If the compressor trips on oil pressure, see Oil Pressure‚ page 81. If the compressor cycles on its low pressure switch, do the following:

a Verify that the circuit is not short of refrigerant. b Check for low airflow. c Check for clogged filters. d Check for restricted ductwork. e Check for very low temperature return air entering the

unit.

80 McQuay IM 791-2

Check, Test, and Start Procedures

f Verify that the liquid line components, expansion valve,

and distributor tubes are feeding the evaporator coil.

g Verify that all air handling section panels are closed. h Verify that the suction service valve and the liquid line

service valves are completely open.

7 Verify that the compressors stage properly. As the circuit

loads up the second compressor (if available) will be energized. For more information on staging sequences, see the Binary Outputs-Auxiliary Control Boards section of bulletin IM 696, “MicroTech II Applied Rooftop Unit Controller”

8 Verify that the condenser fans are cycling and rotating

properly (blowing air upward). When the compressor starts, at least one condenser fan should also start. The CCB1 should control the remaining condenser fans based on sump temperature conditions.

9 Check the oil level in the compressor sightglass. If low oil

is observed, it is possible that liquid refrigerant is returning to the compressor. Check the suction superheat, see

Checking Superheat‚ page 81. It should be between 10°F

(5.5°C) and 13°F (7.2°C). See “Expansion Valve Superheat Adjustment”.

10 Close solenoid valve SV1 by turning switch PS1 to “Off.”

The circuit should pump down and then the compressor(s) should stop. Place the unit into the “Fan Only” mode through the keypad menu System Summary \ System \ Ctrl Mode = Fan Only.

Note: Check refrigerant circuit #2 by repeating steps 2

through 10, substituting circuit #2 nomenclature for circuit #1 nomenclature (CS2, PS2, TD2, SV2, CCB2, and compressor #2 (and #4).

Note: The unit is wired for one time pumpdown. The

compressor will not restart on the off cycle even if the low pressure switch closes due to small leaks in the solenoid valve or compressor check valve.

Verify that the condenser refrigerant subcooling at full capacity is between 13 and 20°F.

Expansion Valve Superheat Adjustment

It is very important that the expansion valve superheat setting be adjusted to be between 10°F (-12°C) and 13°F (-11°C) as described in the steps below. Insufficient superheat will cause liquid floodback to the compressor which may result in slugging. Excessive superheat will reduce system capacity and shorten compressor life.

1 Turn the adjustment stem clockwise to increase superheat.

Not exceeding one turn,

2 Adjust the stem and then observe the superheat. Allow up

to 30 minutes for the system to rebalance at the final superheat setting.

On refrigeration circuits with multiple expansion valves, the superheat adjustment should be approximately the same for all valves in the circuit.

Checking Superheat

Following are recommendations for checking superheat:

1 Close the unit section doors. Running the unit with its

doors open will affect expansion valve and system operation considerably.

2 For units with one expansion valve per circuit, check the

pressure and temperature at the compressor suction valve.

3 For units with multiple expansion valves per circuit, check

the pressure at the compressor, and check the temperature at the suction header that is fed by the valve.

Oil Pressure

When the compressor has operated long enough to stabilize conditions, proper oil pressure should be maintained. The actual oil pressure value varies from compressor to compressor and depends upon the temperature, oil viscosity, compressor size, and the amount of clearance in the compressor bearings. Oil pressure values from 20 to 60 psi (138-414 kPa) (over suction pressure) are not uncommon.

The oil level in the compressor sightglass can vary widely and depends upon the same factors listed above. In fact, it is not unusual for two compressors that serve the same circuit to have very different oil levels. Therefore, it is recommended that oil pressure, not sightglass level, be used to judge whether there is enough oil in a refrigerant circuit. If the oil pressure is low, additional oil should be added (use only dry refrigerant grade oil, Sunisco 3GS, Texaco WF32, or Calumet R015).

Note: If low oil level is accompanied by heavy foaming visible

in the oil sightglass, it is possible that excess liquid refrigerant is returning to the compressor. Check the suction superheat and adjust the expansion valve for 10°F (-12°C) to 13°F (-11°C) of superheat.

Heating System Start-Up

General

1 At the keypad, set the heating setpoints high enough so that

the controller will call for heating. The value in T emperatur e \ Zone Heating \ Occ Htg Spt = will need to be adjusted above the temperature shown in Temperature \ Zone Heating \ Control Temp =. In addition, on DAC units, the value in Temperature \ Discharge Heating \ DAT Htg Spt = will need to be adjusted above the temperature shown in Temperature \ Discharge Heating \ Disch Air =.

2 Place the unit into heating mode through the keypad menu

System Summary \ System \ Ctrl Mode = Heat Only.

3 Ve rify that the high ambient heat lockout temperature

setpoint, Temperature \ Zone Heating \ OATHtg Lock = is set above the current outside air temperature (shown in System Summary \ Temperatures \ OA Temp =).

McQuay IM 791-2 81

Check, Test, and Start Procedures

Gas Furnace

Refer to the “Start-up and Operating Procedures” section of the Forced Draft Gas Fired Furnace Installation Manual, Bulletin No. IM 684 or 685. Perform the start-up procedures given in it.

Electric Heat

Turn the electric heat switch HS1 to “On”. The electric heaters should energize. If the unit has multistage electric heat, the MicroTech II Auxiliary Control board EHB1 should energize the heaters in successive stages. The rate of staging is set in keypad menu Setup/Service \ Heating Setup \ Stage Time =. The default value of “5 min” can be adjusted from 2 to 60 minutes.

Steam Heat

The steam valve actuator should open the valve. The steam valve is open when the valve stem is up. If the unit loses power, the spring in the actuator should drive the valve wide open. Check this by opening system switch S1.

Hot Water Heat

The hot water valve actuator should open the valve to the coil. The three-way hot water valve is open to the coil when the valve stem is down. If the unit loses power, the spring in the actuator should drive the valve wide open to the coil. Check this by opening system switch S1.

Air Balancing

Air balancing should be performed by a qualified air balancing technician. Note that the supply fan motors are usually shipped with variable pitch sheaves which are typically set at the low end of the drive's fan rpm range. See Mounting and Adjusting

Motor Sheaves‚ page 83. The return fan motors are usually

shipped with fixed pitch sheaves.

WARNING

Moving machinery hazard. Can cause severe personal injury or death.

Use a strobe tachometer to measure the speed of return fans. Do not use a mechanically driven tachometer on this fan arrangement.

3 For DAC units that are using fan tracking control, adjust

the parameters for the MicroTech II controller's VaneTrol algorithm. For complete information on using this feature, see the “Return Fan Capacity Control” section in Bulletin OM 137, “MicroTech II Applied Rooftop Unit Controller: DAC Control”.

4 When the final drive adjustments or changes are complete,

check the current draw of the supply and return fan motors. The amperage must not exceed the service factor stamped on the motor nameplate.

5 Upon completion of the air balance, replace variable pitch

motor sheaves (if any) with comparably sized fixed pitch sheaves. A fixed pitch sheave will reduce vibration and provide longer belt and bearing life.

Sheave Alignment

Mounting:

1 V erify both driving and driven sheaves are in alignment and

the shafts are parallel. The center line of the driving sheave must be in line with the center line of the driven sheave. See Figure 66.

2 Verify that all setscrews are torqued to the values shown in

Table 17, page 98 before starting drive. Check setscrew

torque and belt tension after 24 hours of service.

Figure 66: Sheave Alignment (Adjustable Shown)

M u s t b e p a r a l l e l

B e a r i n g

M o t o r

C e n t e r l i n e s m u s t c o i n c i d

The following should be performed as part of the air balancing procedure:

1 Check the operating balance with the economizer dampers

positioned for both full outdoor air and minimum outdoor air.

2 Verify that the total airflow will never be less than that

required for operation of the electric heaters or gas furnace.

M u s t b e p a r a l l e l

82 McQuay IM 791-2

A d j u s t a b l e S h e a v e

Check, Test, and Start Procedures

Drive Belt Adjustment

General Rules of Tensioning

1 The ideal tension is the lowest tension at which the belt will

not slip under peak load conditions.

2 Check tension frequently during the first 24-48 hours of

operation.

3 Over tensioning shortens belt and bearing life. 4 Keep belts free from foreign material which may cause

slippage.

5 Make V -drive inspection on a periodic basis. Adjust tension

if the belt is slipping. Do not apply belt dressing. This may damage the belt and cause early failure.

Tension Measurem ent Proc ed ure

1 Measure the belt span. See Figure 67. 2 Place belt tension checker squarely on one belt at the center

of the belt span. Apply force to the checker, perpendicular to the belt span, until the belt deflection equals belt span distance divided by 64. Determine force applied while in this position.

3 Compare this force to the values in on the drive kit label

found on the fan housing.

Mounting and Adjusting Motor Sheaves

Figure 68: VM and VP Variable Pitch Sheaves

S i n g l e G r o o v e

K e y " E " p r o j e c t s t o p r o v i d e a g r i p f o r r e m o v a l .

T w o G r o o v e

D o n o t o p e r a t e

s h e e v e s w i t h f l a n g e p r o j e c t i n g b e y o n d t h e h u b e n d .

Figure 67: Drive Belt Adjustment

D e f l e c t i o n =

B e l t S p a n

6 4

VM and VP Variable Pitch Sheaves

Mounting:

1 All sheaves should be mounted on the motor shaft with

setscrew “A” toward the motor (see Figure 68).

2 Be sure both the driving and driven sheaves are in

alignment and that the shafts are parallel.

3 Fit internal key “D” between sheave and shaft, and lock

setscrew “A” securely in place.

Adjusting:

1 Slack off all belt tension by moving the motor toward the

driven shaft until the belts are free from the grooves. For easiest adjustment, remove the belts.

2 Loosen setscrews “B” and “C” in the moving parts of the

sheave and pull out external key “E” (see Figure 68). This key projects a small amount to provide a grip for removing.

3 Adjust the sheave pitch diameter for the desired fan speed

by opening the moving parts by half or full turns from closed position. Do not open more than five full turns for

“A” belts or six full turns for “B” belts.

Adjust both halves of two-groove sheaves by the same number of turns from closed to ensure that both grooves have the same pitch diameter.

McQuay IM 791-2 83

Check, Test, and Start Procedures

4 Replace external key “E” and securely tighten setscrews

“B” over the key. Tighten setscrews “C” into the keyway in the fixed half of the sheave.

5 Put on belts and adjust the belt tension. Do not force belts

over grooves. Loosen the belts by adjusting the motor base

closer to the fan shaft.

6 Be sure that all keys are in place and that all setscrews are

tight before starting the drive. Check the setscrews and belt tension after 24 hours of service.

LVP Variable Pitch Sheaves

Mounting:

1 For single-groove sheaves, slide the sheave onto the motor

shaft so that the side of the sheave with setscrew “A” is next to the motor (see Figure 69, page 85). For two-groove sheaves, slide the sheave onto the motor shaft so that the side of the sheave with setscrew “A” is away from the motor (see Figure 69, page 85).

2 T o remove the flange and locking rings:

a Loosen setscrews “D”. b Loosen, but do not remove, capscrews “E”. c Remove key “F”. This key projects a small amount to

provide a grip for removing.

d Rotate the flange counterclockwise until it disengages

the threads on the shaft barrel.

3 Be sure that the driving and driven sheaves are in alignment

and the shafts are parallel. When aligning two-groove sheaves, allow room between the sheave and motor to get to capscrews “E”.

4 Insert key “C” between the sheave and the shaft and tighten

setscrew “A” securely.

Adjusting:

Slack off all belt tension by moving the motor toward the

driven shaft until the belts are free from the grooves. For easiest adjustment, remove the belts.

2 Loosen setscrews “D”. 3 Loosen, but do not remove, capscrews “E”. 4 Remove key “F”. This key projects a small amount to

provide a grip for removing.

5 Adjust the pitch diameter by opening or closing the

movable flange by half or full turns. Note that two-groove sheaves are supplied with both grooves set at the same pitch diameter. Both movable flanges must be moved the

same number of turns to ensure the same pitch

diameter for satisfactory operation. Do not open sheaves more than five turns for “A” belts or six turns for “B” belts.

6 Replace key “F”. 7 Tighten setscrews “D” and capscrews “E”. 8 Put on the belts and adjust the belt tension. Do not force

belts over grooves. Loosen the belts by adjusting the motor base closer to the fan shaft.

9 Be sure that all keys are in place and that all setscrews and

all capscrews are tight before starting the drive. Check and retighten all screws and retension the belts after approximately 24 hours of operation.

MVP Variable Pitch Sheaves

(Refer to Figure 69 and Figure 70) Adjusting:

Slack off belt tension by moving the motor toward the driven shaft until the belts are free from the grooves. For easiest adjustment, remove the belts.

2 Loosen both locking screws “A” in outer locking ring, but

do not remove them from the sheave. There is a gap of

approximately 0.2" (1 mm) between the inner and outer locking rings. This gap must be maintained for satisfactory locking of the sheave. If locking screws “A” are removed by accident and the gap is lost, screw the outer locking ring down until it touches the inner locking ring. Then back off the outer ring ½ to 3/4 turn until the inner and outer ring screw holes are lined up. Reinsert locking screws “A”, but do not tighten them until after adjustment is made.

3 Adjust the sheave to the desired pitch diameter by turning

the outer locking ring with a spanner wrench. Any pitch diameter can be obtained within the sheave range. One complete turn of the outer locking ring will result in a

0.233" (6 mm) change in pitch diameter.] Do not open “A-

B” sheaves more than 4-3/4 turns for “A” belts or 6 turns for “B” belts. Do not open “C” sheaves more than 9-1/2 turns.

4 Tighten both locking screws “A” in the outer locking ring. 5 Put on the belts and adjust the belt tension. Do not force

belts over grooves. Loosen the belts by adjusting the motor base closer to the fan shaft.

Important: Do not loosen any screws other than the two locking screws “A” in the outer locking ring. These screws

must be tightened securely before the drive is operated.

84 McQuay IM 791-2

Figure 69: LVP Variable Pitch Sleeves

Check, Test, and Start Procedures

S e c t i o n A - A S e c t i o n A - A

Figure 70: MVP Variable Pitch Sheaves (Type A-B)

C e n t e r F l a n g e s

G a p

O u t e r L o c k i n g R i n g

3 C a p s c r e w s " B "

Figure 71: MVP Variable Pitch Sheaves (Type C)

1 8 °

L o c k i n g

S c r e w s

" A "

I n n e r L o c k i n g R i n g

B a r r e l F l a n g e

B a r r e l

S p a n n e r W r e n c h H o l e

E n d F l a n g e

2 L o c k i n g

S c r e w s

" A "

T h r e a d

C e n t e r F l a n g e

A s s e m b l y

L o n g K e y

H e r e

S h o r t K e y

H e r e

McQuay IM 791-2 85

Rooftop Equipment Warranty Regist. Form

NOTE: This is a copy of the form included with the unit and may be used to make additional copies.

Rooftop Equipment Warranty Regist. Form

To comply with the terms of McQuay Warranty, complete and return this form within 10 days to McQuay, Warranty Department

Check, test, and start procedure for RoofPak roof mounted air conditioners with or without heat recovery and roof mounted air handlers.

Job Name: Installation address: __________________________________________________________________________________________________ City: ______________________________________________________________________________ State: __________________________ Purchasing contractor:________________________________________________________________________________________________ City: ______________________________________________________________________________ State: __________________________ Name of person doing start-up (print)____________________________________________________________________________________

Company name_____________________________________________________________________________________ Address ___________________________________________________________________________________________

City/State/Zip_______________________________________________________________________________________ Unit model number: ________________________________________________ Unit serial number:________________________________ Compressor 1 model number: ________________________________________ Serial number: ___________________________________ Compressor 2 model number: ________________________________________ Serial number: ___________________________________ Compressor 3 model number: ________________________________________ Serial number: ___________________________________ Compressor 4 model number: ________________________________________ Serial number: ___________________________________

Circle Yes or No. If not applicable to the type of unit, circle N/A.

I. INITIAL CHECK

A. Is any shipping damage visible? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Yes No N/A

B. Are fan drives properly aligned and belts properly adjusted? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Yes No N/A

C. Tightened all setscrews on pulleys, bearings and fans? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Yes No N/A

D. Have the hold-down bolts been backed off on spring mounted fan isolators?. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Yes No N/A

E. Do fans turn freely? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Yes No N/A

F. Has the discharge static pressure reference line been properly located within the building? Yes No N/A

G. Electrical service corresponds to unit nameplate?. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Yes No N/A

Volts Hertz Phase

H. Is the main disconnect adequately fused and are fuses installed? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Yes No N/A

I. Are crankcase heaters operating, and have they been operating 24 hours prior to start-up? . . . . . . . . . . . . . . . . . . . . Yes No N/A

J. Are all electrical power connections tigh t? (Check compressor electrical box.). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Yes No N/A

K. Is the condensate drain trapped?. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Yes No N/A

II. FAN DATA

A. Check rotation of supply fan?. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Yes No N/A

B. Voltage at supply fan motor: 1–2 _________V 2–3__________V 1–3 _________ V

C. Supply fan motor amp draw per phase: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . L1 L2 L3

D. Fuse sizes: ___________________________________________________________________

E. What is the supply fan rpm?

F. Check rotation of return fan? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Yes No N/A

G. Voltage at return fan motor: 1–2 _________V 2–3__________V 1–3 _________ V

H. Return fan motor amp draw per phase: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . L1 L2 L3

I. Fuse sizes: ___________________________________________________________________

J. What is the return fan rpm? K. Record supply static pressure at unit: ______________ inches of H20 L. Record return static pressure at unit (with outside air dampers closed)______________ inches of H20

III. START-UP COMPRESSOR OPERATION

A. Do compressors have holding charges?

Circuit #1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Yes No N/A

Circuit #2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Yes No N/A

B. Backseat discharge, suction (sizes 115 to 135C only), and liquid line valves? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Yes No N/A

C. Are compressors rotating in the right direction?. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Yes No N/A

D. Do condenser fans rotate in the right direction?. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Yes No N/A

McQuay G.O. No.:

86 McQuay IM 791-2

Rooftop Equipment Warranty Regist. Form

Warranty Registration Form (continued)

E. Ambient temperature ______________________ °F F. Oil safety control time delay (sizes 115 to 135C only): Compressor #1 ________ sec. Compressor #3 _______ sec.

Compressor #2________ sec. Compressor #4 ________sec.

G. Compressor lockout timers function?. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Yes No N/A

H. FanTrol functions: TC13 _________ TC14 ________

I. Part winding start time functions (sizes 115 to 135C option only):

Compressor: TD1 __________ TD2 __________ TD3__________ TD4__________ Supply fan: TD9 __________ Return fan: TD19 _________

J. Does unit start up and perform per sequence of operation? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Yes No N/A

IV. PERFORMANCE DATA

A. Compressor voltage across each phase: 1–2_________ V 2–3 _________ V 1–3 ________ V B. Compressor amperage of fully loaded compressor:

Compressor #1 Phase 1 _______ Phase 2________ Phase 3 ________ Compressor #2 Phase 1 _______ Phase 2________ Phase 3 ________ Compressor #3 Phase 1 _______ Phase 2________ Phase 3 ________ Compressor #4 Phase 1 _______ Phase 2________ Phase 3 ________

C. Low pressure cut-out: Circuit 1 __________ psig Circuit 2___________psig

Low pressure cut-in: Circuit 1 __________ psig Circuit 2 ___________psig

D. High pressure cut-out: Circuit 1 __________ psig Circuit 2 ___________psig

E. Discharge pressure, one compressor: Circuit 1___________ psig Circuit 2 __________ psig

Discharge pressure, fully loaded, 2–3 compressors: Circuit 1___________ psig Circuit 2 __________ psig

F. Suction pressure, one compressor: Circuit 1___________ psig Circuit 2 __________ psig

Suction pressure, fully loaded, 2–3 compressors: Circuit 1___________ psig Circuit 2 __________ psig Liquid press, fully loaded, 2–3 compressors

(at liquid line shutoff valve):

Liquid temperature, fully loaded, 2–3 compressors: Circuit 1___________ psig Circuit 2 __________ psig

G. System oil pressure (oil pressure-suction-net oil pressure):

(on four-compressor units, indicate for each compressor)

H. Suction line temperature: ___________ °F ____________°F

I. Superheat: ___________ °F ____________°F

J. Subcooling: ___________ °F ____________ °F

K. Is the liquid in the line sightglass clear and dry? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Yes No N/A

L. Does the hot gas bypass valve function properly?. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Yes No N/A

M. At what suction pressure does the hot gas bypass valve open? __________ psig __________ psig

N. Record discharge air temperature at discharge of unit: ____________°F

O. Are all control lines secure to prevent excessive vibration and wear?. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Yes No N/A

P. Are all gauges shut off and valve caps and packings tight after start-up?. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Yes No N/A

V. ELECTRIC HEAT CHECK, TEST & START

A. Electrical heat service corresponds to unit nameplate?. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Yes No N/A

Volts Hertz Phase

B. Are there any signs of physical damage to the electric heat coils? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Yes No N/A

C. Have all electrical terminals been tightened?. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Yes No N/A

D. Does sequence controller stage contactors properly? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Yes No N/A

E. Electric heater voltage across each phase: ____________L1 ____________L2 ___________ L3 F. Amp draw across each phase at each heating stage:

Stage 1 Stage 2 Stage 3 Stage 4 Stage 5 Stage 6 Phase L1: ___________ ___________ ____________ ____________ ___________ ___________ Phase L2: ___________ ___________ ____________ ____________ ___________ ___________ Phase L3 ___________ ___________ ____________ ____________ ___________ ___________

G. FLA: L1 ___________ L2 ___________ L3____________

H. Operate electric heat with fans off. Electric heat must cycle on high limit control.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . Yes No N/A

Circuit 1___________ psig Circuit 2 __________ psig

McQuay IM 791-2 87

Rooftop Equipment Warranty Regist. Form

Warranty Registration Form (continued)

VI. GAS & OIL BURNER CHECK, TEST, & START

Specifications: For gas, see Forced Draft Gas Burner Installation and Maintenance Bulletin. For oil, see Oil Fired Furnace Installation and Maintenance Bulletin.

A. (Gas/Oil) Furnace model no. __________________

B. (Gas/Oil) Burner model no. __________________ Serial no. ___________________ C. (Gas) Type firing: Single Stage two Stage modulation D. (Oil) Type firing start: Full fire start Low fire start

E. (Gas) Rated firing rate:_________________ MBH input

F. (Oil) Rated firing rate:_________________ GPH, #2 fuel oil G. (Gas/Oil) Altitude:___________________ ft. above sea level

H. Is there a circulating tank? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Yes No N/A

VII. GAS BURNER CHECK, TEST, & START

A. Input: _______________________________ CFH

B. Gas pressure at burner: _________________inches wc C. CO2: __________________________ % D. CO2: __________________________ %

E. Pilot flame only: _______________microamps (steady at low fire)

F. Pilot Tap-gas pressure:__________________ inches wc G. Motor only/burner: FLA__________________ running amps

H. High limit control OK?. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Yes No N/A

I. Flame safeguard: ________________ microamps

J. Flame failure shutoff: ________________ seconds

K. Airswitch OK?. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Yes No N/A

L. High Gas Pressure Switch OK? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Yes No N/A

M. Low Gas Pressure Switch OK? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Yes No N/A

N. Main Gas Valve Close-off OK?. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Yes No N/A

VIII. OIL BURNER CHECK, TEST & START

A. Nozzle(s): Type/manufacturer GPH Angle Pattern manufacturer B. Nozzle pressure: _______________________ psi

C. CO2: __________________________ % D. Smoke spot: number ______________

E. Running amps ________________ FLA F. Flame safeguard: microamps_________________

G. High limit control OK?. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Yes No N/A

H. Flame failure shutoff OK?. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Yes No N/A

I. Ignition failure check OK? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Yes No N/A

IX. Have all electronic or electrical controls been checked, adjusted, and tested for proper operation per the

installation and maintenance bulletins?

X. MAINTAINING MICROTECH CONTROL PARAMETER RECORDS

After the unit is checked, tested, and started and the final control parameters are set, record the final settings. Keep these records on file and update whenever changes to the control parameters are made. Keeping a record facilitates any required analysis and troubleshooting of the system operation and facilitates restoration after a controller replacement.

Yes No N/A

Signature:______________________________________________________ Startup date: ___________________________________

RETURN COMPLETED FORM TO:

McQuay International Warranty Department, 13600 Industrial Park Boulevard, Minneapolis, MN 55441 Please list any additional comments that could affect the operation of this unit; e.g., shipping damage, failed components, adverse installation applications, etc., on a separate sheet and attach to this form.

88 McQuay IM 791-2

Final Control Settings

When all start-up procedures have been completed, set the controls and program the MicroTech II controller for normal operation. Use the following list as a guide; some items may not apply to your unit. For more detail, refer to OM696.

1 Turn system switch S1 & S7 to “on.” 2 Turn gas furnace switch S3 to “auto” or turn electric heat

switch HS1 to “on.”

3 Turn compressor control switches CS1 and CS2 to “on.” 4 Turn liquid line solenoid switches PS1, PS2, and PS3 to

“on.”

5 Set the electromechanical (Honeywell H205) enthalpy

control (OAE) as required (A, B, C, or D). Set the solidstate (Honeywell H705/C7400) enthalpy control (OAE/ RAE) past “D”.

6 Set the heating and cooling parameters as required for

normal unit operation:

a Temperature \ Zone Cooling \ b Temperature \ Zone Heating \ c Temperature \ Discharge Cooling \ d Temperature \ Discharge Heating \

7 Set the low ambient compressor lockout setpoint as

required in menu, Temperature \ OA Damper \ OATComp Lock =. Do not set it below 50°F (10°C) unless the unit is

equipped for low ambient operation.

8 Set the high ambient heat lockout temperature setpoint,

Temperature \ Zone Heating \ OATHtg Lock = as required.

9 Set the alarm limits as required in

Setup/Service \ Alarm Limits \.

10 Set the compressor lead/lag function as desired using

keypad menu Setup/Service \ Compressor Setup \ Lead Circuit= and Setup/Service \ Compressor Setup \ CompCtrl=. Refer to “Compressor Staging” in Bulletins

OM 137 and OM 138. Note: If the unit has hot gas bypass on circuit #1 only, lead circuit must always be “#1”.

11 Set the duct static pressure control parameters as required

in keypad menu Airflow \ Duct Pressure \.

12 Set the building static pressure control paramet e rs as

required in keypad menu Airflow \ Bldg Pressure \.

13 Set the fan tracking parameters as required in keypad

menus Setup/Service \ Fan Tracking Setup \ and Setup/ Service \ Fan Balance \.

Final Control Settings

14 Set the economizer control parameters as required in

keypad menu Temperature \ OA Damper \.

15 Set the control timers as required in keypad menu

Setup/Service \ Timer Settings \.

16 Set the date and time in keypad menu

Setup/Service \ Time/Date \.

17 Set the operating schedule as required using keypad menus.

Note: When used with a Building Automation System,

these settings may need to be kept at the default of no schedule.:

Schedules \ Daily Schedule \

a b Schedules \ Holiday Schedule \

18 Place the unit into the Calibrate mode by using the keypad

menu Setup/Service \ Unit Configuration \ Calibrate Mode= and changing the value from “No” to “Yes”.

Calibrate will automatically zero all static pressure sensors and calibrate any actuator feedback pots connected to the MicroT ech II controller. When calibrate is finished, keypad menu System Summary \ System \ UnitStatus= will change from “Calib” to “Off Man”. To restart the unit change keypad menu System Summary \ System \ Ctrl Mode = from “Off” to “Auto”.

Maintaining Control Parameter Records

Record and save the MicroTech II controller's set points and parameters for future reference. If the Microprocessor Control Board ever requires replacement, this record will facilitate entering the unit's proper data. The following tables display all the set points, monitoring points, and pro gram variables offered by MicroT ech II plus the keypad road map used to find each parameter. All user adjusted set points and program variables are highlighted along with their default values.

Light gray boxes in Figure 72, page 90, Figure 73, page 91 &

Figure 74, page 92) indicate parameters specifically associated

with discharge air temperature control. Medium gray boxes in Figure 72, page 90, Figure 73, page 91

& Figure 74, page 92) indicate parameters specifically associated with space temperature control.

Dark gray boxes in Figure 72, page 90, Figure 73, page 91 &

Figure 74, page 92) indicate parameters common to both

control methods. Keep a record of any changes made to the shaded boxes.

McQuay IM 791-2 89

Final Control Settings

Figure 72: Keypad Accessible Menu Structure

Zone Cooling

Control Temp= xxx.x°F

CLEAR

ALARM

Move Display Down

Decrement Adjustable Parameter

Bldg Pressure

[15=1,2 or 4]

Bldg Press= x.xx"WC

ALARM

Move Display Up

Increment Adjustable Parameter

Display Active Alarm Clear Active Alarm

Duct Pressure

[14=1 or 2]

Duct Press= x.xx"WC

Clg Capacity= xxx%

BldgSP Spt= 0.050"WC

DuctSP Spt= 1.00"WC

Energy Recovery

[19=1 or 2]

RF/EF Fan Cap= xxx%

EF Min Cap= 5%

Energy Rec= Yes

ER DAT= xxx.x°F

Eff Clg Spt= xxx.x°F

Occ Clg Spt= 75.0°F

Clg Deadband= 2.0°F

CtrlTemp Src= Return

Space Temp= xxx.x°F

UnoccClg Spt= 85.0°F

UnoccClgDiff= 3.0°F

Clg Status= _____

OATClg Lock= 55°F

OATLock Diff= 1°F

Discharge Heating

Disch Air= xxx.x°F

BSP Db= 0.010"WC

DSP Db= 0.08"WC

RF/EF Fan Cap= xxx%

Disch Fan Cap= xxx%

RF/EF Fan Cap= xxx%

Evap Condensing

Htg Capacity= xxx%

[6>0]

VFD Speed= xxx%

Sump Temp= xxx.x°F

ER ExhT= xxx.x°F

Eff Htg Spt= xxx.x°F

DAT Htg Spt= 100.0°F

[1=1 or 3]

Htg Db= 2.0°F

Min Fan Speed= 25%

Min SumpT= 75°F

Max SumpT= 85°F

Min DAT Ctrl= Yes

Stage Time= 10 Min

Min Htg Spt= 60.0°F

Max Htg Spt= 120.0°F

Htg Reset= None

[1=1 or 3]

Min Htg Spt@= 0

[1=1 or 3]

Max Htg Spt@= 100

MinDAT Limit= 55.0°F

[1=0 or 2]

[1=1 or 3]

Keypad Key Definitions

Main Menu

System Summary

Move Display Right

Move Edit Cursor Right

Move Display Left

Move Edit Cursor Left

567

Airflow

Humidity

Schedules

Temperatures

SAVE

ENTER

Select Menu

BACK

CANCEL

Backup To Previous Menu

Active Alarms

Setup/Service

Previous Alarms

Save Edited Parameter

Airflow Summary

Flow Status= _____

Temperatures

Control Temp= xxx.x°F

Cancel Editing Command

Occupancy

Occupancy= _____

1 2 3

System

UnitStatus= _____AClg Capacity= xxx%

Disch Fan= _____

RF/EF Fan= _____

[15=0,1,2 or 4]

Fan Operation= _____

Disch Air= xxx.x°F

Return Air= xxx.x°F

[1=1 or 2]

Space Temp= xxx.x°F

Occ Mode= Auto

OccSrc= _____

Tnt Ovrd= 0 min

Htg Capacity= xxx%

Clg Status= _____

OA Temp= xxx.x°F

Ent Fan= xxx.x°F

Emerg Override= Norm

Htg Status= _____

Ctrl Mode= Off

[9=2,3,4,6,7,A or B]

Appl Mode= Heat/Cool

VAV Output= _____

[14=1 or 2]

Sub Menus

Max Signal= 100%

OA Damper

OA Damper Pos= xxx%

Discharge Cooling

Disch Air= xxx.x°F

Zone Heating

Control Temp= xxx.x°F

[7=3 or C]

MinOAResetMax= 50%

[7=1,2,3,4,A,B or C]

Eff Min OA Pos= xxx%

Clg Capacity= xxx%

Htg Capacity= xxx%

[7=3 or C]

Max Fan Diff= 50%

[7=3 or C]

OA Flow= xxxxxCFM

Eff Clg Spt= xxx.x°F

DAT Clg Spt= 55.0°F

Eff Htg Spt= xxx.x°F

Occ Htg Spt= 70.0°F

[15=1 or 2]

[8>0]

[1=1 or 3]

Min Fan Diff= 20%

OA Ambient= _____

Clg Db= 2.0°F

Htg Deadband= 2.0°F

[15=1 or 2]

Reset T Limit= 0°F

[7=3 or C]

EconChgovr= Enthalpy

[7=3 or C]

MinOA Type= None

[7=3 or C]

DesignFlow= No

Min Clg Spt= 55.0°F

Max Clg Spt= 65.0°F

CtrlTemp Src= Return

Space Temp= xxx.x°F

UnoccHtg Spt= 55.0°F

[7=3 or C]

EconChgovrT= 60°F

[7=3 or C]

[8>0]

MinOA Pos= 10%

[1=1,3,A or C]

Clg Reset= None

[1=1 or 3]

Min Clg Spt@= 0

UnoccHtgDiff= 3.0°F

Htg Status= _____

EconChgovrDiff= 1°F

[7=3 or C]

Max Purge= 60 min

[7=3 or C]

MinOA Flow= 2000CFM

[8>0]

MinOA @Max Sig= 60%

[7=3 or C]

[1=1 or 3]

Max Clg Spt@= 100

[1=1 or 3]

OATHtg Lock= 55°F

OATLock Diff= 1°F

OA Temp= xxx.x°F

Min Signal= 0%

[7=3 or C]

BACK

CANCEL

90 McQuay IM 791-2

Figure 73: Keypad Accessible Menu Structure (continued)

Final Control Settings

DF CapCtrl= DuctPres

Unit Configuration

AHU ID= _____

Optimal Start

Space Temp= xxx.x°F

[14=1 or 2]

Remote DF Cap= 25%

[14=1 or 2]

Comp Brd 1 ID= _____

[2=1]

Comp Brd 2 ID= _____

Optimal Start= No

Auto Update= Yes

RF/EF Ctrl= Tracking

[2=1, & 3<8]

Htg Rate= 0.4°F/min

[15=1,2 or 4]

Rem RF/EF Cap= 25%

[15=1,2 or 4]

GenCond Brd ID= ____

[3=8]

Htg OAT= 35°F

Eng Units= English

El Ht Brd ID= _____

[9=2]

Htg Zero OAT= 0°F

ER Brd ID= _____

[19=1 or 2]

Clg Rate= 0.4°F/min

Calibrate Mode= No

Clg OAT= 85°F

Clg Zero OAT= 100°F

Space Sensor= Yes

EFT Sensor= No

2nd P Sensor= None

[14=1,2 or 15=1,2 or 4]

Fan Balance

Fan Tracking

Duct Static P Setup

Time/Date

[14=1 or 2 & 15=1 or 2]

[14=1 or 2]

Fan Balance= Off

Set Max w/o Exh= No

Set Min w/o Exh= No

DF Max w/oExh= 100%

RF@DFMax w/oEx=95%

DF Min w/oExh= 20%

DSP Propbd= 6.0"WC

DSP IntTime= 40 sec

DSP Period= 10 sec

Time= hh:mm:ss

Day= day

Date= dd-mmm-yyyy

Set Max w/ Exh= No

Set Min w/ Exh= No

RF@DFMin w/oEx=15%

DF Max w/Exh= 100%

PRAC= No

Rem RF/EF Cap= 25%

RF@DFMax w/Ex=60%

DF Min w/Exh= 20%

RF@DFMin w/Ex=10%

DesignFlow Setup

[8>0]

Wait Time= 30 sec

Modband= 50%

Max Step= 5.0%

Deadband= 6.0%

LH Flow= xxx.xx%

RH Flow= xxx.xx%

AI11 Reference= No

Economizer Setup

[7=3 or C]

Clg Propbd= 30°F

Clg IntTime= 60 sec

Clg Period= 30 sec

Feedback= 3 Wire

Chilled Water Setup

[2=2 or A]

Clg Propbd= 30°F

Clg IntTime= 60 sec

Clg Period= 30 sec

Stage Time= 5 min

Feedback= 3 Wire

PRAC= No PRAC= No

Timer Settings

Service= 0 min

Recirculate= 3 min

[1=0 or 1]

Low DAT= 3 min

Max MWU= 90 min

[1=0 or 1]

Tnt Ovrd= 120 min

Start Init= 180 sec

Post Heat= 0 min

Holiday Schedule

Hol 1=mmmdd-mmmdd

Hol 2=mmmdd-mmmdd

Hol 3=mmmdd-mmmdd

One Event Schedule

Beg= mmm dd@hh:mm

End= mmm dd@hh:mm

5 6

Daily Schedule

Mon= 00:00 - 00:00

Tue= 00:00 - 00:00

Wed= 00:00 - 00:00

Thu= 00:00 - 00:00

Dehumidification

[1=0 or 2]

Dehum Status= _____

Rel Humidity= xxx%

Dew Point= xx.x°F

Dehum Method=None

Fri= 00:00 - 00:00

Sat= 00:00 - 00:00

RH Setpoint= 50%

Hol 13=mmmdd-mmmdd

Sun= 00:00 - 00:00

DewPoint Spt= 50°F

Hol 14=mmmdd-mmmdd

Hol 15=mmmdd-mmmdd

Hol= 00:00 - 00:00

DewPnt Db= 2°F

RH Db= 2%

Hol 16=mmmdd-mmmdd

Operating Hours

Passwords

Configuration Code

Fan= xxxxx hr

Mech Cool= xxxxx hr

Timeout= 15 min

Clear Alarm= No

Pos # 1-4= x.xxx

Pos # 5-8= x.xxx

[2>0]

Comp 1= xxxxx hr [2=1]

Comp 2= xxxxx hr [2=1]

Comp 3= xxxxx hr [2=1]

Pos # 9-12= x.xxx

Pos # 13-16= x.xxx

Pos # 17-20= x.xxx

[14=1 or 2]

Comp 4= xxxxx hr [2=1]

Pos # 21-22= x.x

Sub Menus (Continued)

Heating= xxxxx hr [9>0]

Economizer= xxxxx hr

[7=3 or C]

Tnt Ovrd= xxxxx hr

Comp 5= xxxxx hr [3=6]

Comp 6= xxxxx hr [3=6]

ERecovery= xxxxx hr

Compressor Setup

[2=1 & 3<8]

Lead Circuit= #1

Comp Ctrl= Cross Circ

Clg Method= Average

Cond Fan1 Spt= 0°F

Cond Fan2 Spt= 55°F

Cond Fan3 Spt= 65°F

Cond Fan4 Spt= 75°F

Cond Fan Diff= 5°F

Stage Time= 5 min

[19=1 or 2]

Zone Temp Setup

[1=0 or 2]

Exhaust Fan Setup

[15=4]

Bldg Static P Setup

[15=1,2 or 4]

Spt Source= Keypad

Min Exh Fan Cap= 25%

BSP Propbd= 1.0"WC

Clg Propbd= 8.0°F

Htg Propbd= 12.0°F

Min OA Dmpr= 5%

Min DF Cap= 10%

BSP IntTime= 10 sec

BSP Period= 5 sec

Clg IntTime= 700 sec

Period= 60 sec

Htg IntTime= 500 sec

Min Strt Time= 120 sec

Min Stop Time= 120 sec

PRAC= No

McQuay IM 791-2 91

Final Control Settings

Figure 74: Keypad Accessible Menu Structure (continued)

Comp #2 Alm= Slow

[3<8]

Comp #3 Alm= Slow

[3=4,5,6 or 7]

Comp #4 Alm= Slow

[3=5,6 or 7]

Comp #5 Alm= Slow

Freeze= Slow

[2=2,A or 9=1,5 or C]

OAT Sensor= Slow

Space Sensor= Slow

[1=0,1 or 3]

Alarm Out Problems

Return Sensor= Slow

[3=6]

[1=0 or 1]

Comp #6 Alm= Slow

Ent Fan Sens= Slow

[3=6]

[18=1]

Lo Airflow= Slow

PumpDown-Ckt1= Slow

[3<8]

PumpDown-Ckt2= Slow

[3<8]

Ckt1 Clg Ena= Slow

[3<8]

Ckt2 Clg Ena= Slow

[9=2,3,4,6,7,A or B]

Heat Fail= Slow

[9=3,4,6,A or B]

Fan Retry= Slow

[14=2]

Hi Press-Ckt1= Slow

[3<8]

GenC Clg Ena= Slow

[3=8]

HtgB Htg Ena= Slow

[9=2]

Ckt1 Comm Fail= Slow

Hi Press-Ckt2= Slow

[3<8]

Lo Press-Ckt1= Slow

[3<8]

Lo Press-Ckt2= Slow

[3<8]

Ckt2 Comm Fail= Slow

[3<8]

Frost-Ckt1= Slow

[3<8]

Genc Comm Fail= Slow

[3=8]

HtgB Comm Fail= Slow

[9=2]

ERecB CommFail= Slow

Frost-Ckt2= Slow

[3<8]

Comp #1 Alm= Slow

[3<8]

[19=1 or 2]

Previous Alarm 1

Alarm Name

Alarm Type

dd-mmm-yy hh:mm:ss

Active Alarm 4

Alarm Name

Alarm Type

dd-mmm-yy hh:mm:ss

Previous Alarm 8

Alarm Name

Alarm Type

dd-mmm-yy hh:mm:ss

Previous Alarm 7

Alarm Name

Alarm Type

dd-mmm-yy hh:mm:ss

Alarm Out Faults

Manual Control

Dehum Setup

[1=0 or 2]

Energy Recovery Setup

[19=1 or 2]

Freeze= Fast

[2=2,A or 9=1,5 or C]

Manual Control= No

Dehum Ctrl= Occupied

Min ExhT Diff= 2°F

Smoke= Fast

OAT Sensor= Fast

[1=3]

Discharge Fan= Off

RF/EF Fan= Off

[15=0,1,2 or 4]

Minimum Stages= 2

Maximum Stages= 4

Max ExhT Diff= 6°F

Stage Time= 5 min

Space Sensor= Fast

Fan Operation= Off

DH Stage Time= 10min

Min Off Time= 20 min

[1=2 or 3]

Return Sensor= Fast

Alarm= Normal

Sensor Loc= Return

Min Exh On= 120 sec

[1=0 or 1]

OA Damper= Auto

[7>0]

Min Exh Off= 120 sec

Disch Sensor= Fast

Mod Cooling= Auto

Duct Hi Limit= Fast

[14=1 or 2]

Hi Return Temp= Fast

[1=0 or 1]

Hi Disch Temp= Fast

[2=2 or A]

Mod Heating= Auto

[9=1,5 or C]

VAV Output= Heat

[14=1 or 2]

Disch Vanes= Auto

Lo Disch Temp= Fast

Fan Fail= Fast

OA Dmpr Stuck= Fast

[1=2 or 3]

[14=1]

RF/EF Vanes= Auto

[15=1]

Disch VFD= Auto

[14=2]

RF/EF VFD= Auto

Active Alarm 3

Alarm Name

Alarm Type

dd-mmm-yy hh:mm:ss

[15=2]

Active Alarm 2

Alarm Name

Alarm Type

dd-mmm-yy hh:mm:ss

7 8

Active Alarm 1

Alarm Name

Alarm Type

dd-mmm-yy hh:mm:ss

Alarm Limits

Hi Disch Alm= 170°F

Lo Disch Alm= 40°F

Hi Return Alm= 120°F

[1=1 or 3]

Previous Alarm 6

Alarm Name

Alarm Type

dd-mmm-yy hh:mm:ss

Previous Alarm 5

Alarm Name

Alarm Type

dd-mmm-yy hh:mm:ss

Previous Alarm 4

Alarm Name

Alarm Type

dd-mmm-yy hh:mm:ss

Previous Alarm 3

Alarm Name

Alarm Type

dd-mmm-yy hh:mm:ss

Heating Setup

Stage Time= 5 min

[9=2,3,4,6,7,A or B]

F&BP Ctrl= OpenValve

[9=1]

F&BP Chgovr= 37°F

[9=1]

Htg Propbd= 20°F

[9=1,3,4,5,A,B or C]

Htg IntTime= 120 sec

[9=1,3,4,5,A,B or C]

Htg Period= 60 sec

[9=1,3,4,5,A,B or C]

Feedback= 3 Wire

[9=3,4,5,A,B or C]

PRAC= No

[9=1,3,4,5,A,B or C]

Sub Menus (Continued)

Airflow Switch= Off

Alarm Out Warnings

Dirty Filter= Off

Dirty FnlFltr= Off [20=1]

Ckt1 H/W= Off [3<8]

Ckt2 H/W= Off [3<8]

GenC H/W= Off [3=8]

HtgB H/W= Off [9=2]

Previous Alarm 2

Alarm Name

Alarm Type

dd-mmm-yy hh:mm:ss

92 McQuay IM 791-2

Maintenance

CAUTION

Improper maintenance can cause severe personal injury or death.

Installation and maintenance must be performed only by trained, experienced personnel familiar with this type of equipment and local codes and regulations.

WARNING

Moving machinery and electrical power hazards. Can cause severe personal injury or death.

Lock out and tag out all power before servicing equipment.

CAUTION

Sharp edges are inherent to sheet metal parts, screws, clips, and similar items. Can cause personal injury.

Exercise caution when servicing equipment.

Planned Maintenance

Planned maintenance is the best way to avoid unnecessary expense and inconvenience. Have this system inspected at regular intervals by a qualified service technician. The required frequency of inspections depends upon the total operating time and the indoor and outdoor environmental conditions, but guidelines are provided in Table 9. Routine maintenance includes the following items:

Weekly

1 Clean or replace the filters as needed. Inspect every 40

hours under normal operation. More frequent inspection is required during construction periods or any other period that generates greater than normal filter loading

2 Check the water treatment system. Refer to IM 827 for

McQuay Chemical Free W ater T reatment System. For other treatment systems, follow the manufacturer’s recommendations. Generally, the following are required:

a Verify that chemical tanks have sufficient reserves. b Verify that chemical pumps are primed and functioning. c Confirm water hardness sensor is cleaned and

functioning.

d Inspect condenser tubes for evidence of scale buildup e Inspect for water leaks

3 During cooling season:

a Inspect the roof area for evidence of over spray. b Inspect the sump for buildup of mud and debris. Clean if

necessary. Refer to Sump Cleaning‚ page 95.

4 Check each circuit's refrigerant sightglass when the circuit

is operating under steady-state, full load conditions. The

sightglass should then be full and clear. If it is not, check for refrigerant leaks.

Note: A partially full sight glass is not uncommon at part

load conditions.

5 Check for blockage of the condensate drain. Clean the

condensate pan as needed.

6 Check the power and control voltages. 7 Check and adjust all temperature and pressure controls

as needed.

8 Examine the gas furnace (see Bulletin No. IM 684 or 685).

Monthly

1 During cooling season:

a Depress the low sump water float (WL64) to confirm

spray pump shutdown

b Depress sump water float (WL63) to confirm activation

of supply water solenoid valve SV61.

2 Check for proper superheat and subcooling (see Checking

Superheat‚ page 81 and Refrigerant Charge‚ page 99).

3 Check the running amperage of all motors. 4 Check all operating temperatures and pressures.

Bi-Monthly

1 Tighten, align, and replace any frayed belts. Tighten all

wire connections, and setscrews (Note: Belts must be checked for tightness after 24 hours of initial operation).

2 Clean the evaporator and condenser coils mechanically or

with cold water, if necessary. Usually any fouling is only matted on the entering air face of the coil and can be removed by brushing.

3 Lubricate the motor and fan shaft bearings. See page 96

(and page 73 for EAFs).

4 Check and adjust all damper linkages. 5 Check the operation of all safety controls. 6 Check the condenser fans and tighten their setscrews.

Annually

1 At the beginning of the cooling season, perform the

complete start up (see Check, Test, and Start Procedures‚

page 78).

2 At the end of the cooling season, shut down city water,

drain and clean the sump, verify that the spray pump is completely drained. If there is no heat in the service compartment, flush water piping with antifreeze and either drain the city water supply to a level below the roof, or confirm that any field supplied heat tape is functioning.

3 Lubricate the door latch mechanisms.

McQuay IM 791-2 93

Maintenance

Table 9: Maintenance Schedule

Maintenance Task Weekly Monthly Bi-Monthly Annually

Weekly Procedures

Clean or replace filters if necessary X X X X

Water treatment system - verify reserves in chemical tanks X X X X

Water treatment system - verify operation of chemical pumps X X X X

Water treatment system - verify operation of water hardness sensor and

clean residue if necessary

XX X X

Water treatment system - inspect condenser tubes for residue and clean

if necessary

Water treatment system - verify chemical tanks have reserves X X X X

Water treatment system - inspect for water leaks X X X X

Inspect roof area for evidence of over spray (during cooling season) X X X X

Inspect sump for residue and clean if necessary (during cooling season) X X X X

Inspect refrigerant sightglass and inspect for leaks if necessary X X X X

Inspect condensate drain pan for residue and clean if necessary X X X X

Inspect power and control voltages X X X X

Inspect all temperature and pressure controls. Adjust if necessary X X X X

Inspect gas furnace X X X X

Monthly Procedures

Depress low sump water float and confirm spray pump shutdown

(cooling season only)

Depress sump water float and confirm supply water solenoid valve

operation (cooling season only)

Inspect for proper superheat and subcooling X X X

Inspect running amperage of all motors X X X

Inspect all operating temperatures and pressures X X X

Bi-Monthly Procedures

Tighten/align belts or replace frayed belts X X

X X X X

XXX

X X X

Inspect evaporator/condenser coils for residue and clean if necessary X X

Lubricate motor and fan shaft bearings X X

Inspect all damper linkages and adjust if necessary X X

Inspect all safety controls and verify operation X X

Inspect condenser fans and tighten setscrews if necessary X X

Annual Procedures

Perform complete start up procedures (beginning of cooling season) X

Drain and clean the sump X

Verify any field supplied heat tape is functioning X

Lubricate all door latch mechanisms X

94 McQuay IM 791-2

Maintenance

Sump Cleaning

The spray operation washes articles out of the condenser air and condenser heat rejection evaporates water. The evaporation process leaves behind minerals and particles that settle in the sump and sump screen. The sump screen protects the pump and spray system and must be in place when the unit is operating. To clean the sump (see Figure 75):

1 Drain the Sump by opening the manual Drain Valve and

pumping as much water as possible into a sanitary sewer.Gravity

2 Gravity drain the remaining water into containers and

dispose of properly.

3 Remove the Sump Screen and clean. 4 A Hose Bib and Shut Off Valve is provided inside the

service compartment. See Figure 6, page 9. Use a hose to wash any remaining sediment out of the drain.

Figure 75: Cleaning the Sump

5 Provide unit doors are securely closed and locked. 6 If isolation dampers are provided, verify that they are

properly installed and fully closed to prevent the entry of animals and debris through the supply and return air openings.

7 Units without isolation dampers should be fitted with

covers over the supply and return air openings.

Preparation

Supply (and Return) fans

1 Move the motor base to check and lubricate slides and

leadscrews.

2 Remove the drive belts, tag them with the fan name and

unit serial number and store them in a conditioned space out of direct sunlight.

3 Turn the supply and return fan manual motor protectors

(MMPs) to the off position.

4 Once every month, rotate the fan and motor shafts. Mark

the shaft positions fIrst to make sure they stop in a different position.

5 Depending on local climatic conditions, condensate can

collect on components inside the units. To prevent surface rust and discoloration, spray all bare metal parts with a rust preventive compound. Pay close attention to fan shafts, sheaves, bearings and bearing supports,

Manua

Removable

Screen

Sum

Drain Valve

Unit Storage

Location

The McQuay Rooftop Packaged System Unit is an outdoor unit. However, the schedule may dictate storage either on the ground or in its final position at the site. If the unit is stored on the ground, additional precautions should be taken as follows:

1 Make sure that the unit is well supported along the length

of the base rail.

2 Make sure that the unit is level

(no twists or uneven ground surface).

3 Provide proper drainage around the unit to prevent flooding

of the equipment

4 Provide adequate protection from vandalism, mechanical

contact, etc. The condenser fins are particularly vulnerable to damage by even light contact with ground based objects.

Cabinet Sections

1 Once a month, open a door on each section and verify that

no moisture or debris is accumulating in the unit.

Cooling circuits

1 Provide that each circuit is properly pumped down. 2 Pull the fuses to each compressor

(store them in the control cabinet)

3 Close all the refrigerant service valves on each circuit 4 Tag the valves as a warning for the technici an who will be

restarting the units

5 Note: steps 1 to 4 are not necessary if the unit had not yet

been started.

Gas Furnace

If the unit is equipped with a gas furnace, close the gas shutoff valve and open furnace control switch S3.

Control Compartment

McQuay International recommends that the electronic

control equipment in the unit be stored in a 5% to 95% RH (non-condensing) environment.

2 It may be necessary to put a heat source (light bulb) in the

main control panel to prevent the accumulation of atmospheric condensate within the panel.

McQuay IM 791-2 95

Maintenance

3 The location and wattage of the heat source will be

dependent on local environmental conditions.

4 Check the control compartment every two weeks to provide

that the heat source is functional and is adequate for current conditions.

Restart

After extended storage, a very complete start up must be performed. Inevitable accumulations of dirt, insect nests, etc. can contribute to problems if not cleaned out thoroughly prior to start up. In addition, thermal cycling will have tended to loosen mechanical and electrical connections. Following the start up procedure will help discover these and other issues that may have developed during the storage interval.

Gas Furnace

For information on maintenance of the gas furnace, refer to Bulletin No. IM 684 or 685.

Bearing Lubrication

CAUTION

Bearing overheating potential. Can cause damage to the equipment. Do not overlubricate bearings. Use only a high grade mineral grease with a 200°F safe operating temperature. Refer to the list below for recommended lubricant types.

Motor Bearings

Supply and Return Fans—Supply and return fan motors should have grease added after every 2000 hours of operation. Use one of the greases shown below. using the following procedure, lubricate the bearings while the motor is warm, but not running.

1 Remove and clean the upper and lower grease plugs. 2 Insert a grease fitting into the upper hole and add clean

grease according to the grease charge shown in Table 10 with a low pressure grease gun.

3 Run the motor for 6 minutes before replacing the plugs. Note: Specific greasing instructions may be located on a tag

attached to the motor. If specific lubrication instructions

are on the motor, they supersede all other instructions.

Condenser fan - Condenser fan motors are permanently lubricated and require no periodic lubrication.

Recommended grease to be used for motor bearings:

• Polyrex EM (Exxon Mobile)

• Texaco Polystar

• Rykon Premium #2

• Penzoil Pen 2 Lube

• Chevron SRI

Table 10: SAF, RAF, & EAF Motor Relubrication Grease Charge

NEMA Frame

Size

56 to 140 0.08

140 0.15 180 0.19 210 0.3 250 0.47 280 0.61 320 0.76 360 0.81 400 1.25 440 2.12

Bearing Grease

Charge (oz)

Fan Shaft Bearings

Compatibility of grease is critical. Relubricatable Browning bearings are supplied with grease fittings or zerks for ease of lubrication with hand or automatic grease guns. Always wipe the fitting and grease nozzle clean.

CAUTION

For safety, stop rotating equipment. Add one half of the recommended amount shown in Table 10. Start bearing, and run for a few minutes. Stop bearing and add the second half of the recommended amount. A temperature rise, sometimes 30°F (1°C), after relubrication is normal. Bearing should operate at temperature less than 200°F (94°C) and should not exceed 225°F (107°C) for intermittent operation. For a relubrication schedule, see Table 11. For any applications that are not in the ranges of the table, contact McQuay.

CAUTION

The tables below state general lubrication recommendations based on our experience and are intended as suggested or starting points only. For best results, specific applications should be monitored regularly and lubrication intervals and amounts adjusted accordingly.

Table 11: SAF and RAF Relubrication Intervals

(Use NLGI #2 Lithium or Lithium Complex Grease)

Speed Temperature Cleanliness Relub. intervals

100 rpm

500 rpm

1000 rpm

1500 rpm

Above 1500 rpm

Max catalog rating

Up to

120°F

(50°C)

Up to

150°F

(65°C)

Up to

210°F

(100°C)

210°F

Over

(100°C) to

250°F (120°C)

Up to

150°F

(65°C)

150°F

Over

(65°C) to 250°F

(120°C)

Above

250°F

(120°C)

Clean 6 to 12 months

Clean 2 to 6 months

Clean

Clean Weekly

Dirty/wet 1 seek to 1 month

Dirty/wet Daily to 2 weeks

2 weeks to 2

months

Contact Browning

96 McQuay IM 791-2

Maintenance

Table 12: SAF and RAF Recommended Relubrication Grease Charge

Shaft Size (in) OZ. Shaft Size Grams

1/2 to 3/4 0.03 20 mm 0.85

7/8 to 1-3/16 0.10 25-30 mm 2.84

1-1/4 to 1-1/2 0.15 35-40 mm 4.25

1-11/1 6 to 1-15/16 0.20 45-50 mm 5.67

2 to 2-7/16 0.30 55-60 mm 8.51

2-1/2 to 2-15/16 0.50 65-70 mm 15.59

3 to 3-7/16 0.85 75-80 mm 24.10

3-1/2 to 4 1.50 85-105 mm 42.53

Table 13: Recommended lubricants for fan shaft bearings

Product Name

Texaco Premium RB-30 to 350ºF

Mobile AW2

Mobile SCH 100 Chevron Altiplex

Synthetic

Exxon Ronex MP

Note: Temperature ranges over 140ºF are shown for lubricants only.

Maximum unit temperature is 140ºF.

Temperature

Range

-34 to 177ºC

-40 to 437ºF

-40 to 175ºC

-58 to 356ºF

-50 to 180ºC

-60 to 450ºF

-51 to 232ºC

-40 to 300ºF

-40 to 149ºC

Base Thickener

paraffinic

mineral oil Mineral oil Lithium 2

Synthetic Lithium 2

Mineral oil Lithium 2

Lithium 2

NLGI

Grade

CAUTION

Failure to observe safety precautions can cause personal injury or equipment damage.

CAUTION

Failure to carefully follow installation instructions can result in improper installation, which can cause bearing performance problems as well as derious personal injury. Before attempting to install or remove bearings, read installation/removal instructions in their entirety.

Bearing Replacement

The following instructions must be read in entirety before attempting installation or removal. The procedures indicated should be carefully followed. Failure to do so can result in improper installation which could cause bearing performance problems as well as serious personal injury.

Bearings in Bolt-On Housings (Units)

1 Check area - Clean and organize bearing installation area

and keep well lit. Be sure mounting surfaces are clean and flat.

2 Check shaft - Shaft should be within tolerance range shown

in Table 14, clean, and free of nicks and burrs. Mount bearing on unused section of shafting or repair/replace

shafting as required.

Table 14: Shaft Size To lerances

Shaft Size (in) Tolerance

1-11/16 to 2-7/16 +0 to -0.0015

2-7/16 and up +0 to -0.002

3 Install unit - Slide unit onto shaft. If it is difficult to mount

bearing on shaft, use a piece of emery cloth to reduce any high spots on shaft. Do not hammer on any component of the bearing.

4 Fasten unit in place - Install housing mounting bolts, check

and align bearing and tighten mounting bolts to recommended fastener torques. Exercising extreme caution and safety, rotate shaft slowly to center bearing.

BOA Concentric Inserts

1 Be sure that BOA Concentric collar is fitted square and

snug against the shoulder on the inner ring.

2 Torque BOA Concentric collar cap screw to torque

recommended in Table 15.

Table 15: Recommended Torque Values for Concentric Locking Bearing/Shaft Size

Fan Size (in) Bore Size (in)

27 (AF)/40 & 49

(SWSI)

30 & 33 (AF)/44

(SWSI)

36 (AF 2-11/16 T-45 400

40 (AF) 2-15/16 T-45 400

2-3/16 T-30 180

2-7/16 T-45 400

Torx Screw

Size

In lbs.

Note: AF = DWDI AF, SWSI = AF Plenum Fan

Monitor Installed Bearing

After bearing has been run for several minutes, and again after several hours, check bearing for excessive noise or vibration. Shutdown machine and check housing temperature: typical applications operate at 100°F - 105°F (38°C - 66°C). Tighten all locking devices after 500 hours or 3 months, whichever comes first.

Vibration Levels

Each unit as shipped has been trim-balanced to operate smoothly. To provide satisfactory operation after shipping and installation, use the accepted industry guidelines for field balancing fans. See Table 16.

Table 16: Vibration Levels

FAN SPEED (RPM) VIBRATION

800 or less 5 mils maximum displacement

801 or greater 0.20 in/sec. maximum velocity

Note: Excessive vibration from any cause contributes to premature fan and motor bearing failure. Overall vibration levels should be monitored every six months of operation. An increase in levels is an indication of potential trouble.

Vibration Causes

1 Wheel imbalance.

a Dirt or debris on wheel blades. b Loose setscrews in wheel hub or bearing-to-shaft.

c Wheel distorted from overspeed. 2 Bent shaft. 3 Drive faulty.

McQuay IM 791-2 97

Maintenance

a Variable pitch sheaves - Axial and radial runout of

flanges; uneven groove spacing; out of balance. Also similar faults in driven sheave.

b Bad V-belts; lumpy, or mismatched; belt ten sion too

tight or too loose.

4 Bad bearings, loose bearing hold-down bolts. 5 Motor imbalance. 6 Fan section not supported evenly on foundation.

Periodic Service and Maintenance

1 Check all moving parts for wear every six months. 2 Check bearing collar, sheave, and wheel hub setscrews,

sheave capscrews, and bearing hold-down bolts for tightness every six months.

Setscrews

Setscrews lock bearings, sheaves, locking collars and fan wheel to their shafts. It is very important that all setscrews be checked periodically to provide that they have not loosened. If

this is not done, severe equipment damage could occur.

CAUTION

Improperly tightened setscrews can lead to severe equipment damage.

Using Table 17 and Table 18, check the tightness of all setscrews with a torque wrench. Note that if the return fan bearing setscrews need to be retightened, a special procedure is required to equally load both bearings (see Return Fan Bearing

Setscrews‚ page 98).

If a setscrew is checked for proper torque and is found to be below the minimum torque or is loose or has been removed, it is a good indication that the assembly conditions have changed. Do not attempt to reuse a setscrew in this case. (Setscrews have special points designed to cut into the shaft material to create the clamping force. Use of the proper torque will always cause deformation of this point. Reusing a setscrew with a deformed point will give an unknown clamping force for a given torque.)

Before installing a new setscrew, clean out the threads in the hole. Apply one drop of light machine oil to the threads of the setscrew prior to installation. Excess oil or any grease will compromise the clamping pressure that is required for proper installation. Do not use oil with EP (extreme pressure) additive. Do not use liquid chemical thread sealant such as Loctite since it may foul the threads and give improper torque settings.

Table 17: Screw Torque Settings, Socket Head for Bearings

Socket Head for

bearings Dia. (in.) Low (ft-lb.) High (ft-lb.)

1/4 5.0 6.5

5/16 12 14

3/8 20 25

7/16 30 38

3/4 50 52 5/8 91 94

Table 18: Screw Torque Settings, Square Head for Fan Hubs

Square Head for fan

hubs (across flats)

Dia. (in.) Low (ft-lb.) High (ft-lb.)

3/8 23 30 3/4 60 75 5/8 125 150

Diamond Faceted and knurled point setscrews

Cup Point setscrews

Return Fan Bearing Setscrews

Because the return fan Is mounted on a vertical shaft, the following procedure must be used to retighten any return fan bearing setscrews that have loosened. This procedure will provide that both bearings are equally loaded. If one bearing is carrying the entire weight of the fan, it could fail prematurely.

1 Loosen the fan belts. 2 Support the weight of the fan and the fan shaft with timbers

or some other suitable means (see Figure 76). Important: In order to maintain proper drive alignment and fan-to-tunnel clearance, the fan and shaft must not drop at all when the setscrews are loosened in Step 4.

3 Verify that the upper shaft collar is securely fastened to the

shaft. Check the setscrew torque.

4 Loosen the upper and lower bearing setscrews. The entire

weight of the fan and shaft is now supported by the fan shaft support.

5 Retighten all bearings to the torque specification given in

Table 17.

6 Remove the fan shaft support and retension the belts.

Figure 76: Return Fan Assembly

Upper

Bearing

Fan

Wheel

Fan

Shaft

Fan Shaft

Support

98 McQuay IM 791-2

Lower

Bearing

Maintenance

Supply Fan Wheel-to-Funnel Alignment

If the unit is equipped with an airfoil or backward curved supply fan, the fan wheel-to-funnel alignment must be as shown in Figure 77, Figure 78 and Figure 79, page 99 to obtain proper air delivery and operating clearance. If necessary , adjustments are made as follows:

1 Verify that the fan shaft has not moved in its bearings. 2 Loosen the fan hub setscrews and move the wheel(s) along

the shaft as necessary to obtain the correct dimension shown in Table 19, Table 20, and Table 21, page 99.

3 Retighten the setscrews to the torque specification given in

Table 17, page 98. Tighten the setscrews over the keyway

first; tighten those at 90 degrees to the keyway last.

4 Verify that the radial clearance around the fan is uniform.

Radial clearance can be adjusted by slightly loosening the funnel hold-down fasteners, shifting the funnel as required, and retightening the fasteners.

Figure 77: 27"-33" Airfoil Wheel-to-Funnel Alignment

Figure 79: 44" Airfoil Wheel-to-Funnel Alignment

W h e e l

F u n n e l

Table 21: 44" Airfoil Wheel-to-Funnel Tolerances (RDT 045 - 075)

WHEEL-TO-FUNNEL RELATIONSHIP

WHEEL DIA. (IN.)

44 16.21

“A” (IN INCHES)

Refrigerant Charge

The unit nameplate references proper charge for each refrigerant circuit in case a full charge must be added to the

unit.

WARNING

Abrupt loss of charge can cause severe personal injury.

Reclaim refrigerant before replacing.

Table 19: Airfoil Wheel-to-Funnel Tolerances

Wheel-to-Funnel Relationship (In Inches)

Wheel Diameter Inches) “A” +0.3/ —0.0

Figure 78: 40" Airfoil Wheel-to-Funnel Alignment (RDT 045 - 075)

Table 20: 40"Airfoil Wheel-to-Funnel Tolerances (RDT 045 - 075)

27 9.90 (246mm) 30 10.60 (269mm) 33 11.70 (297mm)

W h e e l

F u n n e l

WHEEL-TO-FUNNEL RELATIONSHIP

WHEEL DIA. (IN.) “A” (IN INCHES)

Take special care to add refrigerant slowly enough to the suction to prevent damage. Adjust the charging tank hand valve so liquid leaves the tank but vapor enters the compressor.

This is especially true with R-407C because the charge must be drawn from the liquid portion of the tank.

CAUTION

Units purchased for R-22 operation must be charged only with R-22. Units purchased for R-407C operation must be charged only with R-407C.

Field mixing or changing of refrigerants can compromise performance and damage equipment.

Table 22: Acceptable Refrigerant Oils

Polyolester [POE] oils

Note: Do not use mineral oils

Copeland ULtra 22 CC

Mobil EAL™ Arctic 22 CC

ICI EMKARATE RL™ 32CL

Subcooling

When field charging the unit, use the following to properly charge the unit:

• All compressors on each circuit operating at full capacity.

• Allowable subcooling ranges are between 13°F to 20°F.

• Be sure to measure pressure and temperature at the same

location when finding/calculating subcooling. Compare the actual temperature and pressures to the saturated liquid temperature. R-407C example: A pressure of 250 psi is

McQuay IM 791-2 99

Maintenance

measured at the condenser outlet. From the R-407C chart, 250 psig is approximately 108°F saturated liquid temperature. If the actual refrigerant temperature is 98°F , the liquid is subcooled 10°F.

• Ambient temperature must be between 60°F and 105°F.

• Hot Gas Bypass NOT operating (only if unit is supplied with

option).

If any one of the above items is not followed, subcooling readings will not be accurate and the potential exists for over or undercharging of the refrigerant circuit.

Refrigerant Charging with Zeotropes

R-407C is a zeotropic mixture. During initial charging or “topping” off a system, it is important to remove the refrigerant from the charging cylinder in the liquid phase. Many of the cylinders for the newer refrigerants use a dip tube so that in the upright position liquid is drawn from the cylinder. DO NOT vapor charge out of a cylinder unless the entire cylinder is to be charged into the system. Refer to charging instructions provided by the refrigerant manufacturer.

Replacing Failed Refrigerant Sensors or Switches

Evaporative Condenser Section

Nozzle and Spray Tree Removal

Remove Outer Trim Panels

1 Remove outer trim panels

The McQuay Rooftop Unit includes the following refrigerant sensors or switches.

1 Low refrigerant sensing, operating switch 2 High refrigerant pressure, safety switch

The low pressure and Speedtrol sensors/ switches sense refrigerant pressure through schrader fittings that contain cores. The cores are stop valves that will not allow refrigerant to flow through the schrader unless the device is in place. Therefore the low pressure and Speedtrol sensors/switches can be replaced without reclaiming the refrigerant.

The schrader that serves the high pressure switch does not contain a core, in order to maximize the functionality of the safety. Therefore it cannot be replaced unless the refrigerant has already been reclaimed.

Unthread Spray Tree Assembly by Holding Spray Nozzle Tee and Rotating Counter-clockwise

Rotate Assembly so Nozzle T ees will slip through Support Brackets and pull asembly out.

2 Disconnect either or both spray trees from the 2" PVC

bushing at the rear manifold by rotating the tree assembly counter-clockwise.

3 After tree assembly is disconnected, rotate it so the nozzles

are horizontal and pull assembly out.

100 McQuay IM 791-2

McQuay RDE076C Installation Manual

Specifications and Main Features

Frequently Asked Questions

User Manual

Introduction

Unit Nameplate

Gas Burner Nameplate

Hazard Identification Information

Nomenclature

Unit Description

Condenser Fan Arrangement

Refrigerant Circuit Schematic

Refrigeration Piping

Spray System Plumbing with Optional Non-Chemical Water Treatment

Bleed Off and Water Consumption

Control Locations

Walk-In Service Compartment

Mechanical Installation

Receiving Inspection

Unit Clearances

V entilation Clearance

Overhead clearance

Roof Curb Assembly and Installation

Reassembly of Split Units

Condensate Drain Connection

Unit Piping

Steam Piping Recommendations

Steam Coil Piping

Steam Trap Recommendations

Damper Assemblies

Cabinet Weatherproofing

Installing Ductwork

Installing Duct Static Pressure Sensor Taps

Electrical Installation

Field Power Wiring

Field Control Wiring

Preparing Unit for Operation

Relief Damper Tie-Down

Spring Isolated Fans

Adjusting Spring Mounts

Spring Isolated Compressors

Sequences of Operation

Power-up

Fan Operation

Economizer Operation

Heating

Wiring Diagrams

Legend

Typical Control Schematic: Discharge Air Control (DAC)

Typical Control Schematic: Zone or Space Comfort Control (SCC)

Typical Output Schematic: Actuator Control

Typical Schematic: Condenser Fan, Anti-Corrosion Electric Heaters

Typical Output Schematic: VFD Control (SAF/RAF)

Typical Output Schematic: VFD Control Continued (SAF/RAF)

Typical Power Circuit Wiring - 4 Compressor - VFD

Typical Condensing Unit Control - MicroTech II - 4 Compressor

Typical Super Mod Gas Furnace Control (1000 MBh)

Unit Options

Non-Chemical Water Treatment

Enthalpy Control

Hot Gas Bypass

External Time Clock

Smoke Detectors

Freeze Protection

Low Airflow Alarm

Duct High Pressure Limit

Condensing Unit VFD Operation

V a riable Frequency Drive Operation

Convenience Receptacle/Section Lights

DesignFlow™ Outdoor Air Damper Option

Propeller Exhaust Fan Option

Propeller Exhaust Fan Control

Ultraviolet Lights Option

Ultraviolet Light Operation

Check, Test, and Start Procedures

Before Start-Up

Power-Up

Fan Start-Up

Economizer Start-Up

Evaporative Condenser Start-Up