McQuay RAH 047C, RAH 077C, RDS 800C, RDS 802C Maintenance Manual

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Installation and Maintenance Manual IM 987

RoofPak™ Applied Rooftop Systems Air Handler

RAH 047C - 077C, 12,000 to 50,000 cfm RDS 800C - 802C, 4000 to 20,000 cfm with MicroTech® III Unit Controller

Group: Applied Air Systems

Part Number: IM 987

Date: May 2009

Contents

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

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

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

Typical Component Locations. . . . . . . . . . . . . 4

Control Locations . . . . . . . . . . . . . . . . . . . . . . 4

Control Panel . . . . . . . . . . . . . . . . . . . . . . . . . 5

Controls, Settings, and Functions . . . . . . . . . 12

Mechanical Installation . . . . . . . . . . . . . . . . . . . . . 14

Unit Clearances. . . . . . . . . . . . . . . . . . . . . . . 14

Ventilation Clearance . . . . . . . . . . . . . . . . . . 15

Overhead Clearance . . . . . . . . . . . . . . . . . . . 15

IBC Seismic Compliant Units . . . . . . . . . . . . 20

Roof Curb Arrangement . . . . . . . . . . . . . . . . 20

Post and Rail Arrangement . . . . . . . . . . . . . . 22

Post and Rail Mounting . . . . . . . . . . . . . . . . . 24

Rigging and Handling . . . . . . . . . . . . . . . . . . 24

Split Units . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Unit Piping. . . . . . . . . . . . . . . . . . . . . . . . . . . 31

Steam Coil Piping (All Units) . . . . . . . . . . . . . 33

Steam Piping Recommendations . . . . . . . . . 33

Steam Trap Recommendations . . . . . . . . . . 34

Vestibule Assembly Instructions . . . . . . . . . . 38

Damper Assemblies . . . . . . . . . . . . . . . . . . . 40

Cabinet Weather Protection . . . . . . . . . . . . . 44

Installing Ductwork . . . . . . . . . . . . . . . . . . . . 45

Installing Duct Static Pressure Sensor Taps. 46 Installing Building Static Pressure

Sensor Taps . . . . . . . . . . . . . . . . . . . . . . . . . 47

Electrical Installation . . . . . . . . . . . . . . . . . . . . . . 48

Field Power Wiring . . . . . . . . . . . . . . . . . . . . 48

Field Control Wiring. . . . . . . . . . . . . . . . . . . . 51

Mechanical Installation . . . . . . . . . . . . . . . . . . . . . 52

Preparing Unit for Operation . . . . . . . . . . . . . 52

Spring Isolated Fans . . . . . . . . . . . . . . . . . . . 52

Relief Damper Tie-Down. . . . . . . . . . . . . . . . 53

Adjusting Scroll Dampers . . . . . . . . . . . . . . . 53

Adjusting Supply Fan Thrust Restraints . . . . 53

Adjusting Seismic Restraints. . . . . . . . . . . . . 54

Sequences of Operation . . . . . . . . . . . . . . . . . . . . 55

Power-up. . . . . . . . . . . . . . . . . . . . . . . . . . . . 55

Fan Operation . . . . . . . . . . . . . . . . . . . . . . . . 55

Economizer Operation . . . . . . . . . . . . . . . . . 56

Heating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

MicroTech III Controller Operation . . . . . . . . . . . 57

Using the Keypad/Display . . . . . . . . . . . . . . . 57

Passwords. . . . . . . . . . . . . . . . . . . . . . . . . . . 57

Navigation Mode . . . . . . . . . . . . . . . . . . . . . . 58

Edit Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . 58

Wiring Diagrams . . . . . . . . . . . . . . . . . . . . . . . . . . 59

Legend . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59

Unit Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84

Control Actuators . . . . . . . . . . . . . . . . . . . . . 84

Enthalpy Control . . . . . . . . . . . . . . . . . . . . . . 84

External Time Clock . . . . . . . . . . . . . . . . . . . 85

Smoke and Fire Protection . . . . . . . . . . . . . . 85

Smoke Detectors . . . . . . . . . . . . . . . . . . . . . 85

Emergency Shutdown . . . . . . . . . . . . . . . . . 86

Freeze Protection . . . . . . . . . . . . . . . . . . . . . 86

Field Output Signals . . . . . . . . . . . . . . . . . . . 87

Entering Fan Temperature Sensor . . . . . . . . 87

Duct High Pressure Limit . . . . . . . . . . . . . . . 88

Variable Frequency Drive Operation . . . . . . 88

Convenience Receptacle/Section Lights . . . 88 DesignFlow™ Outdoor Air Damper Option . 88

Propeller Exhaust Fan Option . . . . . . . . . . . 91

Exhaust Fan On/Off Control . . . . . . . . . . . . . 93

Ultraviolet Lights Option . . . . . . . . . . . . . . . . 94

Ultraviolet Light Operation . . . . . . . . . . . . . . 95

Check, Test, and Start Procedures . . . . . . . . . . . 96

Servicing Control Panel Components. . . . . . 96

Before Start-up . . . . . . . . . . . . . . . . . . . . . . . 96

Power Up . . . . . . . . . . . . . . . . . . . . . . . . . . . 96

Fan Start-up . . . . . . . . . . . . . . . . . . . . . . . . . 97

Economizer Start-up. . . . . . . . . . . . . . . . . . . 97

Heating System Startup . . . . . . . . . . . . . . . . 98

Air Balancing . . . . . . . . . . . . . . . . . . . . . . . . 98

Sheave Alignment . . . . . . . . . . . . . . . . . . . . 99

Drive Belt Adjustment . . . . . . . . . . . . . . . . . . 99

Mounting and Adjusting Motor Sheaves. . . 100

Final Control Settings. . . . . . . . . . . . . . . . . . . . . 103

Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106

Servicing Control Panel Components. . . . . 106

Planned Maintenance. . . . . . . . . . . . . . . . . 106

Unit Storage . . . . . . . . . . . . . . . . . . . . . . . . 106

Gas Furnace. . . . . . . . . . . . . . . . . . . . . . . . 107

Bearing Lubrication. . . . . . . . . . . . . . . . . . . 107

Setscrews . . . . . . . . . . . . . . . . . . . . . . . . . . 109

Supply Fan Wheel-to-Funnel Alignment. . . 110

Winterizing Water Coils . . . . . . . . . . . . . . . 111

Control Panel Components . . . . . . . . . . . . 111

Replacement Parts List . . . . . . . . . . . . . . . . . . . 115

Replacement Parts . . . . . . . . . . . . . . . . . . . 115

Service and Warranty Procedure . . . . . . . . . . . 116

In-Warranty Return Material Procedure . . . 116

Limited Product Warranty (North America) . . . 117

Exceptions . . . . . . . . . . . . . . . . . . . . . . . . . 117

Assistance . . . . . . . . . . . . . . . . . . . . . . . . . 117

Sole Remedy . . . . . . . . . . . . . . . . . . . . . . . 117

Rooftop Equipment Warranty Regist. Form. . . 118

Introduction

RAH – 047 C S E

RoofPak

Unit Size RDS 800 = 4000 – 16,000 CFM RDS 802 = 8000 – 20,000 CFM RAH 047 = 12,000 – 30,000 CFM RAH 077 = 23,000 – 50,000 CFM

Heat medium A = Natural gas E = Electric F = Fuel oil S = Steam W = Hot water Y = None

Design vintage

Cooling coil size S = Standard (low airflow) L = Large (high airflow) Y = None or contractor coil

This manual provides general information about the “C” vintage McQuay RoofPak applied rooftop unit, models RDS and RAH. 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.

Introduction

Gas Burner Nameplate

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

Hazard Identification Information

The MicroTech III applied rooftop unit controller is available. For a detailed description of the MicroTech III components, input/output configurations, field wiring and information on using and programming the MicroTech III unit controller, refer to OM 920.

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 Table 1).

Table 1: Program Specific Rooftop Unit Literature

Rooftop unit control configuration

McQuay 208 - 460 V OM 844-1

VFDs

Figure 1: Nomenclature

McQuay 575 V OM 895

Non-McQuay See vendor manuals

Operation manual

number

DANGER

Dangers indicate a hazardous situation which will result in death or serious injury if not avoided.

WARNING

Warnings indicate potentially hazardous situations, which can result in property damage, severe personal injury, or death if not avoided.

CAUTION

Cautions indicate potentially hazardous situations, which can result in personal injury or equipment damage if not avoided.

McQuay IM 987 3

Introduction

Economizer

Filter

Heat

section

Supply fan

discharge

plenum

section

C19, 20

RAT

LT11 (optional)

S11, REC11

SD2

RAE

ACT3

PC5

OAE

VM1

LT10 (optional)

DAT

OAT

SV1, 2

(optional)

section

return air

(optional)

FS1

(optional)

SV5, 6 (optional)

S10, REC10 (optional)

SD1 (optional)

ACT6

Typical Component Locations

Figure 2 shows a typical unit with locations of major

components. These figures are for general information only. See the project’s certified submittals for actual specific dimensions and locations.

Control Locations

All controls are optional. If controls are ordered, Figure 2 shows the locations of the various control components

Figure 2: Control Locations

mounted throughout the units. See Figure 3, page 5 for the locations of control components mounted in control panels. Additional information is included in Table 2, page 12 and the wiring diagram legend, which is included in "Wiring

Diagrams"‚ page 59. Figure 2 shows the blow-through heat

and the blow-through coil sections.

4 McQuay IM 987

Control Panel

Main control panel

Electric heat control panel (optional)

Supply fan section

VFDs, line reactors, and

manual bypass (optional)

Prop exhaust VFDs

(not shown)

(optional)

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.

Figure 3: Control Panel Locations

Introduction

McQuay IM 987 5

Introduction

R24 R25 R28

R20 R26 R27 R28

R30

R45

R60

R69

R58

GCB1

Resistor

keypad

Remote

MCB

EHB1

ERB1

VFD remote

display

REC1

TB1

DHL

SPS1

SPS2

MMP60 MMP10 MMP20

R46

R48

HS1 S1

S7S4

Keypad display

Serial conn

M60

M10

M20

supply

Power

F1A

F1B

F1C

DS1

GND LUG DS1

TB7

blocks

remaining

TB2,

blocks

first seven

TB3,

detail, page 14.

See separate

SPS1,2 fittings

for static

pressure tubing

Figure 4: Typical Main Control Panel, Sizes 800C to 802C, 460 Volt

6 McQuay IM 987

Figure 5: Typical Main Control Panel, Size 047C, 460 Volt

VFD remote

display

GFR1

TB7

SPS1,2

fittings for

static pressure

tubing

TB2

F1A

F1B

F1C

Harness

Plugs

Introduction

McQuay IM 987 7

Introduction

Unit powered outlet and associated disconnect in seperate panel

Figure 6: Typical Main Control Panel, Size 077C, 460 Volt

8 McQuay IM 987

Introduction

M41 M42 M41

M33 M32 M31

FB33 FB32 FB31

FB43 FB42 FB41

PB3

SR2

SR3

SR1

TB11

Figure 7: TypicaL Gas Heat Panel, 1000 MBH

R22

TD10

R20

R23 R21

LS2

Figure 9: VFD Bypass Panel, 40 Hp, 460 Volt

LR10, 20

MMP30, 40

M30, 40

LS1

Figure 10: Electric Heat Panel, Sizes 800C, 802C

FSG

FSG Tim

Figure 8: TypiCal Propeller Exhaust Panel, 3 Fans, 460 Volt

McQuay IM 987 9

Introduction

GLG3

DS3

M41M43

FB41FB42FB43

H53

TB11

M31M32M33

FB31FB32FB33

M42

Figure 11: Electric Heat Panel, Size 047C Figure 12: Electric Heat Panel, Size 077C

FB31FB32FB33

M31M32M33

FB34FB44

M34M44

FB41FB42FB43

M41M42M43

GLG3

DS3

H53

TB11

10 McQuay IM 987

Figure 13: Harness Plug Connector Detail

LT OP1 LT OP2

LT11LT1 0

DFRH DFLH OPEN4

SD1 SD2

GSHT1 GSHT2

HL22 OPEN3

OAE PC7PC5

ACT3 OPEN2

SV12 SV56

AFD10 AFD20

FP1 OPEN1EPTS

RATS OATSDATS

Introduction

McQuay IM 987 11

Introduction

Controls, Settings, and Functions

Table 2 below lists all of the unit control devices and

associated information.

Table 2: Controls, Settings, and Functions

Symbol Description Function Reset Location Setting Range Differential Part no.

DAT

DHL

EFT

FP1, 2

FS1

MCB

OAE

OAT

PC5

PC6

PC7

RAE

RAT

SD1

SD2

SPS1

Discharge air temperature sensor

Duct high limit switch

Entering fan air temperature sensor

Evaporator frost protection

Freezestat

Main control board

Enthalpy control (electromechanical)

Enthalpy control (electronic)

Outside air temperature sensor

Dirty filter switch Senses filter pressure drop

Airflow proving switch

Return air enthalpy sensor

Return air temperature sensor

Smoke detector, supply air

Smoke detector, return air

Static pressure sensor duct #1

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

Processes input information

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

Senses supply fan pressure to prove airflow

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

Senses return air temperature

Initiates unit shutdown if smoke is detected

Converts static pressure signals to voltage signals

N/A

Auto

N/A

Auto

N/A

Auto

N/A N/A N/A 060004705

Auto

N/A

Manual

N/A

Discharge air

section

Main control

panel

Inlet of supply

fan

Return bends of evaporative

coil

Heating

section

Main control

box

Economizer

section

Economizer

section

First filter

section

Final filter

section

Supply fan

section

Economizer

section

Return air

section

Discharge air

section

Return air

section

Main control

box

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

N/A N/A N/A 060006101

“B” or as required

Fully CW

past “D”

(when used

with RAE)

As required

.10" wc (25

Pa)

N/A N/A N/A 049262202

N/A N/A 060004705

N/A N/A N/A 04925001

N/A

0.05–5.0" wc

(12.5–1245.4

Pa)

N/A N/A 072501901

35°F–45°F

(2°C–7°C)

A–D

A–D N/A 049262201

.05-5" wc

(12.5–1245.4

Pa)

.05-5" wc

(12.5–1245.4

Pa)

.03-1.40" wc

(7.5–348 Pa)

0–5" wc (0–1245.4 Pa) 1–6 V (dc) out

.05" wc

(12.5 Pa),

fixed

12°F (7°C),

fixed

Temperature:

3.5°F (2°C) Humidity:

5% fixed

.05" wc

(12.5 Pa)

.05" wc

(12.5 Pa)

.03" wc

(7.5 Pa), fixed

N/A 049545007

065493801

072502001

030706702

065493801

060015801

12 McQuay IM 987

Introduction

Table 2: Controls, Settings, and Functions (continued)

Symbol Description Function Reset Location Setting Range Differential Part no.

SPS2

Static pressure sensor duct #2

Static pressure sensor: building (space) pressure

System switch

ON-OFF-AUTO switch

Converts static pressure signals to voltage signals and sends them to MicroTech III controller

Converts static pressure signals to voltage signals.

Shuts off entire control circuit (except crankcase heaters)

Used to manually switch unit

N/A

Main control

box

Main control

box

Main control

box

Main control

box

N/A

N/A N/A N/A 001355000

N/A N/A N/A

0–5" wc (0–1245.4 Pa) 1–6 V (dc) out

-025–0.25" wc

(-62.3–62.3

Pa)

1–5 V (dc) out

N/A 049545007

N/A 049545006

McQuay IM 987 13

Mechanical Installation

Note: The installation of this equipment shall 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.

CAUTION

Sharp edges on sheet metal and fasteners can cause personal injury. This equipment must be installed, operated, and serviced only by an experienced installation company and fully trained personnel.

Receiving Inspection

When the equipment is received, all items should be carefully checked 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.

Figure 14: Service Clearances, Unit with Housed DWDI Supply Fan

72"

(1829 mm)

All units should be inspected carefully for damage when received. Report all shipping damage to the carrier and file a claim. In most cases, equipment ships F.O.B. factory and claims for freight damage should be filed by the consignee.

Before unloading the unit, check the unit nameplate to make sure the voltage complies with the power supply available.

Unit Clearances

Service Clearance

Allow an approximate service clearance as indicated in

Figure 14. Also, McQuay recommends providing a roof

walkway to the rooftop unit as well as along two sides of the unit that provide access to most controls and serviceable components.

72"

(1829 mm)

Roof

Walkway

Note: Sections with heating and/or cooling coils or DWDI supply fan must have noted service clearance on the control box side.

To Roof

Access

Location

(1524 mm)

B C

60"

Varies With Unit Arrangement

Refer to Certified Drawing & Note

Dimension "X" RDS 800-802 = 90" (2286mm) RAH 47-77 = 96" (2438mm)

24"

(635 mm)

Legend: A = Return Air Section B = Filter Section C = Cooling Section D = Cooling/Supply Fan Section E = Heat Section F = Discharge Plenum Section

14 McQuay IM 987

Figure 15: Service Clearances, Unit with SWSI Plenum Supply Fan

Roof

walkway

To roof

access

location

Varies with unit arrangement. Refer to Certified Drawing and note below.

96"

(2438 mm)

60"

(1524 mm)

72"

(1829 mm)

72"

(1829 mm)

B C

Legend: A = Return air section B = Filter section C = Cooling section D = Cooling/supply fan section E = Heat section F = Discharge plenum section

Dimension "X" RDS 800–802 = 90" (2286mm) RAH 47–77 = 96" (2438mm)

Note: Sections with heating and/or cooling coils or DWDI supply fan must have noted service clearance on the control box side.

E F

Mechanical Installation

Ventilation Clearance

Below 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:

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 Figure 15.

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:

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, install wind screens around the unit, maintaining the clearances specified (see Figure 16). This is particularly important to prevent blowing snow from entering the outside air intake 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 following restrictions must be observed for overhead

obstructions above the air handler section (see

Figure 16):

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 96"

(2438 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.

McQuay IM 987 15

Mechanical Installation

24" (610 mm) Maximum

2" (51 mm)

Minumum

Top of Unit

to Overhead

Obstruction

24" (610 mm) Maximum

Overhead Canopy

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

Flue Box

Figure 16: Overhead Clearance

Figure 17: Side Discharge

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

Side Discharge Opening (Access in Ductwork Must be Removed)

16 McQuay IM 987

Mechanical Installation

Roof Curb Assembly and Installation

Locate the roof curb and unit 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 allows sound and vibration into the occupied space, locate the unit 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.

WARNING

Mold can cause personal injury. Some materials such as gypsum wall board can promote mold growth when damp. Such materials must be protected from moisture that can enter units during maintenance or normal operation.

Install the curb and unit level to allow the condensate drain to flow properly and allow service access doors to open and close without binding.

Integral supply and return air duct flanges are provided with the RAH roof curb, allowing connection of duct work 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 duct work. Assembly of a typical RAH roof curb is shown in Figure 18,

page 18. Parts A through H 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.

Assembly instructions

1 Set curbing parts A through H per dimensions shown

over roof opening or on a level surface (see Figure 18,

page 18). 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 (see Detail A). 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 Weld curbing in place. Caulk all seams watertight.

Remove backing from 0.25" (6 mm) thick × 1.50" (38 mm) wide gasketing and apply to surfaces shown by cross-hatching.

7 Flash curbing into roof as shown in detail view B

(Figure 19).

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.

10 Be sure that electrical connections are coordinated (see

Figure 26).

McQuay IM 987 17

Mechanical Installation

Return

Air

"X"

Inside

87.00"

(2210 mm)

Inside

90.00"

(2286 mm)

94.75"

(2407 mm)

8.75"

(222mm)

See Detail "A"

70.75"

(1797 mm)

"Y"

Inside

81.00"

(2057 mm)

Inside

8.75"

(222 mm)

3.50"

(90 mm)

7.50"

(191 mm)

2.00"

(51 mm)

Supply

Air

3.50"

(90mm)

Equal Length Side Supports

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

Detail A

RAH unit

Dimensions X Y

in mm in mm

047C

38 965 28 711

077C with flat cooling coil and /or 44" SWSI plenum supply fan

157

38 965

077C with staggered or no cooling coil, and/or 49" SWSI plenum supply fan

157

46 1168

Main unit

curb

Unit base

Curb gasketing

2 × 4 nailer strip

Galvanized

curb

Cant strip (not furnished)

Roffing material

(not furnished)

Rigid insulation

(not furnished)Counterflashing

(not furnished)

Flashing (not furnished)

Figure 18: RAH Roof Curb Assembly Instructions

Figure 19: Roofing Detail “B”

18 McQuay IM 987

Figure 20: RDS Roof Curb Assembly Instructions

Return

Air

"X"

Inside

"Y"

Inside

85.00"

(2159 mm)

62.80"

(1594 mm)

"YY"

"XX"

See Detail "A"

38.80"

(984 mm)

20.00"

(508 mm)

Inside

76.00" (1930 mm) Inside

6.80"

(173 mm)

1.50"

(38 mm)

7.50"

(191 mm)

2.00"

(5.1 mm)

Supply

Air

Mechanical Installation

Table 3: Rds Roof Curb Assembly Instructions

Unit size Fan

None 24.0 610 82.0 2083 6.8 173 1.5 38

800–802C

(2) 15” FC 24.0 610 82.0 2083 6.8 173 1.5 38 (2) 15" FC 24.0 610 82.0 2083 6.8 173 1.5 38

30" AF 30.0 762 76.0 1930 6.8 173 4.5 114 30" AF 30.0 762 76.0 1930 6.8 173 4.5 114 40" AF 36.0 914 78.0 1981 14.8 376 3.5 89 40" AF 36.0 914 78.0 1981 14.8 376 3.5 89

X Y XX YY

in mm in mm in mm in mm in mm in mm in mm in mm

Unit size

800–802C

Return

X Y XX YY

fan

None 24.0 610 82.0 2083 6.8 173 1.5 38

McQuay IM 987 19

Mechanical Installation

Seismic hold down brackets

Structural steel frame

Spring isolator

Duct opening

IBC Seismic Compliant Units

It is important to follow these installation instructions for all IBC Seismic compliant McQuay Rooftop units.

IBC Seismic compliant McQuay Rooftop units can be mounted to either a roof curb or a post and rail setup. If using a roof curb, it must be specifically designed for seismic restraint and be IBC seismic compliant (spring isolated or non-isolated type seismic roof curbs are available). Typical construction of a seismic rated roof curb is from structural steel framing and contains seismic hold down brackets for attachment of the rooftop unit (see Figure 21). Post and rail arrangements rated for seismic applications are also available (spring isolated or non-isolated).

IMPORTANT: An acceptable IBC seismic installation provides a direct positive attachment to both the building structure and the roof mounted equipment.

Refer to the roof curb manufacturer’s submittal drawings for actual roof curb assembly, attachment details and rigging instructions for both roof curb and post and rail arrangements.

Roof Curb Arrangement

1 Set the rooftop unit on the roof curb (McQuay Rooftop

units are designed to overhang from the roof curb).

2 Adjust the seismic hold down brackets so they come into

contact with the unit base per Figure 22 and Figure 23,

page 21.

a The seismic hold down brackets should be adjustable

and accommodate the overhang of the rooftop unit.

b If the hold down bracket cannot reach the unit base,

use a shim spacer. See Figure 23, page 21.

3 Weld each seismic hold down bracket (and shim spacer,

if required) to the unit base as shown in the acceptable weld zone detail in Figure 22, page 21.

CAUTION

When welding unit to the curb, do not damage wiring (control panel side). Weld ONLY in the specified zone in the acceptable weld zone (see Figure 22, page 21). Welding must comply with weld fillet size, etc. as indicated in Figure 22, page 21.

Note: High temperature insulation is installed at the factory to

allow for field welding along the lower front edge region of the unit base.

Figure 21: Typical Seismic Roof Curb (Spring Isolated)

20 McQuay IM 987

Figure 22: Welding Of Hold Down Brackets—Unit Base, Cross-Sectional View

Unit base

Seismic hold down bracket

Unit power wiring (by factory)

Unit control wiring (by factory)

High temp Insulation

Roof curb

Acceptable weld zone

Field attachment

weld

Weld zone

.25

.50"

Unit base

Seismic hold

down bracket

Unit power wiring

(by factory)

Unit control wiring (by factory)

Roof curb

Shim

spacer

It may be necessary for the contractor to field fabricate spacers or new seismic hold-downs for rooftop units having larger overhang dimensions.

Figure 23: Shim Spacers On Hold Down Brackets

Mechanical Installation

McQuay IM 987 21

Mechanical Installation

2–48

Rail

.25

Unit power wiring (by factory)

Unit control wiring (by factory)

High temp insulation

Rail

Acceptable weld zone

Field attachment

weld

Weld zone

.50"

Unit base

6–12"

2–48

Rooftop unit

.25

Weld every 48"

6–12"

Rails

Post and Rail Arrangement

1 Set the rooftop unit on the rails. The rails should run

lengthwise and support the entire unit base.

2 Weld both sides of the unit directly to each rail as shown

in Figure 24 and Figure 25.

The total number of welds

required is dependent on the length of the unit.

a Make the fillet welds 2 inches long, spaced 48 inches

apart on centers.

b Place the end welds 6 to 12 inches from the unit edge.

Figure 24: Welding of Unit To Rail—Unit Base, Cross-Sectional View

When welding unit to the curb, do not damage wiring (control panel side). Weld ONLY in the specified zone in the acceptable weld zone (see Figure 24). Welding must comply with weld fillet size, etc. as indicated in Figure 24.

Note: High temperature insulation is installed at the factory to

CAUTION

allow for field welding along the lower front edge region of the unit base.

Figure 25: Weld Locations for Rail Arrangement

22 McQuay IM 987

Mechanical Installation

Unit length minus 6.4

12.1

See Detail A

Detail A

3.4

5.1

0.9 Dia. K.O.

3.0 Dia. K.O.

4.6

4.8

2.0

2.1

4.3

3.1

9.7

8.0

97.0

76.0

6.0

7.5

20.0

1.5

6.0

6.8

OPNG

2Typ

4Typ

OPNG

RPS only

Figure 26: Typical Power Wire Entrance, Curb View (RDS 800C–802C Shown (For Exact Values, Refer to Submittal)

McQuay IM 987 23

Mechanical Installation

99"

5" *

Max.

Note: Maximum recommended width for structural member is 5" (127

mm) to allow for adequate space for duct connections and electrical entry.

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

Rigging cables must be at least as long as distance “A.”

Spreader bars

required

Lift only as indicated

Caution: Lifting points may not

be symmetrical to center of gravity of unit. Balast or unequal cable lengths may be required.

Post and Rail Mounting

When mounting by post and rail, run the structural support the full length of the unit. Locate the structural member at the base of the unit as shown in Figure 27, assuring the I-beam 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. Seal cabinet penetrations (electrical, piping, etc.) properly to protect against moisture and weather.

Figure 27: Post and Rail Mounting

1 Support the unit well along the length of the base rail.

2 Level the unit (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.

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 28 shows an example of the rigging instruction label

shipped with each unit.

WARNING

Use all lifting points. Improper lifting can cause severe personal injury and property damage.

Figure 28: Rigging and Handling Instruction Label

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 is stored at the construction site for an intermediate period, follow these additional precautions:

24 McQuay IM 987

CAUTION

Lifting points may not be symmetrical to the center of gravity of the unit. Ballast or unequal cable lengths may be required.

Mechanical Installation

6 Lifting Points

RDS 800: B Min. = 62" (1515 mm) RDS 802: B Min. = 84" (2134 mm) RAH 47: B Min. = 96" (2438 mm) RAH 77: B Min. = 120" (3048 mm)

Lifting Points

To determine the required lifting cable lengths and whether four-point or six-point lifting is required, use Tables 4 and 5 and Figure 29.

Referring to Figure 29, note that dimension A is the distance between the outer lifting points. The four outer rigging cables must be equal to or longer than dimension A. Dimension B shows the minimum distance between the outer and the inner lifting points for six-point lifting. Use this to roughly determine the required length of the middle cables for sixpoint lifting. Determine dimension A by subtracting dimensions X and Y from dimension Z (e.g., A = Z – X – Y).

• Where:

• Z = Total unit length in inches

(refer to certified drawings for this dimension).

• X = Outdoor/return air section length (refer to Figure 29 and

Table 5 for this dimension).

• If A  288" (7315 mm), 4-point lifting is sufficient.

• If A > 288" (7315 mm), 6-point lifting is required.

Table 4: RAH X Dimension (See Figure 29) Economizer Section

Type of economizer

section

100% OA 0 0

Plenum 48” (1219 mm) 72” (1829 mm)

0–30% OA 48” (1219 mm) 72” (1829 mm)

0–100% economizer 72” (1829 mm) 96” (2438 mm)

0–100% economizer with return fan 72” (1829 mm) 96” (2438 mm)

047C 077C

Figure 29: Unit Type RAH Lifting Points

4 Lifting Points

Table 5: RDS X Dimension (See Figure 29) Outdoor/return Air Section

0–100% economizer with 15" return fan 62" (1575 mm) — 0–100% economizer with 30" return fan 52" (1321 mm) 52" (1321 mm) 0–100% economizer with 40" return fan — 80" (2032 mm)

Outdoor/return air section 800C 802C

100% OA 0 0

Plenum 40” (1016 mm) 52" (1321 mm)

0–30% OA 40” (1016 mm) 52" (1321 mm)

0–100% economizer 40” (1016 mm) 52" (1321 mm)

McQuay IM 987 25

Mechanical Installation

Remove top cap and save for reassembly.

Remove plywood and retaining angles from unit and discard.

Discharge end of unit

Fan end of unit

Remove screws on fan panel, leaving retainer clips in place. Save screws for reassembly.

Split Units

Although units typically ship from the factory as complete units, they can be factory split at the supply fan bulkhead and connected later on the roof. This configuration is ordered if the shipping length or a weight limitation prevents ordering a packaged unit.

A single nameplate is attached to the air handler section and power is supplied to both sections through the optional main control box as in a packaged unit.

RAH Factory Split at Fan

Field reassembly of an RAH unit that shipped split at the fan takes place in three phases: (1) setting the sections,

Figure 30: Set Sections

(2) mechanically recoupling the cabinet, and (3) reconnecting power and control wiring.

Phase I. Set sections

1 Remove top cap and save for Phase II, Step 1.

2 Remove screws on fan panel, leaving retainer clips in

place to secure bulkhead. Save screws for Phase II, Step 5.

3 Remove plywood and retaining angles from unit and

discard.

4 Carefully lower both sections of unit (fan end and

discharge end) into place, making sure the roof curb engages the recesses in the unit base.

26 McQuay IM 987

Phase II. Reassemble cabinet (Figure 31)

Reinstall top cap saved in step 1

Caulk ends of splice cap

See detail

Splice cover, provided

#10 screws, provided

Nut clip-on, provided

Caulk vertical seam

Install screws (.25 to 20 × .75) saved from step 1

1 Reinstall top cap removed in Phase I, Step 1.

2 Caulk (watertight) ends of splice cap.

3 Caulk (watertight) vertical seam.

4 Install #10 screws (provided).

5 Install screws (.25–20 ×.75) removed in Phase I, Step 2.

6 Install splice cover (provided).

Figure 31: Reassemble Cabinet

Mechanical Installation

McQuay IM 987 27

Mechanical Installation

If applicable, install as shown with provided fasteners.

After routing wires, install inner raceway cover (see step 6).

3.72 ref. (94 mm)

Phase III. Reconnect power and control wiring

Once the sections are physically reconnected, the ends of the power harness are fed back through the unit base into the junction box, per the unit’s electrical schematics.

CAUTION

Connect the power block correctly and maintain proper phasing. Improper installation can cause severe equipment damage.

1 Make electrical connections and reinstall inner raceway

cover as shown in Figure 32.

Figure 32: Electrical Connections and Raceway Cover Installation

6 Reinstall the external raceway covers after routing of the

control wires is complete.

Field Refrigerant Piping and Charging of DX Coils

Units that ship from the factory with DX coils installed do not include refrigerant piping or refrigerant controls. The coil assembly is ready for field connections at the distributors and at the suction headers. Piping kits that provide the necessary liquid and hot gas piping and control components are available for field installation. Field-installed refrigerant piping may exit the unit cabinet at one of the following locations:

• Through the floor of the unit.

• Through the discharge and bulkhead of the unit.

• Through a cabinet door near the DX coil that is not required

for service areas.

CAUTION

For any of the above cabinet penetrations, tightly seal the hole to prevent water or air leakage.

In preparing for field piping, remove the plastic plugs on the distributors and unsweat the copper caps at the suction header connections.

3 Run the control harnesses by removing the external

4 Remove the excess harness length from the external

5 Make all electrical connections per the unit’s electrical

When power wire reconnection is complete, reinstall the inner raceway cover in the blank or heat section.

Figure 32 shows a typical installation of the raceway

cover.

raceway covers on either side of the unit split.

raceway on the downstream side of the split; then route 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.

schematics.

Follow piping design, sizing, and installation information presented in ASHRAE handbooks in the design and installation of interconnecting piping. The DX coil and condensing unit are intended to be set at the same elevation, as close as possible to each other to minimize refrigerant pressure drop. Design piping to prevent liquid refrigerant carryover to the compressor and to provide a continuous return of

compressor oil from the system.

CAUTION

The pounds of refrigerant in the system may exceed the capacity of the condenser, depending on the amount of refrigerant in the liquid lines between the DX coil and the condensing unit. Refer to condenser manufacturer for information about refrigerant capacity. Suitable means of containing the refrigerant is required.

CAUTION

To prevent liquid return and damage to the compressor on systems with optional hot gas bypass, it is important to locate the bypass solenoid valve at the condensing unit and not at the DX coil.

28 McQuay IM 987

Mechanical Installation

Piping Recommendations

1 Use type K or L clean copper tubing. Thoroughly clean

or braze all joints with high temperature solder. Base piping sizes on temperature/pressure limitations as recommended in the following paragraphs. Under no circumstances should pipe size be based strictly upon coil or condensing unit piping connection size.

2 Do not exceed suction line piping pressure drop

equivalent to 2°F (1°C), 3 psi (20.7 kPa) per 100 feet (30.5 m) of equivalent pipe length. After the suction line size is determined, check the vertical suction risers to verify that oil will be carried up the riser and back to the compressor. Pitch the suction line(s) in the direction of refrigerant flow and make sure they are adequately supported. Lines should be free draining and fully insulated between the evaporator and the compressor. Install a trap on the vertical riser to the compressor.

3 To determine the minimum tonnage required to carry oil

up suction risers of various sizes, check the vertical suction risers using Table 6. Insulate suction lines inside

the unit cabinet to prevent condensation.

Table 6: Minimum Tonnage (R-22) to Carry Oil Up Suction Riser at 40°F Saturated Suction

Line size O.D. Minimum tonnage

1 1/8" 1.5 1 3/8" 2.5 1 5/8" 3.8 2 1/8" 7.6 2 5/8" 13.10 3 1/8" 20.4 3 5/8" 29.7 4 1/8" 41.3

4 Size the liquid line for a pressure drop not to exceed

the pressure equivalent of 2°F (1°C), 6 psi (41.4 kPa) saturated temperature.

Leak Testing

In the case of loss of the nitrogen holding charge, the unit should be checked for leaks prior to charging the complete system. If the full charge was lost, leak testing can be done by charging the refrigerant into the unit to build the pressure to approximately 10 psig and adding sufficient dry nitrogen to

bring the pressure to a maximum of 125 psig. The unit should then be leak tested with halide or electronic leak detector. After making any necessary repair, the system should be

evacuated as described in the following paragraphs.

WARNING

Do not use oxygen or air to build up pressure. Explosion hazard can cause severe personal injury or death.

Evacuation

After determining the unit is tight and there are no refrigerant leaks, evacuate the system. Use a vacuum pump with a pumping capacity of approximately 3 cu.ft./min. and the ability to reduce the vacuum in the unit to at least 1 mm (1000 microns).

1 Connect a mercury manometer or an electronic or other

type of micron gauge to the unit at a point remote from the vacuum pump. For readings below 1 millimeter, use an electronic or other micron gauge.

2 Use the triple evacuation method, which is particularly

helpful if the vacuum pump is unable to obtain the desired 1 mm of vacuum. The system is first evacuated to approximately 29" (740 mm) of mercury. Then add enough refrigerant vapor to the system to bring the pressure up to 0 pounds (0 microns).

3 Evacuate the system again to 29" (740 mm) of vacuum.

Repeat his procedure three times. This method is most effective by holding system pressure at 0 pounds (0 microns) for a minimum of 1 hour between evacuations. The first pulldown removes about 90% of the noncondensables; the second removes about 90% of that remaining from the first pulldown. After the third pulldown, only 1/10 of 1% of noncondensables remains.

Table 7, page 30 shows the relationship between pressure,

microns, atmospheres, and the boiling point of water.

CAUTION

Before replacing refrigerant sensors or protective devices, see

"Refrigerant Charge"‚ page 31 for an important warning to

prevent an abrupt loss of the entire charge.

McQuay IM 987 29

Mechanical Installation

Table 7: Pressure-Vacuum Equivalents

Absolute pressure above zero Vacuum below 1 atmosphere

Microns PSIA Mercury (mm) Mercury (in)

0 0 760.00 29.921 — —

50 0.001 759.95 29,920 1/15,200 –50

100 0.002 759.90 29.920 1/7,600 –40

150 0.003 759.85 29.920 1/5,100 –33

200 0.004 759.80 29.910 1/3,800 –28

300 0.006 759.70 29.910 1/2,500 –21

500 0.009 759.50 29.900 1/1,520 –12

1,000 0.019 759.00 29.880 1/760 1

2000 0.039 758.00 29.840 1/380 15

4,000 0.078 756.00 29.760 1/189 29

6000 0.117 754.00 29.690 1/127 39

8,000 0.156 752.00 29.600 1/95 46

10,000 0.193 750.00 29.530 1/76 52

15,000 0.290 745.00 29.330 1/50 63

20,000 0.387 740.00 29.130 1/38 72

30,000 0.580 730.00 28.740 1/25 84

50,000 0.967 710.00 27.950 1/15 101

100,000 1.930 660.00 25.980 2/15 125

200,000 3.870 560.00 22.050 1/4 152

500,000 9.670 260.00 10.240 2/3 192

760,000 14.697 0 0 1 atmosphere 212

Approximate fraction

of 1 atmosphere

H2O boiling point at each

pressure (

Charging the System

Units are leak tested at the factory and shipped with a nitrogen holding charge. If the holding charge has been lost due to shipping damage, charge the system with enough refrigerant to raise the unit pressure to 30 psig after first repairing the leaks and evacuating the system.

1 After all refrigerant piping is complete and the system is

evacuated, it can be charged as described in the paragraphs following. Connect the refrigerant drum to the gauge port on the liquid shutoff valve and purge the charging line between the refrigerant cylinder and the valve. Then open the valve to the mid position.

2 If the system is under a vacuum, stand the refrigerant

drum with the connection up, open the drum, and break the vacuum with refrigerant gas.

3 With a system gas pressure higher than the equivalent of

a freezing temperature, invert the charging cylinder and elevate the drum above the condenser. With the drum in this position and the valves open, liquid refrigerant flows into the condenser. Approximately 75% of the total

requirement estimated for the unit can be charged in this manner.

4 After 75% of the required charge enters the condenser,

reconnect the refrigerant drum and charging line to the suction side of the system. Again, purge the connecting line, stand the drum with the connection side up, and place the service valve in the open position.

Important: At this point, interrupt the charging procedure and do prestart checks before attempting to complete the refrigerant charge.

Note: Stamp the total operating charge per circuit on the unit

nameplate for future reference.

CAUTION

Adding refrigerant to the suction always risks liquid-related damage to the compressor.

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.

30 McQuay IM 987

Mechanical Installation

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

( i n . w . o . )

D r a i n P a n

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 "

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

D i m

e n s i o n

V i e w A

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

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 e e V i e w " A "

Refrigerant Charge

Factory-installed DX coils are designed to use R-22. The total charge per circuit is the sum of the following three values:

• Condenser section charge. Refer to manufacturer’s data.

• Evaporator coil charge.

• Charge for length of interconnecting piping installed by

field.

Note: Factory-installed DX coils are intended for one

refrigerant circuit on unit size 800C and two refrigerant circuits containing identical weights of refrigerant on all other sizes. The values shown in Ta bl e 8 and Table 9 are for each circuit.

Note: The total operating charge per circuit should not exceed

the pumpdown capacity per circuit.

Table 8: Approximate DX Coil Refrigerant Charge Per Circuit

Unit size

047C 3 x no. of DX rows 3.5 x no. of DX rows 077C 5 x no. of DX rows 6.5 x no. of DX rows

Table 9: Approximate Refrigerant Charge Per Circuit

Unit size Evaporator coil (lbs/ckt/coil row)

802 3.30

802C* 2.45

Note: * The RDS 802C unit has two refrigerant circuits.

DX Coil R-22 charge (lbs./circuit)

Flat coil Staggered coil

• 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.

• On units with staggered cooling coils, the upper drain pan drains into the lower coil drain pan through a copper tube near the center of the drain pan. Check that this tube is open before putting the unit into operation and as a part of routine maintenance.

• Because drain pans in any air conditioning unit have some moisture in them, algae, etc. will grow. Periodically clean to prevent this buildup from plugging the drain and causing the drain pan to overflow. Clean drain pans to prevent the spread of disease. Cleaning should be performed by qualified

personnel

WARNING

Drain pans must be cleaned periodically. Material in uncleaned drain pans can cause disease. Cleaning should be performed by qualified personnel.

Figure 33: Condensate Drain Connection

Unit Piping

Condensate Drain Connection

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

• Units may have positive or negative pressure sections. Use traps in both cases with extra care given to negative pressure sections. In Figure 57, dimension “A” should be a minimum of 8" (203 mm). As a conservative measure to prevent the cabinet static pressure from blowing or drawing the water out of the trap and causing air leakage, dimension A should be two times the maximum static pressure encountered in the coil section in inches wc.

• Draining condensate directly onto the roof may be acceptable; refer to local codes. Provide a small drip pad of stone, mortar, wood, or metal to protect the roof against possible damage.

• If condensate is piped into the building drainage system, pitch the drain line away from the unit 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.

Gas Piping

See the “Installation” section of the gas-fired furnace installation manual, Bulletin No. IM 684 or 685.

McQuay IM 987 31

Mechanical Installation

Supply

Bypass

2.12 " ODM Copper Coil Connections

Upper Coil

Air Flow

Lower Coil

Piping for Steam, Hot Water/ChIlled Water Coils

Factory-installed chilled water coils are installed in a coil section that can be designed to accept a factory-installed heating coil immediately upstream. The coil section can be ordered in either the draw-through or blow-through position. All chilled water piping can be done internal to the unit without requiring a piping vestibule (except on sizes 800–802 when heating coils are included in the cooling coil section).

Steam and hot water coils can be factory installed in either a heat section, or in the combination coil section. These sections can be located either in the draw-through or blow-through position. When a steam or hot water coil is installed in the heat section, all piping can be done internal to the unit without requiring a piping vestibule. Refer to Figure 35, page 33 and

Figure 37, page 34

When a steam or hot water coil is installed in the combination coil section, the coil connections project to the inside surface of the door panel. Holes can be cut in the door panels to connect the piping to the coils, or an accessory piping vestibule can be added to the unit to provide piping space. Refer to the section on vestibule assembly instructions. The piping can then be routed back within the unit as shown in

Figure 35, page 33.

When no factory piping or valve is included, the coil connections are 1.625” ODM copper on 800 and 802C, and

2.125" ODM copper on 047 and 077C.

With the factory piping and valve package, the two coils are piped in parallel and controlled through a single three-way valve. Field piping connections are of the same NPT size as the valve-male threads at the supply connection, female threads at the return connection.

Figure 34: Hot Water Heat Section (Shown with Factory Valve and Piping)

To avoid piping penetrations through the roof external to the curb, holes can be cut through the floor of the unit at the

locations specified on the certified drawings.

CAUTION

Seal all holes in the unit floor to prevent water leakage into the building.

Hot Water Piping

Hot water coils are provided without valves for field piping or piped with three-way valves and actuator motors.With the factory piping and valve package, the two coils are piped in parallel and controlled through a single three-way valve. Field piping connections are of the same NPT size as the valve-male threads at the supply connection, female threads at the return connection.

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. Refer to the “Maintenance” section of this manual for more on winterizing coils. The hot water section consists of two stacked soils, as shown in Figure 34.

The valve actuator spring returns to a stem up position upon power failure. This allows full flow through the coil.

Refer to the certified drawings for the recommended piping entrance locations. Seal all piping penetrations to prevent air and water leakage.

Note: Factory-installed water valves and piping are bronze,

brass, and copper. Dissimilar metals within the plumbing system can cause galvanic corrosion. To avoid corrosion, provide proper di-electric fittings as well as appropriate water treatment.

CAUTION

Coil freeze possible. Can damage equipment. Follow instructions for mixing antifreeze solution used. Some products have higher freezing points in their natural state than when mixed with water. The freezing of coils is not the responsibility of McQuay International. Refer to "Winterizing

Water Coils"‚ page 111.

32 McQuay IM 987

Mechanical Installation

Return

Lower Coil

2.12 " ODM Copper Coil Connections

Upper Coil

Supply

Return

Steam Coil Piping (All Units)

The steam heat section consists of two stacked coils pitched at 1/8" (3 mm) per foot (305 mm) as shown in Figure 35 to provide positive condensate removal. When no factory piping or valve is included, the coil connections are 2.5" male NPT iron pipe.

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

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

Figure 35: Steam Heat Section (Shown with Factory Valve and Piping)

With the factory piping and valve package, the two coil supplies are piped in parallel and controlled through a single two-way valve. The field supply connection is of the same female NPT size as the valve. Field return connections are made at the 2.50" male NPT fittings on each of the two stacked coils.

Note: Refer to the sections on steam coil piping and trap

recommendations for additional information.The valve actuator spring returns to a stem up position upon power failure. This allows full flow through the coil.

Figure 36: Two-Way Valve Package

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, the vacuum breaker is to be connected between the coil inlet and the return main. However, if the system has a flooded return main, the vacuum breaker to the atmosphere; the trap design should allow venting of the 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 when using modulating

or on-off control.

6 Pitch all supply and return steam piping down a

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

McQuay IM 987 33

Mechanical Installation

S t e m

S e t s c r e w s

S t e m C l i p

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 on-off control only.

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

connection.

4 Always install strainers as close 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.

Figure 37: Heating Coil Piping with Vestibule

Steam Coil Freeze Conditions

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

1 Supply 5 psi (34.5 kPa) steam to coils at all times.

2 Modulating valves are not recommended. Control should

be by means of face and bypass dampers.

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

sufficiently far below the coil to provide an adequate hydrostatic head to ensure 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.

4 If the unit is to be operated in environments with

possible freezing temperatures, an optional freezestat is recommended. See “Freeze Protection” on page 95 for additional information.

Figure 38: Valve Assembly

Figure 39: Steam Valve Package

34 McQuay IM 987

Mechanical Installation

Air Flow

Bypass

Supply

Return

Chilled Water Piping

Chilled water coils are provided without valves for field piping, or piped with three-way valves with motor actuators.

Table 10 provides information on units with factory installed

piping and valve packages. The table also provides field sweat connection information for units not furnished with factory installed piping and valve packages.

With the factory piping and valve package, the coil assembly is controlled through a single three-way valve. When two coils are included in the assembly, they are piped in parallel. Field connections are male NPT, sized as shown in Table 10. Refer to Figure 40 for a typical cooling coil with factory valve and piping.

Figure 40: Chilled Water Coil (with Factory Valve and Piping)

McQuay IM 987 35

Mechanical Installation

Table 10: Piping Connection Sizes/Valve Size Options for Chilled Water Piping

Cabinet

size

047C

077C

Application

code

Blow-thru or

draw-thru small

coil section

Blow-thru or

draw-thru large

coil section

Face and bypass

section with

small coil

Face and bypass section with large

coil

Blow-thru or

draw-thru small

coil section

Blow-thru or

draw-thru large

coil section

Face and bypass

section with

small coil

Face and bypass section with large

coil

Coil size

Hx 83"

(2108 mm)

long

33 + 33

(2 coils) (838

838 mm)

39 + 39

(2 coils) (991

991 mm)

(1219 mm)

39 + 39

(2 coils) (991

991 mm)

45 + 45

(2 coils)

(1143 +

1143 mm)

63 + 63 (2 coils) (1600 +

1600 mm)

(1600 mm)

54 + 54 (2 coils) (1372 +

1372 mm)

Face area sq.

ft. (sq. m)

38.0

(3.53 m²)

45.0

(4.18 m²)

27.7

(2.57 m²)

45.0

(4.18 m²)

51.9

(4.82 m²)

72.6

(6.74 m²)

36.3

(3.37 m²)

62.3

(5.74 m²)

Available rows

(available with 8,

10, 12 fins/in)

3DRDQ——AQAP 4 DRDQBQBQBP 5DRDQ——BQAP 6 DRDQBQBQAP 8 DRDQBQBQBP 3DRCQ——AQAP 4DRCQCQCQBP 5DRCQ——CQAP 6DRCQCQCQAP 8DRCQCQCQBP 3 FUET——ASAS 4 FUETCSCSCS 5FUET——CSAS 6FUETCSCSAS 8 FUETCSCSCS 3DRCQ——AQAP 4DRCQCQCQBP 5DRCQ——CQAP 6DRCQCQCQAP 8DRCQCQCQBP 3 CRCQ——APAP 4 CRCQCPBPBP 5 CRCQ——BPAP 6 CRCQCPBPAP 8 CRCQCPBPBP 3 BQBP——APAP 4 BQBPBPBPBP 5 BQBP——BPAP 6 BQBPBPBPAP 8 BQBPBPBPBP 3 ETCS——ASAS 4 ETCSCSCSCS 5ETCS——CSAS 6 ETCSCSCSAS 8 ETCSCSCSCS 3 CRCQ——APAP 4 CRCQBPBPBP 5 CRCQ——BPAP 6 CRCQBPBPAP 8 CRCQBPBPBP

5WH 5WL 5WS 5WM 5WD

Columns (see next page for explanation)

1 2 1 2 1 2 1 2 1 2

Available circuiting

36 McQuay IM 987

Mechanical Installation

Table 10: Piping Connection Sizes/Valve Size Options for Chilled Water Piping

3 G T G T —————— 4 GTGTGT———— 5 G T G T —————— 6 GTGTGT———— 3 G T G T —————— 4 GTGTGT———— 5 G T G T —————— 6 GTGTGT———— 3 — L —M ——— N — N 4 — L —M—M—N—N 5 — L —M ——— N — N 6 — L —M—M—N—N 8 — L —M—M—N—N

10 — L —M——— N — N

3—L—M—K—N—N 4 — L —M ——— N — N 5—L—M—K—N—N 6—L—M—K—N—N 8—L—M—K—N—N

10 — L — M — K — N — N

800

802

Blow-thru or

draw-thru cooling

only coil section

Blow-thru or

draw-thru unit

coil section

Face and bypass

section with

small coil

Blow-thru or

draw-thru

contractor coil

section

48 + 78 (1220 +

1981 mm)

48 + 78 (1220 +

1981 mm)

30 + 79

(763 +

2006 mm)

36 + 79

(915 +

2006 mm)

26.0

(2.42 m²)

26.0

(2.42 m²)

16.5

(2.57 m²)

19.8

(4.18 m²)

Table 10 Available Circuiting Legend

Column 1:

These units are available with a factory installed package consisting of a three-way water valve and connecting piping.

A = This combination is not available with a factory-installed piping and valve package. B = 300, 2.50, or 200 inch three-way valves can be specified C = 300, 2.50, 2.00, or 150 inch three-way valves can be specified D = 250, 200, or 150 inch three-way valves can be specified E = 250, 200, 150, or 1.25 inch three-way valves can be specified F = 200, 1.50, or 125 inch three-way vales can be specified G = 1.25, 1.50, 2.00 or 2.50 inch three-way valves can be specified Field supply and return female NPT connection sizes are the same as the valve size.

Column 2:

The following letters designate units that are not furnished with the factory installed piping/valve package. Required are field sweat connections, at one or two coils, to male copper tubing for the supply and return water piping.

K = A single 2.00 inch NPT supply and return if fin height is 21–30 inches and 2.50 inches of fin height is 30–36 inches. L = A single 1.50 inch NPT supply and return M = A single 2.00 inch NPT supply and return if fin height is 21–30 inches N = A single 2.50 inch NPT supply and return P = Two 3.12 inch O.D. supply and two 3.12 O.D. return connections Q = Two 2.62 inch O.D supply and two 2.62 O.D. return connections R = Two 2.12 inch O.D. supply and two 2.12 O.D. return connections S = One 3.12 inch O.D supply and one 3.12 O.D. return connections T = One 2.62 inch O.D supply and one 2.62 O.D. return connections U = One 2.12 inch O.D supply and one 2.12 O.D. return connections

McQuay IM 987 37

Mechanical Installation

Door Latch Assembly

Door

Vestibule Assembly Instructions

An accessory vestibule is available to provide additional piping space for coils installed in a four-foot section. A vestibule is required to maintain door access on a combination heating and cooling section. Assemble the vestibule to the unit part by part as shown in Figure 41.

Note: The door, hinge, and latch assemblies from the unit are

used on the vestibule.

Step 1

Remove door from section where vestibule is to be located by removing screws holding hinges to upright support (leave hinges on door). Set door aside and save for Step 4.

• Remove door latch assembly from other side upright support. Use offset Phillips screwdriver or a wrench to remove screws holding latch assembly in place. Save door latch assembly, screws and bushings for Step 4.

Figure 41: Step 1 Illustration

Step 2

Remove gasketing around door flange and save for use on vestibule. See Step 4. Remove door and save for Step 4.

Figure 42: Step 2 Illustration

Gasketing

Door Prop

38 McQuay IM 987

Mechanical Installation

Upright Angle

#10 Screw

Gasketing

Silicone Sealant

Door Latch Assembly (See Note)

Door Prop

Door

Silicone Sealant

Gasketing

Upright Angle

Step 3

1 Assemble side panels A and B to uprights using #10 drill

screws supplied. Make certain side panels are flush against uprights before securing into place.

2 Fasten bottom panel D to base channel using #10 drill

screws and to side panels A and B using #10 screws supplied.

3 Set top panel C in place and fasten to side panels A and

B using #10 screws and to top panel using #10 screws supplied.

Figure 43: Step 3 Illustration

#10 Screw

#10 Drill Screw

Step 4

Reassemble access door to vestibule by screwing hinges

into side panel using screws saved from Step 1. (Access door must be attached to the vestibule in the same opening direction as it was on the unit.)

2 Remove and discard latch handle locking screws and

retaining washer. Fasten door latch assembly to side panel using screws and bushings saved from Step 1. (Latch must be fastened on the same side as when located on the unit.)

3 Fasten upright angles to vestibule using #10 screws

supplied.

4 Seal between unit and vestibule with silicone sealant

along top and sides as shown.

Note: Any holes cut in the floor of the unit must be sealed to

prevent water leakage.

Figure 44: Step 4 Illustration

#10 Screw

McQuay IM 987 39

Mechanical Installation

Closed

Open

90°

Stroke

.25" (6mm)

Outside

Air

Outside

Air

Optional Return Air Fan

Economizer

.500 (13mm) Dia. Shaft

x 1.30" (33mm) Long

Closed

Open

3.00

.25

.75

90°

Stroke

Shaft .500 Dia.

x 1.50 Long

RAH 047C - 077C

RDS 800C & 802C

Damper Assemblies

The optional damper assemblies described in this section normally are ordered with factory-installed actuators and linkages. The following sections describe operation and linkage adjustment of the factory option.

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

Figure 45: Economizer Dampers

linkage also can be used for connecting a damper operator. The damper is set so that the crankarm moves through a 90-degree angle to bring the economizer dampers from full open to full close (see Figure 45). Access to the actuator and linkage is from the filler section. Mechanical stops are placed in the crankarm mounting bracket. Do not remove stops. Driving the crankarm past the stops results in damage to the linkage or damper. The unit ships with a shipping bolt securing the linkage crankarm. Remove shipping bolt before use.

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 “over close” 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.

40 McQuay IM 987

Mechanical Installation

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

closed

open

90

stroke

.25" (6mm)

Airflow

Intake Hood Damper (0% to 100% outside air, RAH 047C–077C only)

Units requiring 100% outside air are provided with a rain hood and dampers that can 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 III 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 46: Intake Hood Damper, 0% To 30% Outside Air

Figure 47: Intake Hood Damper Adj., 0% to 100% Outside Air

Note: Figure 46 shows the RAH 47–77 (The linkage is on the

RH side). The RDS 800–802 are the same except the linkage is on the LH side.

McQuay IM 987 41

Mechanical Installation

CLOSED

OPEN

90°

STROKE

.25" (6 mm)

.75"

(19 mm)

3.00"

(76 mm)

CLOSED

OPEN

Mixing Box (RAH 047C–077C only)

This section uses an outside air damper and a return air damper. Using these dampers allows outside air to blend with return air. Synchronized operation of the dampers is accomplished by interconnecting rods. As one damper section opens, the other section is closed. A total of 100% cfm is always drawn from this section. Damper positioning can be manually or automatically adjusted. With a field-installed controller, automatic operation can be obtained.

Figure 48: Mixing Box

These dampers provide a similar function to economizer dampers. This option differs from an economizer in that no unit mounted exhaust dampers are provided.

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 “over close” low leak damper blades. The edge seal should just lightly contact the adjoining blade. The blades lock up if they are closed so far that the seal goes over center.

42 McQuay IM 987

Face and Bypass Dampers

Airflow

.75"

(19mm)

90°

Stroke

Face Dampers Open

Face Dampers Closed

3.00"

(76mm)

Face and Bypass Damper

.75"

(19mm)

Open

Closed

.25"

(6mm)

90°

Stroke

3.00"

(76mm)

Airflow

Bypass Damper

Face Damper

Face and bypass dampers are available in a flat arrangement for use with heating coils and standard face area cooling coils, as well as a staggered arrangement for large face area cooling coils. The damper sets are linked through a jack shaft for connection to a single actuator (factory or field installed).

Figure 49: Face and Bypass Dampers, RDS 800C–802C Only

Mechanical Installation

Figure 50: Face and Bypass Dampers, Staggered Arrangement—RAH 047C–077C Only

McQuay IM 987 43

Mechanical Installation

Figure 51: Face and Bypass Dampers, Flat Arrangement—RAH 047C–077C Only

Optional

Contractor

Coil

Face and Bypass Dampers

Face and Bypass Damper

Extended Shaft

Cabinet Weather Protection

This unit ships from the factory with fully gasketed access doors and cabinet caulking to provide weather resistant operation. After the unit is set in place, inspect all door gaskets for shipping damage and replace if necessary.

Protect the unit from overhead runoff from overhangs or other such structures.

Recaulk field-assembled options such as external piping or vestibules per the installation instructions provided with the option.

CAUTION

Transportation, rigging, or maintenance can damage the unit’s weather seal. Periodically inspect the unit for leakage. Standing moisture can promote microbial growth, disease, or damage to the equipment and building.

44 McQuay IM 987

Mechanical Installation

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

U n i t B a s e

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

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

Installing Ductwork

On bottom-supply/bottom-return units, if a McQuay roof curb is not used, 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. Do not support the total weight of the duct work from the unit or these duct flanges. See Figure 52.

Units with optional back return, side discharge, or end discharge all have duct collars provided. To expose the discharge duct collars on a side discharge unit, remove 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.

To minimize losses and sound transmission, design duct work per ASHRAE and SMACNA recommendations.

Figure 52: Installing Duct Work

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

WARNING

Mold can cause personal injury. Materials such as gypsum wall board can promote mold growth when damp. Such materials must be protected from moisture that can enter units during maintenance or normal operation.

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. Once duct work is installed in units with side discharge, access to plenum-mounted components is difficult.

McQuay IM 987 45

Mechanical Installation

St atic pressure

tubing

Installing Duct Static Pressure Sensor Taps

For all VAV units, field install and connect duct static pressure taps to the pressure sensors in the unit. Sensor SPS1 is standard; additional sensor SPS2 is optional. These sensors are located in the main control panel (see "Control Panel"‚ page

5).

Carefully locate and install the duct static pressure sensing tap. Improperly locating or installing the sensing tap causes unsatisfactory operation of the entire variable air volume system. Below are pressure tap location and installation recommendations. The installation must comply with local code requirements

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

each tube near the sensor fitting. This facilitates 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. McQuay recommends 1/4" plastic tubing.

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 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 a bare tube end is used, it must be smooth, square (not cut at an angle) and perpendicular to the airstream (see Figure 54).

7 Locate the reference pressure (LO) tap somewhere near

the duct pressure tap within the building (see Figure 53). 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 53). Connect the tubes to appropriate barbed fittings in the control panel. (Fittings are sized to accept 1/4" plastic tubing.)

Figure 53: Static Pressure Tubing Entrance Location

Figure 54: Pressure Sensing Tubing Installation

Main Cont rol Panel

"HI line"

"LO" line

To Sensor "HI" input

Remote Sense Point

Ductwork

(Remote Location)

Rubber Grommet

SPS1

Tubing Extends thru Approx. 1/8"

Roof

46 McQuay IM 987

To Sensor "LO" Input

Pressure Sensing Tubing

Mechanical Installation

Installing Building Static Pressure Sensor Taps

If a unit has direct building static pressure control capability, you must field install and connect static pressure taps to pressure sensor SPS2 in the unit. This sensor is located at the bottom of the main control panel next to terminal block TB2.

Carefully locate and install the two static pressure sensing taps. Improper location or installation of the sensor taps causes unsatisfactory operation. Below 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. If you must remove tubing from a pressure sensor fitting, use care. Do not use excessive force or wrench the tubing back and forth to remove; the fitting can break off and damage sensor.

Building Pressurization Applications

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

each tube near the sensor fitting. This facilitates 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 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 (see Figure 53,

page 46). Connect the tube to the 1/4-inch HI fitting for

sensor SPS2.

5 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 it is not affected by snow. Not

connecting the reference tap to the sensor results in unsatisfactory operation.

6 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.

7 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 (see Figure 53, page 46). Cut this “mouse hole” in the vertical portion of the edge. Seal the penetration to prevent water from entering. Connect tube to the 1/4-inch LO fitting for sensor SPS2.

Lab Pressurization Applications

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

each tube near the sensor fitting. This facilitates 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 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" wc).

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

surrounding the controlled space. Not locating the reference tap to the sensor results in unsatisfactory operation.

5 Locate both taps so 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 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 (see Figure 53,

page 46).

7 Connect the tube to the 1/4-inch HI fitting for sensor

SPS2.

McQuay IM 987 47

Electrical Installation

Hinge and Latch Cap

Access Panels

To p

Bottom

Must Seal

Access Panel

Bottom

Base Frame

Electric heat control panel

Optional

disconnect

(DS3)

3" power

knockouts

Optional

disconnect (DS2)

3" power

knockouts

Main disconnect (DS1)

or power block (PB1)

Electrical Installation

Field Power Wiring

All of the unit side panels are hinged. Do not mount disconnect switches and/or motor starters on panels that provide access to internal components. Wiring conduits can penetrate the cabinet bottom, base frame, or through the hinge and latch cap without interfering with the access panels.

Note: Seal all holes cut into the unit to prevent water leakage.

Seal conduits connecting the unit to external panels, which will be exposed to relative humidity and air pressure differentials. Ground the motor using copper or other corrosion resistant conductor.

Figure 55: Field Power Wiring

overload. Before replacing a fuse, circuit breaker, MMP, or restarting a fan motor, identify the trouble and correct.

According to the National Electrical Code, a disconnecting means shall be located within sight of and readily accessible from the air conditioning equipment. The unit can 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 rated overcurrent protection device (MROPD) appears on the unit nameplate.

All RDS and RAH Units

All units are provided with internal power wiring for single or dual point power connection. The power block or an optional disconnect switch is located within the main control panel. 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. See Figure 56 and Table 12, page 50.

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.

Wiring must comply with all applicable codes and ordinances. The warranty is voided if wiring is not in accordance with these specifications. An open fuse, tripped circuit breaker, or Manual Motor Protector (MMP) indicates a short, ground, or

If the unit has a factory mounted disconnect switch, generally the switch must be turned off to open the main control panel door. However, the door can be opened without disconnecting power by following the procedure covered on page 126. If this is done, use caution since power is not removed from the unit or the controller.

Note: To wire entry points, refer to certified drawings for

dimensions.

Figure 56: RDS and RAH Power Wiring Connections

48 McQuay IM 987

Electrical Installation

R e m o v e L i f t i n g B r a c k e t ( I f L o c a t e d H e r e ) B e f o r e D r i l l i n g H o l e

M a i n C o n t r o l P a n e l

2 . 7 5 " ( 7 0 m m )

3 " ( 7 6 m m )

M a x

D i a .

1 6 "

( 4 0 6 m m )

Figure 57: Optional Side Power Wiring Entrance

• The preferred entrance for power cables is through the bottom knockouts provided on the unit. If side entrance is

the only option, a drilling location is provided.

CAUTION

Wires are located in base rail. Move wires before drilling hole through base rail.

Follow the drilling dimensions exactly to prevent damage to the control panel. The dimensions provided are the only possible point of side entrance for the power cables.

Figure 58: Typical Power Wire Entrance, Unit View—RDS 800C Shown (Actual Opening Shown on Submittal Documents)

20.0

10.0

6.0

76.0

3.8

86.5

94.0

3.8

Supply air opening

10.0

1.50 MPT drain

Detail B

3.8

0.9 Dia. K.O. (Qty 4)

Bottom ret urn opening

24.3

Va r ie s

based on

options

17.7

22.3

12.9

15.3

3.0 Dia. K.O. (Qty 3)

6.8

11. 9

12.0

Reference from leaving air end of section

8.8

7.6

6.6

3.8

McQuay IM 987 49

Electrical Installation

All Units

The minimum circuit ampacity (wire sizing amps) is shown on the unit nameplate. Refer to Table 23 on page 59 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. Size wires 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 constitutes product abuse. It can cause severe damage to the unit's electrical components.

A ground lug is provided in the control panel for each disconnect or power block. Size grounding conductor in accordance with Table 250-122 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 in through a 7/8" knockout in the bottom of the main control panel, near the power wire entry point.

Table 11: Multiple Point Power Connection Options

Number of

electrical

circuits

Disconnect

designation

DS2

DS1 Balance of unit Main control panel

DS3 Electric heat

DS1 Balance of unit Main control panel

Load

Supply and return fan

motors plus controls

Location

(see Figure 2,

page 4)

Main control panel

Electric heat

control panel

Table 12: Recommended 3-phase Power Wiring To Ensure Disconnects and Power Blocks Mate with Power Wiring

Wire

gauge

10 1 75 1 1/2 35

8 1 75 1 3/4 50 6 1 75 1 1 65 41 75 1 1 1/4 85 3 1 75 1 1 1/4 100 2 1 75 1 1 1/4 115

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

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

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

250 2 75 2 2 1/2 510 300 2 75 2 2 1/2 570 350 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

Note: All wire sizes assume separate conduit for each set of parallel

conductors.

Note: All wire sizes based on NEC Table 310-16 for 75°C THW wire

(copper). Canadian electrical code wire ampacities may vary.

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

Qty./

pole

Insulation

rating

(°C)

No. of

conduits

Conduit

(trade size, in.)

For MCA

up to

(amps)

50 McQuay IM 987

Electrical Installation

Main control panel

24V field terminal

block (TB2)

Control wiring raceway cover (remove for access to harness from main control box to unit-mounted control devices)

Field Control Wiring

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 IM 919, “MicroTech III® Unit Controller for Applied Rooftop and Self-Contained Systems.” Refer to the unit wiring diagrams for additional installation information.

Wiring must comply with applicable codes and ordinances. The warranty is voided if wiring is not in accordance with these specifications.

All field control wiring connections are made at the class II terminal block TB2, which is located in the main control panel. Field wiring connections to the 115-volt receptacle and lights are made at terminal block TB7, which is also located in the main control panel. Refer to Figure 59 and "Control Panel"‚

page 5. Two 7/8" knockouts are provided for wire entry.

Figure 59: Field Control Wiring Connections

Interconnecting wiring enters the air handler unit through 7/8" knockouts in the bottom of the main control panel. The interconnecting wiring is connected to TB4 in the air handler unit. Refer to Figure 60. A 7/8" knockout is also available in the end of the unit base as shown in Figure 59.

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

above the roof line between the air handler and condensing units, install the 24V wiring as a NEC Class I wiring system.

Figure 60: Interconnecting Control Wiring

Main

ontrol

panel

TB4

DS2

PB1/DS1

To condensi unit

WARNING

Electrical shock hazard. Can cause severe injury or death. Connect only low voltage NEC Class II circuits to terminal block TB2. Reinstall and secure all protective deadfront panels when the wiring installation is complete.

McQuay IM 987 51

Mechanical Installation

Hold-down fasteners

This bracket is added,

and these 3/8" tie downs

are used for RDS 800C.

This bracket is added,

and these 3/8" tie downs

are used for RDS 800C.

3 /8 " ± 1 /4 " with fan running

Leveling screw

Spring mount

assembly

Cross

channel

Jam nut

Fan base

Mechanical Installation

Preparing Unit for Operation

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 61: RAH Spring Mount Hold Down Fasteners

Spring Isolated Fans

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 64 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 63: Fan Spring Mount Adjustment

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

dimension. Recheck after thrust restraints are adjusted.

Adjusting Spring Mounts

To change spring compression:

Loosen the 5/8-18 UNF hex nut.

Place some additional weight on the fan sled frame (use a lever to slightly compress the spring/or raise the sled) to allow the bolt to turn freely.

Place one or two drops of oil on the threads if needed. Use a wide, flat-blade, socket drive bit with a recommended 1/2” drive handle. Ensure that as the slotted bolt is turned, the upper-rebound plate also turns. This action allows the bolt to compress/decompress the compression plate, while having the same affect on the spring. If the spring is compressed too much, lift the sled before turning. If the spring is not compressed enough, place weight on the sled corner to force it down before turning.

Re-adjust the position of the lower-rebound plate so that the sled has at least 3/4” travel and no more than 1-1/4” travel.

Figure 64: Spring Mount

Figure 62: Spring Mounted Hold-down Fasteners, All Units

52 McQuay IM 987

WARNING

Adjustment assembly

Scroll damper

Thrust restraint adjustment (with fan off)

Note: 1. Loosen jam nuts A. Note: 2. Turn nut C until spring cup and washer contact thrust

restraint angle. Note: 3. Turn nut B until spring is compressed by two turns of nut B. Note: 4. Tighten jam nuts A.

Moving machinery hazard. Can cause severe injury or death. Start the fans for the first time according to the “Check, Test, and Start Procedures” on page 106. If this is not done, equipment damage, severe personal injury, or death can occur.

Relief Damper Tie-Down

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

Adjusting Scroll Dampers

Mechanical Installation

fan housing frame. Refer to Figure 66. When the fan is turned on, the fan moves back to a level position and the thrust restraint spring compresses.

Figure 66: Thrust Restraint Adjustment

Jam nut A

Nut B

Spring clip

Washer

Nut C

Jam nut A

Fan bulkhead

Two sets of scroll dampers are provided in the housing of the twin 15" x 6" supply fan to allow control of air volume to each fan wheel. At the factory, these dampers are fully closed, unrestricting airflow. If fan paralleling occurs, correct it by loosening the adjustment screw on top of the fan housing (see

Figure 65) and slightly lowering the rod until air distribution

between the fans is even.

Figure 65: Scroll Damper Adjustment

Thrust restraint angle

Fan housing frame

Detail A

See Detail A

Adjusting Supply Fan Thrust Restraints

Thrust restraints are provided when housed double-width fans are mounted on springs. After the spring mounts are adjusted for level operation when the fan is running, check the thrust restraints. With the fan off, set the adjustment nuts so the spring is slightly compressed against the angle bolted to the

McQuay IM 987 53

Mechanical Installation

Adjusting Seismic Restraints

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

The position the fan assumes during normal operation is determined by actual job site airflow and static pressure. Therefore, for proper operation, field adjust the seismic restraints 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 limits movement of the spring mounted fan assembly to 0.25" (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 is centered within the 2" (51 mm) diameter hole in the restrainer angle, and the restrainer angle is centered vertically between the flanges of the neoprene center bumper. This results in 0.25" (6 mm) clearance in all directions. When the fan is turned off, the restrainer angle may come to rest on the neoprene center bumper.

Figure 67: Cross Section of Seismic Restraint

Fan base channel

Snubber restrainer angle

Adjust up or down or back and forth

Snubber neoprene

bumper

.25 (6 mm) gap

(fan running)

Snubber neoprene

bumper

Adjust in and out

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 in and out adjustment.

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

54 McQuay IM 987

Sequences of Operation

The following sequences of operation are for a typical “C” vintage applied rooftop unit equipped with MicroTech III, an economizer, 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 59 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 III 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

When primary power is connected to the unit, 115 V (ac) power is fed through control circuit transformer T1 and control circuit fuse F1C (line 166, Figure 75, page 67).

When system switch S1 (line 203, Figure 78, page 70) is closed, low voltage transformers T2 (line 203, Figure 78,

page 70), and T9 (line 802, not shown) energize, and 115 V

(ac) power is supplied to the following:

• The supply fan VFD (line 135-137, Figure 74, page 66)

• M40A to energize the return fan VFD (line 147-149,

Figure 75, page 67)

• Heating control panel (line 603, Figure 88, page 80)

• Economizer actuator (lines 256-257, Figure 79, page 71)

Transformer T2 supplies 24 V (ac) power to the following terminals:

• 24V and COM on the main control board MCB (lines 207 and 208)

• Switch S7 On-Auto-Off (line 216)

• Enthalpy sensor OAE (line 247)

• External time clock contacts (line 215)

• Airflow interlock switch PC7 (line 228)

• Dirty filter switches PC5 and PC6 (lines 242 and 247, not

shown)

• Gas furnace alarm relay R24 (line 225, not shown)

• Freezestat switch FS1 (line 243, hot water or steam heat

only)

• Smoke detectors SD1 and SD2 (line 220)

The time clock, S7 switch, and emergency shutdown terminals (lines 214-222) control fan operation.

Note: Unit ships with factory installed jumpers between TB2

101 and 105 and between 101 and 106.

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, not shown).

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.)

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.

McQuay IM 987 55

Sequences of Operation

Economizer Operation

When the outdoor air is suitable for free cooling, the switch in enthalpy sensor OAE is in position “3” (line 245, Figure 79,

page 71) energizing analog input AIX5. When AIX5

energizes, 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 set point, the economizer is enabled.) If cooling is required, the economizer dampers (ACT3) are modulated to maintain the discharge air temperature setpoint. Analog input AIX5 drives the outdoor air dampers toward the open and closed (line 256) position. If the outdoor air dampers are wide open and more cooling is required, the dampers hold their positions and mechanical cooling is activated (see below).

When the outdoor air is not suitable for free cooling, the switch in enthalpy sensor OAE is in position “1,” de-energizing analog input AIX5. (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.

Heating

Gas Furnace, Super Modulating Burner (20:1 Turndown)

Refer to the Super Mod Gas Furnace Control (1000 MBh) schematic on page page 76 and the Standard Mod, Furnace

Control (1000 MBh) schematic on page page 78 for a

sequence of operation.

56 McQuay IM 987

MicroTech III Controller Opera tion

3/23

System Summary

Advanced Menus Alarm Lists

Unit State= Cooling

Clg Capacity=

25%

1/3McQuay AHU

Enter Password

Continue W/O Password

Version Information

Using the Keypad/Display

The keypad/display consists of a 5-line by 22 character display, three keys and a “push and roll” navigation wheel. There is an Alarm Button, Menu (Home) Button, and a Back Button. The wheel is used to navigate between lines on a screen (page) and to increase and decrease changeable values when editing. Pushing the wheel acts as an Enter Button.

Figure 68: Keypad Controls

MicroTech III Controller Operation

The first line on each page includes the page title and the line number to which the cursor is currently “pointing”. The line numbers are X/Y to indicate line number X of a total of Y lines for that page. The left most position of the title line includes an “up” arrow to indicate there are pages “above” the currently displayed items, a “down” arrow to indicate there are pages “below” the currently displayed items or an “up/down” arrow to indicate there are pages “above and below” the currently displayed page.

Each line on a page can contain status only information or include changeable data fields. When a line contains status only information and the cursor is on that line all but the value field of that line is highlighted meaning the text is white with a black box around it. When the line contains a changeable value and the cursor is at that line, the entire line is highlighted. Each line on a page may also be defined as a “jump” line, meaning pushing the navigation wheel will cause a “jump” to a new page. An arrow is displayed to the far right of the line to indicate it is a “jump” line and the entire line is highlighted when the cursor is on that line.

The keypad/display Information is organized into five main menus or menus groups; Alarm Lists Menu, System Summary Menu, Standard Menus, Extended Menus and Advance Menus.

Note: Only menus and items that are applicable to the specific

unit configuration are displayed.

The Alarm Lists Menu includes active alarm and alarm log information. The System Summary Menu includes status information indicating the current operating condition of the unit. Standard Menus include basic menus and items required to setup the unit for general operation. These include such things are control mode, occupancy mode and heating and cooling setpoints. Extended Menus include more advanced items for “tuning” unit operation such as PI loop parameters and time delays. Advanced Menus include the most advanced

McQuay IM 987 57

items such as “unit configuration” parameters and service related parameters. These generally do not needing changing or accessing unless there is a fundamental change to or a problem with the unit operation.

Passwords

When the keypad/display is first accessed, the Home Key is pressed, the Back Key is pressed multiple times, or if the keypad/display has been idle for the Password Timeout timer (default 10 minutes), the display will show a “main” page where the user can enter a password or continue without entering a password. The three password levels available are Level 2, Level 4, and Level 6, with Level 2 having the highest level of access. Entering the Level 6 password allows access to the Alarm Lists Menu, System Summary Menu, and the Standard Menus group. Entering the Level 4 password allows similar access to Level 6 with the addition of the Extended Menus group. Entering the Level 2 password allows similar access to Level 4 with the addition of the Advanced Menus group. The Level 2 password is 6363, the Level 4 is 2526, and the Level 6 password is 5321. Continuing without entering one of these three levels allows access only to the Alarm Lists Menu and the System Summary Menu.

Note: Alarms can be acknowledged without entering a

password.

Table 13: Password Main Page

MicroTech III Controller Operation

1/1

Enter Password

***

The password field initially has a value **** where each * represents an adjustable field. These values can be changed by entering the Edit Mode described below.

Figure 69: Password Entry Page

Entering an invalid password has the same effect as continuing without entering a password.

Once a valid password has been entered, the controller allows further changes and access without requiring the user to enter a password until either the password timer expires or a different password is entered. The default value for this password timer is 10 minutes. It is changeable from 3 to 30 minutes via the Timer Settings menu in the Extended Menus.

Navigation Mode

In the Navigation Mode, when a line on a page contains no editable fields all but the value field of that line is highlighted meaning the text is white with a black box around it. When the line contains an editable value field the entire line is inverted when the cursor is pointing to that line.

When the navigation wheel is turned clockwise, the cursor moves to the next line (down) on the page. When the wheel is turned counter-clockwise the cursor moves to the previous line (up) on the page. The faster the wheel is turned the faster the cursor moves.

When the Back Button is pressed the display reverts back to the previously displayed page. If the Back button is repeated pressed the display continues to revert one page back along the current navigation path until the “main menu” is reached.

When the Menu (Home) Button is pressed the display reverts to the “main page.”

When the Alarm Button is depressed, the Alarm Lists menu is displayed.

Edit Mode

The Editing Mode is entered by pressing the navigation wheel while the cursor is pointing to a line containing an editable field. Once in the edit mode pressing the wheel again causes the editable field to be highlighted. Turning the wheel clockwise while the editable field is highlighted causes the value to be increased. Turning the wheel counter-clockwise while the editable field is highlighted causes the value to be decreased. The faster the wheel is turned the faster the value is increased or decreased. Pressing the wheel again cause the new value to be saved and the keypad/display to leave the edit mode and return to the navigation mode.

58 McQuay IM 987

Wiring Diagrams

Legend

ID Description Standard location

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

lation damper

ACT6 Actuator motor, return air iso-

lation damper

ACT7 Actuator motor, heat face/by-

pass

ACT8 Actuator motor, cool face/By-

pass

ACT10, 11Actuator motor, exhaust

dampers

ACT12 Actuator motor, enthalpy

wheel bypass damper

AFD10 Adjustable frequency drive,

supply fan

AFD11 Adjustable frequency drive,

evap cond. fans

AFD20 Adjustable frequency drive,

return/exhaust fan

AFD60 Adjust. freq. drive, energy re-

covery wheel(s) AS Airflow switch, burner blower Gas heat box BM Burner blower motor Heat section, gas C10 Power factor capacitors, sup-

ply fan C20 Power factor capacitors, re-

turn fan CB10 Circuit breaker, supply fan Main control box CB11 Circuit breaker, evaporative

condenser fan(s) CB20 Circuit breaker, return/ ex-

haust fan CB60 Circuit breaker, energy recov-

ery wheel CCB1, 2 Compressor control boards,

refrig. circuits CPC Circuit board, main, micro

controller CPR Circuit board, expansion, mi-

cro controller 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/con-

trols DS3 Disconnect, electric heat Electric heat box EAT Exhaust air temperature sen-

sor 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

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

Supply Fan section

Return section

Main/cond. control box

Main control box

Discharge section

Main control box

Energy recovery section

Supply fan section

Wiring Diagrams

ID Description Standard location

F1A, B Fuse, control circuit transform-

er (T1), primary

F1C Fuse, control circuit transform-

er (T1), secondary

F2 Fuse, control circuit transform-

er (T2), primary F3 Fuse, burner blower motor Main control box FB31–40 Fuseblock, electric heat (top

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

bank) 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 GCB1 Generic condenser board, re-

frig. circ. GFR1, 2 Ground fault relay Main control box GFS1, 2 Ground fault sensor Main control box 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 heaters

(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) HP5 Hi-pressure controls, gas Heat section, gas HS1 Heat switch, electric heat

shutdown HS3 Heat switch, electric heat

deadfront interlock HTR65 Heater, sump Evap. condenser section HTR66 Heater, vestibule Evap. condenser vestibule HUM1 Humidstat sensor Energy recovery section IT Ignition transformer Gas heat box LAT Leaving air temperature sen-

sor 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 M10 Contactor, supply fan Main control box M20 Contactor, return fan Main control box M29 Contactor, burner motor Gas heat box M30 Contactor, reversing, invertor

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

bank) M40 Contactor, reversing, Invertor

Bypass, Return Fan

Main control box

Electric heat box

Main control box

Heat section, electric

Main control box

Electric heat box

Energy recovery section

Inv. bypass/main cont. box

Inverter bypass box

Electric heat box

Inverter bypass box

McQuay IM 987 59

Wiring Diagrams

ID Description Standard location

M41–50 Contactor, electric heat (bot.

M60 Contactor, energy recovery

MCB Microprocessor circuit board Main control box MJ Mechanical Jumper All control boxes MMP1–8 Manual motor protector, com-

MMP10 Manual motor protector, sup-

MMP11–18Manual motor protector, cond.

MMP20 Manual motor protector, return

MMP21–28Manual motor protector, cond.

MMP30 Manual motor protector, invrtr.

MMP40 Manual motor protector, invrtr.

MMP51, 52, 53 MMP60 Manual motor protector, ener-

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

PB1, 2 Power block, power distribu-

PB3 Power block, power distribu-

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

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

PM1 Phone modem Main control box PVM1, 2 Phase voltage monitor Main control box R20 Relay, Heat, gas/ steam/ hot

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

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

R26 Relay, isol/exh. dampers,

R28 Relay, isolation damper, safe-tyMain control box

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

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

bank)

wheel

pressors

ply fan

fans, ckt#1

fan

fans, ckt#2

bypass, sup. fan

bypass, ret. fan Manual motor protector, exhaust fan(s)

gy recovery wheel

sor

tion

tion, electric heat

tion

fan

filter

airflow

water

down)

fan inverter

open/close

pass

incr/decr

Electric heat box

Main control box

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

Economizer section

Main control box

Electric heat box

Main control box

Junction box, split unit

Final filter section

Coil section, cool

Gas heat/main cont. box

Gas heat box

Main control box

ID Description Standard location

R48, 49 Relay, return fan inverter, incr/

R58,59 Relay, heat wheel inverter,

R60 Relay, energy recovery wheel,

R61 Relay, smoke detector, dis-

R62, 63, 65Relay, use on specials Main control box

R66 Relay, smoke detector, return

R67 Relay, supply fan, enable Main control box R68 Relay, return fan, enable Main control box R69 Relay, Inv. bypass VAV box in-

R70–79 Relay, use on specials Main control box RAE Return air enthalpy sensor Return section RAT Return air temperature sensor Return section REC1 Receptacle, main box Main control box REC3 Receptacle, field power, 115V Discharge bulkhead REC10–23Receptacle, cabinet sections Cabinet sections

S1 Switch, system on/off Main control box S3 Switch, furnace on/off Gas heat box S4 Switch, inverter bypass, on/ off Main control box S7 Switch, local on/auto/off to

S10–23 Switches, cabinet section

S40–45 Switches, door interlock, UV

SD1 Smoke detector, supply Discharge section SD2 Smoke detector, return Return section SPS1, 2 Static pressure sensors, duct/

SR1-3 Sequencing relays, electric

T1 Transformer, main control

T2 Transformer, control input

T3 Transformer, control output

T4 Transformer, exh. damper ac-

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

T9 Transformer, refrig. circuit 24V Main control box 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 TB7 Terminal block, 115V conve-

TB11 Terminal block, heat Heat control box TB25, 26, 27, 28 TD5–8 Time delay, part winding, com-

TD10 Time delay, hi turn down burn-erGas heat box

decr

incr/decr

enable

charge air

air

terlock

controller

lights

building

heat

(line/115 V (ac)

(115/24 V (ac)

tuator (115/12 V (dc)

troller (115/24 V (ac)

nience outlet, field

Terminal block, split unit junction box

pr #1 - 4

Main control box

Cabinet sections

Main control box

Electric heat box

Main control box

Junction box, split unit

Main control box

60 McQuay IM 987

ID Description Standard location

200/ H200

1. Field wiring

3. Shielded wire/cable

4. Main control box terminals

5. Auxilliary box terminals

6. Field terminals

7. Plug connector

8. Wire/harness number

General Notes

2. Factory wiring

9. Wire nut/ID

WN7

TR1, 2 Transducer, pressure Main control box UV Ultra-violet light(s) Coil/discharge section VM1 Valve motor #1, heating Gas heat box/ heat section VM5 Valve motor #5, cooling Coil section, cool VV1 Vent valve, gas heat Heat Section, Gas ZNT1 Zone temp. sensor, setback Field installed

Wiring Diagrams

McQuay IM 987 61

Wiring Diagrams

ELECTRICAL

CIRCUIT #1

CUSTOMER

SUPPLIED

POWER

T3B

T2B

T1B

T3A

T2A

T1A

GLG1

DS1

(Schematic continues on next page.)

Figure 70: Power Package Only, Main Power

62 McQuay IM 987

Figure 71: Power Package Only, Main Power, Continued

/4.00

/2.00/2.00

HSAF-1

HSAF-2

HSAF-3

HRAF-1

HRAF-2

HRAF-3

426

431

426

108

MTR

T3B

T3A

T2B

T2A

T1B

T1A

L3B

L3A

L2B

L2A

L1B

L1A

T1L1

T3B

T3A

T2B

T2A

T1B

T1A

L3B

L3A

L2B

L2A

L1B

L1A

123

567

GRD

X1X2

T3-1

T2-1

T1-1

T3-3

T2-3

T1-3

T3-5

T2-5

T1-5

SUPPLY-FAN

+NB

MMP10

M10

RETURN-FAN

+NB

M20

MMP20

TB1A TB1A

F1C

F1A

F1B

T1_N

T1_115VAC

DS1

168A

168C

168B

164A

162A

164

162

139

138

137

151

150

149

(Schematic continues on previous page.)

Wiring Diagrams

McQuay IM 987 63

Wiring Diagrams

/1.68 /1.68

H237-3

H265-1

H235-5

H237-4

H265-2

SUPPLY AIR

SMOKE DETEKTOR

(24 VOLT SIGNAL FROM THE FIELD)

H313-1

H313-2

H315-6

H315-8

(CLOSE) (OPEN)

H316-7

(20VA PILOT DUTY MINIMUM CONTACT RATING)

CUSTOMER SUPPLIED POWER

115 VAC

H235-6

H237-5

H267-2

RETURN AIR

SMOKE DETEKTOR

H237-3

H267-1

(24 VOLT SIGNAL FROM THE FIELD)

200

201

202

203

204

205

206

207

208

209

210

211

212

213

214

215

216

217

218

219

220

221

222

223

224

225

226

227

228

229

230

231

232

233

234

235

236

237

238

239

240

241

242

243

219

426221 256

115V

24V

CLASS 2

(ECON/OADM)

1415GRD

101112

114 54

H 115

2-CW

4/R-COM

WHT

1-CCW

BLK

67 68 69

H N

102

56 113 53

H 115

TB1B

T1_115VAC T1_N

TB1B

TB1D

T2_115VAC

TB2

P20

+PP

TB2 TB2

P20

+PP

SD1

+NB

PL11

+PP

PL11

+PP

PL11

+PP

PL11

+PP

ACT3

+NB

PL11

+PP

TB2

GND29

REC1

TB7

TB7 TB7

R63

DHL

TB2 TB2 TB2

SD2

+NB

PL21

+PP

PL21

+PP

204A

204B

203D

168A

168C

228C 228D

227B

239A

238B

238A

201D

201B 201C

219A

228A 228B

227A

(Schematic continues on next page.)

Figure 72: Power Package Only, Control Power

64 McQuay IM 987

Figure 73: Power Package Only, Control Power, Continued

(S.A. FAN AUX CONTACT)

NOTE: THESE CONTACT ARE FOR USE IN A 24 VOLT A.C. CLASS #2 CIRCUIT.

(DUCT HI-LIMIT)

426

219

1413

104108

105106

M10

TB2TB2

R63

TB2TB2

26OA 260B

256A 256B

(Schematic continues on previous page.)

Wiring Diagrams

McQuay IM 987 65

Wiring Diagrams

(Schematic continues on the next page.)

Figure 74: VAV Fan Power (with SAF and RAF VFDs and Manual Bypass)

66 McQuay IM 987

Figure 75: VAV Fan Power (with SAF and RAF VFDs and Manual Bypass), Continued

(Schematic continues on the previous page.)

Wiring Diagrams

McQuay IM 987 67

Wiring Diagrams

)

Figure 76: Constant Volume Fan Power (SAF and RAF)

L3B

L3A

L2B

L2A

L1B

L1A

PB11

SUPPLY-FAN

HSAF-1

MTR

HSAF-2

HSAF-3

DS1

ELECTRICAL

109A

CUSTOMER

CIRCUIT #1

110A

POWER

SUPPLIED

111A

GLG1

M10

MMP10

PB11

T1A

L1A

137A

137

T1L1

426

138A

139A

T3A

T3B

T2A

T2B

T1B

L3B

L3A

L2B

L2A

L1B

139

138

109

L3-3

L2-3

L1-3

(Schematic continues on next page.

426

68 McQuay IM 987

Figure 77: Constant Volume Fan Power (SAF and RAF), Continued

/8.00

/4.00

/3.00

/2.00

/8.00

/2.00

HRAF-1

HRAF-2

HRAF-3

144

145

146

147

148

149

150

151

152

161

162

163

164

165

166

167

168

169

170

109

431

109

426

MTR

X1X2

H3H2

123

567

GRD

L3-1

L2-1

L1-1

T1L1

T3B

T3A

T2B

T2A

T1B

T1A

L3B

L3A

L2B

L2A

L1B

L1A

L3-6

L2-6

L1-6

F1C

F1A

F1B

T1_N

T1_115VAC

TB1A TB1A

PB11

RETURN-FAN

M20

MMP20

PB11

168A

168C

168B

164A

162A

164

162

149

150

151

(Schematic continues on the previous page.)

Wiring Diagrams

McQuay IM 987 69

Wiring Diagrams

(Schematic continues on next page.)

Figure 78: VAV Control Inputs

70 McQuay IM 987

Figure 79: VAV Control Inputs, Continued

Wiring Diagrams

(Schematic continues on previous page.)

McQuay IM 987 71

Wiring Diagrams

/1.68/2.68

/4.00 /4.00

NOTES TO FIELD:

1. ALL FIELD MOUNTED RELAYS

MUST HAVE 24VAC CLASS

2 COILS

THE TOTAL VA OF THE FIELD

MOUNTED RELAYS CAN NOT

EXCEED 15 VA

SOURCE 1-8

WIRED INTERNAL

TO MOTHERBOARD

H313-1

H313-2

H315-6

H315-8

H316-7

300

301

302

303

304

305

306

307

308

309

310

311

312

313

314

315

316

317

318

319

320

321

322

323

324

325

326

327

328

329

330

331

332

333

334

207

364 362

207

239

SRC

(FAN_OPERATION)

(EXT_ALARM_SIGNAL)

BO4

BO3

24V SRC

jprs

24V SRC

jprs

115V

24V

CLASS 2

24V SRC

jprs

(OPEN)

BO6

24V SRC

jprs

(ECON/ACT)

(CLOSE)

BO5

1-8

102

1819 20 21

4NO4

3NO3

117115

116

6NO6

3-CCW

X-COM

2-CW

5NO5

R26

T1_NT2_115VAC

TB1C TB1C

MCB

T3_24V T3_COM

TB2TB2

TB2

PL11

+PP

PL11

+PP

PL11

+PP

PL11

+PP

PL11

+PP

MCB

ACT3

+NB

MCB

307A

305A

303A 303B

318A

315A 315B

168C

203B

(Schematic continues on next page.)

Figure 80: Control Actuator Outputs (CV, Stream, or Hot Water, Plus Economizer)

72 McQuay IM 987

Figure 81: Control Actuator Outputs (CV, Stream, or Hot Water, Plus Economizer), Continued

H365-1

H366-3

H969

H968

H964

H965

H343-5H343-6

H344-7

H343-9

H344-8

338

339

340

341

342

343

344

345

346

347

348

349

350

351

352

353

354

355

356

357

358

359

360

361

362

363

364

365

366

367

368

369

306

207 207

243

RECTIFIER

12V

115V

RELIEF

DAMPER

(OPP.DR

SIDE)

RELIEF

DAMPER

(DRIVE

SIDE)

HEAT

(OPEN)

B10

(CLOSE)

B09

24V SRC

jprs

24V SRC

jprs

BLK

WHT

BLK

5555555

6666666

X-COM

3-CCW2-CW

10NO10 9NO9

RECT

PL17

+PP

ACT11

+NB

ACT10

+NB

R26

TB1F

R26

PL18

+PP

PL18

+PP

PL18

+PP

PL18

+PP

VM1

+NB

MCB M CB

368A

367A

363B

362A 362B

339A 339C

(Schematic continues on previous page.)

Wiring Diagrams

McQuay IM 987 73

Wiring Diagrams

(Schematic continues on next page.)

Figure 82: VFD Control (SAF and RAF)

74 McQuay IM 987

Figure 83: VFD Control (SAF and RAF), Continued

(Schematic continues on previous page.)

Wiring Diagrams

McQuay IM 987 75

Wiring Diagrams

/1.68

H633-9

H632-9

H634-8

NOTE:

1.POWER, PILOT & MAIN VALVE INDICATION

LIGHTS ARE PART OF THE FLAMESAFEGUARD

(FSG) CONTROLLER.

REGULATION AND MANUAL SHUTOFF

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

IS THE SECOND VALVE OF A REDUNDANT

COMBINATION VALVE WITH PRESSURE

IGNITION TRANSFORMER

BLACK BLACK

WHITE

BLACK

WHITE

BLACK

SEE THE PIPING SCHEMATIC BELOW

FOR THE NUMBER OF MAIN GAS VALVES

REQUIRED FOR YOUR BURNER SIZE

H604-3

H604-5

H610-1

H602-2

H603-1

H603-4

H603-2

600

601

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

632

633

634

635

636

(Schematic continues on next page.)

207

628

625

413

625

612

628

627

632628

632615

413

225

402

BO10

BO9

COM

OPEN

MODULATING

GAS & AIR

VALVE

ACTUATOR

(FLOATING)

CCW

(CL)

(OP)

24V SRC

jprs

24V SRC

jprs

6000V

115V

FSG-G

FSG-F

(FLAME ROD)

MICROCOMPUTER

5K12K11K1

(L1)

6K1

3K1

4K1

2K2

FLAME

AMPLI

FIER

FSG

(FLAME SAFEGUARD)

(PLUG-IN TYPE

CONTROLLER)

BLKBLK

10NO10

9NO9

BLK WHT

RED_G630-B WHT_G630-W

YEL_G632-R

YEL_G633-1

YEL_G634-2

NOCOM

2131

COM

C2C1

20202020202020

WHTBLK

107

21212121212121

19191919191919

RED_G617-L WHT_G617-R

RED_G613-L

21 42

RED_G609-L WHT_G609-R

RED_G603-L3

RED_G602-L2

RED_G602-L1

MCB

+MB

PL18

+PP

PL18

+PP

PL19

+PP

TB11

MCB

+MB

VM1

R21

R23

R20

R23

LS1

R22

TD10

R21

ASLS2

R22

R21

R23

GV1A

GV1B

GV4A

GV4B

FSG

TB11

R24

+MB

PL19

+PP

FLC

PL19

+PP

R20

PL19

+PP

R25

+MB

S1/2.01

PL16

+PP

PL19

+PP

SIG_1/4.28

HL22

T1_N

PL19

+PP

PL16

+PP

TB11

634A 634B

633A 633B

632A 632B

631A

621A

628A

621B

621C

617A

613A 613B

611A

610A 610B

607A

604A

604B

603A 603B 603C

602A

201A

426B

168C

Figure 84: Super Mod Gas Furnace Control (1000 MBh)

76 McQuay IM 987

Figure 85: Super Mod Gas Furnace Control (1000 MBh), Continued

OVER 1/2 P.S.I.

SHUTOFF

PIPING DIAGRAM

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

TEST

CONN.

TEST

COCK

SWITCH

AIR

BURNER

BLOWER

MODULATING

ACTUATOR

COCK

GV1B

REG.

HIGH PRESS.

VALVE AND

PRESS. REG.

--MAIN

COMBINATION GAS CONTROLS

GV1A

VALVE AND

--FIRST

MANUAL VALVE.

GV4B GV4A

(TYPICAL)

COCK

GV5B GV5A

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

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

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

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.

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

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

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

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

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),

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

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)

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

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

WHEN 120 VOLT

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

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,

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

(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

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

(Schematic continues on previous page.)

Wiring Diagrams

McQuay IM 987 77

Wiring Diagrams

/1.68

H634-8

H633-9

H632-9

NOTE:

1.POWER, PILOT & MAIN VALVE INDICATION

LIGHTS ARE PART OF THE FLAMESAFEGUARD

(FSG) CONTROLLER.

BLACK WHITE

IGNITION TRANSFORMER

BLACK BLACK

H604-3

H604-5

H610-1

H602-2

H603-1

H603-4

H603-2

600

601

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

632

633

634

635

636

207

625

632

413

225

402

24V SRC

jprs

BO10

24V SRC

jprs

BO9

COM

OPEN

MODULATING

GAS & AIR

VALVE

ACTUATOR

(FLOATING)

CCW

(CL)

(OP)

FSG-G

FSG-F

(FLAME ROD)

MICROCOMPUTER

5K12K11K1

(L1)

6K1

3K1

4K1

2K2

FLAME

AMPLI

FIER

FSG

(FLAME SAFEGUARD)

(PLUG-IN TYPE

CONTROLLER)

6000V

115V

BLKBLK

10NO10

9NO9

RED_G630-B WHT_G630-W

YEL_G632-R

YEL_G633-1

YEL_G634-2

WHTBLK

C2C1

COM

21212121212121

BLK

WHT

BLK

WHT

107

RED_G617-L

202020202020

WHT_G617-R

21 42

RED_G609-L WHT_G609-R

RED_G603-L3

RED_G602-L2

RED_G602-L1

PL19

+PP

PL18

+PP

PL18

+PP

MCB

+MB

MCB

+MB

R23

TB11

VMI

R23

GV1

GV2

GV3

FSG

TB11

R24

+MB

PL19

+PP

FLC

PL19

+PP

R20

PL19

+PP

R25

+MB

S1/2.01

PL16

+PP

PL19

+PP

SIG_1/4.28

HL22

T1_N

PL19

+PP

PL16

+PP

TB11

634B

633C

633B

632B

621B

621C

617A

613A

611A

610A 610B

607A

604A

604B

603A 603B 603C

602A

201A

426B

168C

(Schematic continues on next page.)

624

609

619

618

Figure 86: Standard Mod, Furnace Control (1000 MBh)

78 McQuay IM 987

Figure 87: Standard Mod, Furnace Control (1000 MBh), Continued

PRESS. REG.PRESS. REG.

AIR

SWITCH

AIR

SWITCH

CONN.

TEST

COCK

TEST

CONN.

TEST

COCK

TEST

MAIN GAS VALVES

GV3

PILOT VALVE

MAIN GAS VALVES

GV3

PILOT VALVE

BLOWER

BURNER

BLOWER

BURNER

GV1

CONN.

TEST

GV1

GV2GV2

PIPING DIAGRAMPIPING DIAGRAM

PILOT

REG.

MAIN

PRESS.

PILOT

REG.

MAIN

PRESS.

COCKCOCK

CONN.

TEST

OVER 1/2 P.S.I.

HIGH PRESS.

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

OVER 1/2 P.S.I.

HIGH PRESS.

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

REG.REG.

SHUTOFFSHUTOFF

COCKCOCK

SHUTOFFSHUTOFF

COCKAIR COCK

VALVE

GAS

MOD.

DAMPER

AIR

VALVE

GAS

MOD.

DAMPER

UPON DETECTION OF PILOT FLAME, TERMINAL #10 (IGNITION TRANSFORMER--IT) WILL BE DE-ENERGIZED AND TERMINAL #9 (MAIN GAS VALVES--GV2 & GV3)

THE BURNER COMBUSTION AIR BLOWER MOTOR (BM). WHENEVER POWER IS RESTORED TO THE FLAME SAFEGUARD, THE FLAME SAFEGUARD WILL GO THROUGH A 10 SECOND

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

(BO#9) OR (BO#10) ON THE MAIN CONTROL BOARD (MCB) ARE CLOSED THE ACTUATOR WILL REMAIN AT ITS PRESENT POSITION. THE HEATING CAPACITY IS MONITORED BY THE

POSITION. WHEN THE MAIN CONTROL SYSTEM CLOSES (BO#9) ON THE MAIN CTRL BRD.(MCB), THE ACTUATOR WILL REPOSITION TOWARD A LOWER FIRING RATE. IF NEITHER

MAIN CTRL BRD.(MCB), THE GAS VALVE ACTUATOR WILL REPOSITION TOWARD A HIGHER FIRING RATE UNTIL EITHER (BO#10) OPENS OR THE ACTUATOR REACHES ITS MAXIMUM

GAS VALVE AND COMBUSTION AIR DAMPER AND CAN SET THE FIRING RATE BETWEEN 33% AND 100% OF NORMAL RATE. WHEN THE MAIN CONTROL SYSTEM CLOSES (BO#10) ON THE

WHENEVER THE BURNER IS IN OPERATION ITS FIRING RATE WILL BE DETERMINED BY THE "FLOATING" GAS VALVE ACTUATOR (VM1). THIS ACTUATOR POSITIONS THE BUTTERFLY

MAIN CONTROL BOARD (MCB) THROUGH (AI#10) VIA A POSITION FEEDBACK POTENTIOMETER ON THE ACTUATOR (VM1).

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)

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

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

DE-ENERGIZED, THUS DE-ENERGIZING THE BURNER. THE FLAME SAFEGUARD WOULD THEN BE ON SAFETY LOCKOUT AND WOULD REQUIRE MANUAL RESETTING. THE HEAT ALARM

ALSO, THE FLAME SAFEGUARD CONTAINS "LED'S" (LOWER LEFT CORNER) THAT WILL GLOW TO INDICATE OPERATION.

BLOWER OPERATION IS SENSED BY THE AIR SWITCH (AS), WHICH MAKES TERMINAL #6 TO #7. AFTER A 90 SECOND PREPURGE PERIOD, TERMINAL #8 (FIRST GAS VALVE

THE RELAY DRIVES THE GAS VALVE ACTUATOR (VM1) TO THE MINIMUM FIRING RATE POSITION WHENEVER THE FLAME IS NOT

RELAY (R24) WOULD THEN BE ENERGIZED AND WOULD THEN ENERGIZE THE REMOTE "HEAT FAIL" INDICATOR LIGHT AND SEND A FAIL SIGNAL TO BINARY INPUT #5 ON THE

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

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

INITIATION PERIOD BEFORE THE PREPURGE PERIOD WILL BEGIN.

MICROTECH II MAIN CONTROL BOARD (MCB).

WILL BE ENERGIZED AND THE MAIN FLAME WILL COME ON.

THE FLAME ROD (FD).

(PILOT)--GV1) AND TERMINAL #10 (IGNITION TRANSFORMER--IT) WILL BE ENERGIZED.

ON, AND HOLDS IT THERE UNTIL THE FLAME HAS LIT AND BEEN PROVEN.

LOW FIRE START IS PROVIDED BY RELAY (R23).

SEQUENCE OF OPERATION

THE PILOT FLAME WILL IGNITE AND BE DETECTED BY THE FLAME SAFEGUARD THROUGH

WHEN 120 VOLT

(Schematic continues on the previous page.)

Wiring Diagrams

McQuay IM 987 79

Wiring Diagrams

500

501

502

503

504

505

506

507

508

509

510

511

512

513

514

515

516

517

518

519

520

521

522

523

524

525

526

527

528

529

530

531

532

533

500

546

552

500

548

500

547

500

550

556

500

553

500

554

(MANUAL)

L3B

L3A

L2B

L2A

L1B

L1A

L3-1

L2-1

L1-1

L3-7

L2-7

L1-7

L3-6

L2-6

L1-6

L3-5

L2-5

L1-5

L3-2

L2-2

L1-2

L3-8

L2-8

L1-8

L3-3

L2-3

L1-3

L3-4

L2-4

L1-4

PB3

M31

FB31

HTR1A

HTR3A HTR3B

M43

FB43

PB3

HL12

HTR2B

M42

FB42

PB3

HL11

HTR1B

M41

FB41

PB3

HL4

HTR4A

HL3

HL2

HTR2A

PB3

M32

FB32

HL1

M44

FB44

PB3

M33

FB33

PB3

M34

FB34

HL14

HL13

HTR4B

508A

508B 508C

507C 507D

506C 506D

516D 516E 516F

515E 515F

514E 514F

511G

510G

512D 512E 512F

511E 511F 511H

510E 510F 510H

507G

506G

508D 508E 508F

507E 507F 507H

506E 506F 506H

512B 512C

511C 511D

510C 510D

507B

506B

510A

511A

512A

510B

511B

506A

507A

520D 520E 520F

519E 519F

518E 518F

516B 516C

515C 515D

514C 514D514A

515A

516A

514B

515B

520B 520C

519C 519D

518C 518D518A

519A

520A

518B

519B 519G

518G

515G

514G

(Schematic continues on next page.)

Figure 88: Electric Heat Control

80 McQuay IM 987

Figure 89: Electric Heat Control, Continued

HEATER

BANK "A"

M31

1 A

M32

2 A

M33

3 A

120 KW

HEATER

BANK "B"

M41

1 B

M34

4 A

5 A

6 A

M44

4 B

M43

3 B

M42

2 B

8 B

7 B

120 KW

534

535

536

537

538

539

540

541

542

543

544

545

546

547

548

549

550

551

552

553

554

555

556

557

558

559

560

561

562

563

564

565

566

567

568

569

570

207

506

522

514

506

530

514

522

J10

STAGE 6

STAGE 5

STAGE 4

STAGE 3

STAGE 2

STAGE 1

BO11

SRC

(AUTO)

UNDER HEATER

DEADFRONT

ON SWITCH BRACKET

IN MAIN CONTROL PANEL

NB2

13 12

910

REF

N2-

N2+

24C

BI12

24V

11NO11

A1 A2

9-16

A1 A2

933

171

PL12

+PP

T1_N/1.68

TB11

N2+B/1

NC-B/1

REFB/1

N2+A/1

N2-A/1

REFA/1

T3_COM/3.11T3_24V/3.11

MCB

T3_24V/3.11

M31

PL12

+PP

PL12

+PP

TB11

PL12

+PP

MCB

HL31

M44

HL44

M34

HL34

TB11

PL12

+PP

PL12

+PP

PL12

+PP

M41

M42

M32

M33

M43

HL42

HL41

HL32

HL43

HL33

TB11

PL12

+PP

TB11

PL12

+PP

T1_115VAC/1.68

HS3

HS1

303B

303A

168C

168A

544C

556A

556B 556C

555A

554A

554B 553A

552A

552B 552C

550A

550B 550C

549A

548A

548B 547A

546A

546B 546C

544B

538A

538B

536A 536B

(Schematic continues on previous page.)

HEATER

BANK "A"

M31

1 A

M32

2 A

M33

3 A

120 KW

HEATER

BANK "B"

M41

1 B

M34

4 A

5 A

6 A

M44

4 B

M43

3 B

M42

2 B

8 B

7 B

120 KW

534

535

536

537

538

539

540

541

542

543

544

545

546

547

548

549

550

551

552

553

554

555

556

557

558

559

560

561

562

563

564

565

566

567

568

569

570

207

506

522

514

506

530

514

522

J10

STAGE 6

STAGE 5

STAGE 4

STAGE 3

STAGE 2

STAGE 1

BO11

SRC

(AUTO)

UNDER HEATER

DEADFRONT

ON SWITCH BRACKET

IN MAIN CONTROL PANEL

NB2

13 12

910

REF

N2-

N2+

24C

BI12

24V

11NO11

A1 A2

9-16

A1 A2

933

171

PL12

+PP

T1_N/1.68

TB11

N2+B/1

NC-B/1

REFB/1

N2+A/1

N2-A/1

REFA/1

T3_COM/3.11T3_24V/3.11

MCB

T3_24V/3.11

M31

PL12

+PP

PL12

+PP

TB11

PL12

+PP

MCB

HL31

M44

HL44

M34

HL34

TB11

PL12

+PP

PL12

+PP

PL12

+PP

M41

M42

M32

M33

M43

HL42

HL41

HL32

HL43

HL33

TB11

PL12

+PP

TB11

PL12

+PP

T1_115VAC/1.68

HS3

HS1

303B

303A

168C

168A

544C

556A

556B 556C

555A

554A

554B 553A

552A

552B 552C

550A

550B 550C

549A

548A

548B 547A

546A

546B 546C

544B

538A

538B

536A 536B

(Schematic continues on previous page.)

Wiring Diagrams

McQuay IM 987 81

Wiring Diagrams

433

Figure 90: Fan Control, Power Package Only

82 McQuay IM 987

R63

811

219

/1.68 T1_N115VAC_GF/1

207

SUPPLY FAN ON/OFF

RETURN FAN ON/OFF

TB4

208

TB4

431A

209

MMP20MMP10

426A 426B 426C426D

76757675

149137

TB4

M10

A1 A2

M20

A1 A2

137 260

149

Figure 91: CV Fan Control (SAF and RAF)

401A

404A

426C426B426A

431A

TB2

R68

R67

R68

404

R67

401

M20

A2A1

M10

A2A1

jprs

24V SRC

MCB

2 2NO

BO2

RETURN FAN

207

jprs

24V SRC

MCB

1 1NO

BO1

SUPPLY FAN

207

SRC 9-16

MCB

207

11(31)

MMP10

12(32)

11(31)

MMP20

12(32)

TO MOTHERBOARD

WIRED INTERNAL

SOURCE 9-16

T3_COM

/3.11

T3_24V

/3.11

115VAC_GF/1

T1_N

/1.68

1003B1003A

1004B

1005B1005A

TB7

REC1

CP SL

GRD

SLCP

PL32

S11

PL31

S10

G1004

PL32

G1012

REC11

LT11

BLK WHT

PL31

G1009

REC10

LT10

BLK WHT

FIELD SUPPLIED 115V/60/1

H1010-2H1010-1

H775

H776

H775

H1006-2

H1006-1

H776

H775

Wiring Diagrams

Figure 92: Light and Receptacle Power

McQuay IM 987 83

Unit Options

REC1

FIELD SUPPLIED 115V/60/1

3 5

( 1 . 5 )

4 0

( 4 . 5 )

4 5

( 7 )

5 0

( 1 0 )

6 0

( 1 5 . 5 )

6 5

( 1 8 . 5 )

7 0

( 2 1 )

7 5

( 2 4 )

8 0

( 2 6 . 5 )

8 5

( 2 9 . 5 )

9 0

( 3 2 )

9 5

( 3 5 )

1 0 0

( 3 8 )

1 0 5

( 4 0 . 5 )

5 5

( 1 3 )

1 2

1 4

1 6

1 8

2 0

2 2

2 4

2 6

3 0

3 2

3 4

3 6

3 8

4 0

4 2

4 4

4 6

2 8

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

0 . 5 0

0 . 4 0

0 . 3 0

0 . 2 0

0 . 1 0

0 . 6 0

0 . 7 0

0 . 8 0

0 . 9 0

R E L A T I V E

H U M I D I T Y

3 5

( 1 . 5 )

4 0

( 4 . 5 )

4 5 ( 7 )

5 0

( 1 0 )

5 5

( 1 3 )

6 0

( 1 5 . 5 )

6 5

( 1 8 . 5 )

7 0

( 2 1 )

7 5

( 2 4 )

8 0

( 2 6 . 5 )

8 5

( 2 9 . 5 )

9 0

( 3 2 )

9 5

( 3 5 )

1 0 0

( 3 8 )

1 0 5

( 4

0 . 5 )

Unit Options

Control Actuators

The actuators are controlled by an analog signal from the unit controller. Damper actuators utilize a 0-10 V (dc) analog signal while modulating heating/cooling valve actuators utilize

Figure 93: Control Actuators Wiring Diagram

a 2-10 V (dc) signal. Spring-return actuators are used for the 0

- 30% outdoor air and economizer dampers. The mixing dampers are normally closed to the outside air.

Enthalpy Control

Outside Air Enthalpy Control (OAE)

Units with MicroTech III control and an economizer come standard with an electromechanical enthalpy control device (OAE) that senses both the humidity and temperature of the outside air entering the unit. This device has an enthalpy scale marked A through D. Table 14 shows the control points at 50% RH for settings A through D. Figure 94 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

III controller.

Table 14: Enthalpy Control Settings

Control curve Control point temperature at 50% RH

84 McQuay IM 987

A73°F (23°C) B70°F (21°C) C 67°F (19*C) D63°F (17°C)

Figure 94: Enthalpy Control Settings

Unit Options

Differential Enthalpy Control (OAE/RAE)

An optional electric differential enthalpy control arrangement (OAE/RAE) is available on units with MicroTech III 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 III controller adjusts 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 instantly 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.

Phase Voltage Monitor

The phase voltage monitor (see page 113) protects against high voltage, phase imbalance, and 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.

External Time Clock

You can use an external time clock as an alternative to (or in addition to) the MicroTech III 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 binary input MCB-BI1. This is the normal condition where the controller follows the programmable internal schedule. When the circuit is closed, power is fed to BI1. The MicroTech III controller responds by placing the unit in the occupied mode, overriding any set internal schedule.

For more information, see the “Digital Inputs” section of IM 919, “MicroTech III Applied Rooftop Unit Controller.”

Smoke and Fire Protection

McQuay optionally offers factory installed outdoor air, return air, and exhaust air dampers as well as smoke detectors in the supply and return air openings, complete with wiring and control. These components often are used in the building’s smoke, fume, and fire protection systems. However, due to the wide variation in building design and ambient operating conditions into which our units are applied, we do not represent or warrant that our products will be fit and sufficient for smoke, fume, and fire control purposes. The owner and a fully qualified building designer are responsible for meeting all local and NFPA building code requirements with respect to

smoke, fume, and fire control.

WARNING

Improper smoke, fire, or fume air handling can result in severe personal injury or death.

Smoke Detectors

Field installed smoke detectors in the return air ductwork or the supply air ductwork can be coordinated with the units operation through the unit controller's binary input, D14. This input in wired to TB2 and the supply air smoke detector can be wired between terminals 103 and 104 and the return air smoke detector can be wired between terminals 104 and 105. The T2 transformer supplies 24 V (ac) across each of these terminals and a dry set of contacts can be wired to these terminals respectively. This and additional wiring information can be seen on the input wiring schematics at line number 220.

Figure 95: Smoke Detector Schematic

McQuay IM 987 85

Unit Options

Factory installed smoke detectors have similar wiring and the control sequence is as follows:

When smoke is detected by either sensor, the normally closed sensor contacts open. This removes power from binary input B18 on the main control board.

The Microtech III controller responds by shutting down the unit. 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.

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

Emergency Shutdown

The terminals 105 & 106 on TB2 can be used for any field supplied component that requires a unit emergency shutdown. When these terminals are used, the factory installed jumper must be removed.

Freeze Protection

An optional freezestat is available on units with MicroTech III control that have hot water, chilled water, or 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 III controller takes different actions, depending on whether the fans are on or off. The freezestat is an auto reset type of control; however, the controller alarm that it causes is manually 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 III controller shuts down the fans, closes the outdoor air dampers, opens the heating valve, and sets a 10minute timer. The MicroTech III controller’s active alarm is “Freeze Fault.”

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

The unit remains shut down until the “Freeze Fail” alarm is manually cleared. Refer to the operation manual supplied with the unit for information on clearing alarms (OM138 or OM137).

Fan Off Operation

If the freezestat detects a freezing condition while the fan is off, the MicroTech III controller opens the heating valve and sets a 10-minute timer. The MicroTech III controller’s active alarm is “Freeze Problem.”

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

External Time Clock or Tenant Override

There are several methods of switching the rooftop unit between occupied and unoccupied operation. It can be done by the controller internal schedule, a network schedule, an external time clock, or a tenant override switch.

If the internal schedule or a network schedule is used, field wiring is not required.

An external time clock or a tenant override switch can be used by installing a set of dry contacts across terminals 101 and 102 on the field terminal block (TB2). When these contacts close, 24 V (ac) is applied to binary input MCB-DI3, overriding any internal or network schedule and placing the unit into occupied operation (provided the unit is not manually disabled). When the contacts open (24 V (ac) is removed from MCB-DI3) the unit acts according to the controller internal time schedule or a network schedule. Refer to the unit wiring diagrams for specific wiring termination details.

Figure 96: External Time Clock or Tenant Schematic

86 McQuay IM 987

Unit Options

Field Output Signals

The following outputs may be available for field connections to a suitable device.

VAV Box Signal/Fan Operation Signal

Digital Output #10 (MCB-DO10) may be selected as either the Fan Operation output or the VAV output via the keypad. The VAV/Fan Op selection can be selected by accessing the Unit Setup menu in the Extended Menu section.

Fan Operation

The Fan Operation Output (MCB-DO10) supplies 24 V (ac) to terminal 116 on the field terminal block (TB2) when the output is on. To use this signal, wire the coil of a field supplied and installed 24 V (ac) pilot relay across terminals 116 and 117 on TB2. When this output is on, 24 V (ac) is supplied from the T3 control transformer through the output relay to energize the field relay. Refer to the as-built wiring diagrams.

The Fan Operation output is on when the unit is not Off and when both the unit is Off and airflow is detected. It is off when the unit is off and airflow is not detected.

VAV B ox O u t p ut

The VAV Box Output (MCB-DO10) supplies 24 V (ac) to terminal 116 on the field terminal block (TB2) when the output is on. To use this signal, wire the coil of a field supplied and installed 24 V (ac) pilot relay across terminals 116 and 117 on TB2. When this output is on, 24 V (ac) is supplied from the T3 control transformer through the output relay to energize the field relay. Refer to the as-built wiring diagrams.

In the Heating state, the VAV Output is turned off to indicate that hot air instead of the normal cool air is being supplied to the VAV boxes. The VAV boxes are driven to their Heating Position when hot air is provided based on either the normally open or normally closed contacts of the VAV output. The VFD will continue to be controlled to maintain the desired duct static pressure. This output is also off when the unit is in the Startup or Recirculation states. If this output is in the Heat (off) position when the unit enters the Fan Only state or Minimum DAT Control state, the output remains off for an adjustable Post Heat Time (while the unit VFDs are driven to minimum speed) or until the VFD gets to its minimum speed if the Post Heat Time is set greater than 0. The Post Heat Timer can be adjusted via the keypad/display Timer Setting menu in the Extended Menus.

During unoccupied operation, the VAV Box Output is in the Cool (on) position unless airflow is detected. When airflow is detected, it switches to the Heat (off) position.

Figure 97: Field Output Schematic

Entering Fan Temperature Sensor

The entering fan temperature (EFT) sensor and an associated “Lo Airflow Problem” alarm are provided on VAV units with MicroTech III control and gas or electric heat. The EFT sensor

supply air temperature exceeds the mixed air temperature by more than 60°F (16°C).

Note: This value is not always 60°F. It depends on whether the

unit is gas or electric heat and on the burner/baffling arrangement on gas heat units.

is located in the supply fan section of the unit at the supply air funnel.

In this case, a “Lo Airflow Problem” alarm is generated and heat is not enabled until the alarm is manually cleared. Refer to

Heat is disabled whenever the airflow is detected to be too low for safe heating operation. This condition is indicated when the

the operation manual supplied with the unit for information clearing alarms (OM 920).

McQuay IM 987 87

Unit Options

Duct High Pressure Limit

The duct high pressure limit control (DHL) is provided on all VAV units. The DHL protects the duct work, 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" wc (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 de-energizes. The MicroTech III 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 (OM 920).

Variable Frequency Drive Operation

Refer to the vendor instructions supplied with the unit.

Convenience Receptacle/Section Lights

A Ground Fault Circuit Interrupter (GFCI) convenience receptacle is provided in the main control box on all units. One of the following is required:

1 Connect a separate field-supplied 115 V power wiring

circuit to the 115V field terminal block TB7, located in the main control box.

2 Select the factory powered outlet option at time of

purchase.

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 98).

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 III control panel.

1 Verify that power is supplied to the unit’s MicroTech III

control system. The DesignFlow startup procedure cannot be completed without use of the MicroTech III controls.

2 Unlock and open the louvered outdoor air intake door on

the side of the unit (see Figure 98).

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 98: DesignFlow Station

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 TB7.

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 III 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,

88 McQuay IM 987

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 III 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

Unit Options

D u c t T a p e

V a n e

F u l c r u m

A l i g n m e n t P l a t e

T h i s E d g e F l u s h w i t h B o t t o m o f V a n e

T h e s e E d g e s F l u s h w i t h B o t t o m o f V a n e

D u c t T a p e

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 99) 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.

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 102,

page 90).

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 100, 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 located 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.

Figure 100: Place Leveling Weight On Fulcrum

Figure 99: Tape Fulcrum Alignment Plate to Vane

9 Locate and install the fulcrum used in the leveling

procedure as follows (see Figure 99):

a Wipe the bottom of the louver door where the fulcrum

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

c With the alignment plate taped to the vane and the

McQuay IM 987 89

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

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

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

Unit Options

Top lock nuts

Vane

Bottom lock nut

Pivot point

Louvered door

Access opening

Cover

Threaded adjuster

assembly

Long adjuster nut

Jam nuts

Locknut

To INCREASE L dimension

To INCREASE L dimensi

Right hand adjuster Left hand adjuster

14 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 22.56% to

23.02%, (22.79% is ideal) 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 101). Leveling the unit 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 1/4-20 NC lock nuts at the top of the

DesignFlow frame (see Figure 101).

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 102).

5 Loosen the 1/4-20 NC lock nut in the slotted hole at the

bottom of the DesignFlow frame (see Figure 103).

Figure 102: Remove Covers from Access Opening

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 103.

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 103.

Note: If the necessary adjustment cannot be made using

the long adjuster nut, reposition the two 1/4-20 NC jam nuts on the threaded rod to make larger adjustments (see

When finished making the adjustments, tighten the

Figure 103).

1/4-20 NC lock nut in the slotted hole at the bottom of the DesignFlow frame (see Figure 103).

Figure 103: Leveling Adjustment

Figure 101: DesignFlow Frame

90 McQuay IM 987

Unit Options

Fans and motors

VFD

Starters

A i r f l o w

R o t a t i o n

Note: Make sure the leveling weight’s top thumbscrew is

still against the vertical alignment mark on the vane.

8 Gently rap the base frame to slightly vibrate the

assembly to encourage the vane to seek its equilibrium point.

9 Recheck the vane position compared to the range

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

Note: If large adjustments are required to correctly level

the vane assembly, before rechecking the level, relocate the fulcrum as described in Step 9 in

"DesignFlow Station Startup"‚ page 88.

When the level is correct, unlock and open the louvered outdoor air intake door on the side of the unit and tighten the two 1/4-20 NC lock nuts at the top of the DesignFlow frame (see Figure 101).

Figure 104: Two Fans with Back Return

11 Close and lock the intake door.

12 Recheck the vane position and readjust the level as

necessary.

13 When the vane position is correct, replace the access

opening cover in the louvered door.

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

Prestarting Checks

Figure 105: Fan Rotation

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 105. For three-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.

Once the fan is put into operation, set up a periodic maintenance program to preserve the reliability and performance of the fan. Items to include in this program are:

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.

McQuay IM 987 91

• Belts

• Bearings

• Fasteners

• Setscrews

• Lubrication

• Dust/dirt removal

Unit Options

B e l t S p a n

D e f l e c t i o n =

B e l t S p a n

6 4

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

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

M o t o r

B e a r i n g

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

Belts

Premature belt failures are frequently 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 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 106).

Check belt tension two times during the first 24 hours of operation and periodically thereafter. To adjust belt tension, 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 to adjust the belt.

It is very important that the drive pulleys remain in proper alignment after adjustments are made (see Figure 107). Misalignment of pulleys results in premature belt wear noise,

vibration, and power loss.

WARNING

Rotating parts can cause severe personal injury or death. Replace all belt/fan guards that are removed temporarily for service.

Figure 106: Belt Adjustment

Figure 107: Drive Pulley Alignment

Figure 108: Propeller Exhaust Fan Replacement Parts List

92 McQuay IM 987

Unit Options

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.

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.

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

Thoroughly clean the exterior surface of the motor, fan panel, and entire propeller periodically. Dirt can clog cooling openings on motor housings, contaminate bearing lubricant, and collect on propeller blades causing severe imbalance if left unchecked. 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.

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 does a return fan. They are turned on and off through output MCB-B02 on the Main Control Board. For detailed information on Propeller Exhaust Fan Control, refer to the operation manual supplied with the unit (OM 138 or OM 137).

Lubrication

Refer to “Bearings” above for bearing lubrication. Many fractional horsepower motors installed on the smaller fans are lubricated for life and require no further attention. Motors

Exhaust Fan Troubleshooting

Table 15 provides guidelines for troubleshooting problems

with the propeller exhaust fan options. A list of parts is provided in Figure 108, page 92.

equipped with oil holes should be oiled in accordance with the

Table 15: Propeller Exhaust Fan Troubleshooting

Problem Cause Corrective Action

Reduced

Airflow

Excessive

Noise

System resistance is too high.

Unit running backwards. See “Prestarting Checks” on page 101 Fan speed too low. Increase fan speed Excessive dirt on propeller. Clean propeller Bearings Tighten bearing collars and setscrews. Lubricate bearings. Replace defective bearings. V-Belt drive Tighten pulleys on motor shaft and fan shaft. Adjust belt tension. Align pulleys. Replace worn belts or pulleys. Excessive vibration Clean dirt build-up from propeller. Check all setscrews and fasteners for tightness. Check for worn bearing.

Defective motor Replace motor.

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.

Correct propeller imbalance. Check for loose dampers, guards or ductwork.

McQuay IM 987 93

Unit Options

Ultraviolet

Light Units

Light Power Disconnect Switch

View Window

Cooling Coil

AIRFLOW

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.

WARNING

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 109: Typical Ultraviolet Light Installation

94 McQuay IM 987

Ultraviolet Light Operation

Refer to the wiring schematic below. 115 V (ac) 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. To 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 24 V (ac) 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 115 V (ac) to the UV lights.

Figure 110: Typical Ultraviolet Light Wiring Schematic

Unit Options

McQuay IM 987 95

Check, Test, and Start Procedures

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, complete and sign the check, test, and start form supplied with the unit, or complete the "Rooftop Equipment Warranty Regist. Form"‚

page 118 and return it to McQuay International.

WARNING

Electric shock and moving machinery hazard. Can cause severe equipment damage, personal injury, or death. Disconnect and tag out all electrical power before servicing this equipment. All start-up and service work must be performed only by trained, experienced technicians familiar with the hazards of working on this type of equipment. Read and follow this manual: “MicroTech III Applied Rooftop Unit Controller” (OM 920) before operating or servicing. Bond the equipment frame to the building electrical ground through grounding terminal or other approved means.

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 113 for instructions.

Servicing Control Panel Components

WARNING

Hazardous voltage. May cause severe injury or death. Disconnect electric power before servicing equipment. More than one disconnect may be required to de-energize the unit.

Disconnect all electric power to the unit when servicing control panel components. Unless power is disconnected to the unit, the components are energized. Always inspect units for multiple disconnects to ensure all power is removed from the control panel and its components before servicing.

Before Start-up

1 Verify that the unit is completely and properly installed

with ductwork connected.

2 Verify that all construction debris is removed, and that

the filters are clean.

3 Verify that all electrical work is complete and properly

terminated.

4 Verify that all electrical connections in the unit control

panel and compressor terminal box are tight, and that the proper voltage is connected.

5 Verify all nameplate electrical data is compatible with

the power supply.

6 Verify the phase voltage imbalance is no greater than

10%.

7 Verify that gas piping is complete and leak tight.

8 Verify that the shutoff cock is installed ahead of the

furnace, and that all air has been bled from the gas lines.

9 Manually rotate all fans and verify that they rotate freely.

10 Verify that the belts are tight and the sheaves are aligned.

11 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.

12 Verify that the evaporator condensate drain is trapped

and that the drain pan is level.

13 If unit is curb mounted, verify that the curb is properly

flashed to prevent water leakage.

14 Before attempting to operate the unit, review the control

layout description to become familiar with the control locations.

15 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.

16 Determine which optional unit controls are included.

17 Before closing (connecting) the power disconnect

switch, 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 Furnace Control Compartment

– Turn furnace switch S3 to OFF.

– Main Control Panel Switch

18 If the DAC or SCC unit does not have an optional zone

S7 to OFF.

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.

Note: If desired, you can significantly reduce all MicroTech III

internal control timers by the 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 the unit to operate with fast timers.

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 circuit transformer (T1).

2 Turn the Switch S1 to ON. Power should now be

supplied to the control panel, and the LEDs on MCB1 should follow the normal startup sequence (refer to

"Power-up"‚ page 55).

96 McQuay IM 987

Check, Test, and Start Procedures

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. If the fan does not run:

a Check fuses F1 and F3.

b Check the manual motor protectors or that the circuit

breakers have not tripped.

c Check the optional phase monitor.

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 "Spring

Isolated Fans"‚ page 52.

5 Verify the fan rotation is correct.

6 Verify the DHL safety is opening at a pressure

compatible with duct working pressure limits.

Note: The supply and return fan drives usually are 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 98.

Economizer Start-up

CAUTION

Adjust dampers properly. Improper adjustment can damage the dampers.

When an economizer is ordered without an actuator, the linkage requires a 3.14" linear stroke to open it fully. 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 Temperature\OA Damper\OA Ambient=. Low indicates low outdoor air

enthalpy; High indicates high outdoor air enthalpy. See

"Enthalpy Control"‚ page 84 to verify that the enthalpy

changeover control is working properly. You may want to take temperature and humidity measurements.

2 At the keypad, set the cooling setpoint low enough so the

controller calls for cooling. Adjust the value in Temperature\Zone Cooling\Occ Clg Spt= below the temperature shown in Temperature\Zone Cooling\Control Temp=. In addition, on DAC units, adjust the value in Temperature\Discharge Cooling\DAT

Clg Spt= below the temperature shown in Temperature\Discharge Cooling\Disch Air=.

3 Place the unit into cooling mode through the keypad

menu System Summary\System\Ctrl Mode= Cool Only.

4 Observe the outdoor air dampers:

d If the outdoor enthalpy is low, the control algorithm

should start to modulate the dampers open to maintain the discharge air setpoint.

e If the outdoor enthalpy is high, the dampers should

maintain their minimum position. Look at menu Temperature\OA Damper\MinOA Pos=. Change this entry to another value. Verify that the dampers move to the new minimum position setpoint.

5 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 MicroTech III 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 4a. If it is High, go to Step 4b.

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.

Perform the following procedure on all units:

1 At the keypad, set the cooling setpoint low enough so

that the controller will call for cooling. The value in Temperature \ 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 Close the S1 switch. Now cooling is enabled and circuit

#2 is disabled. After CS1 is closed, the MT III board starts its 5-minute timing cycle. 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 cooling.

4 When the outdoor air damper has fully opened and the

time delay has expired, the chilled water valve will open.

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.

McQuay IM 987 97

Check, Test, and Start Procedures

Heating System Startup

General

1 At the keypad, set the heating setpoints high enough so

that the controller calls for heating.Adjust the value in Temperature \ Zone Heating \ Occ Htg Spt= above the temperature shown in Temperature \ Zone Heating \ Control Temp=. In addition, on DAC units, adjust the value in Temperature \ Discharge Heating \ DAT Htg

Spt= 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 Verify 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=).

Gas Furnace

Refer to the “Start-up and Operating Procedures” section of the Forced Draft Gas Fired Furnace Installation Manual, IM 684 or IM 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 III 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 100. The return fan motors are usually

shipped with fixed pitch sheaves.

WARNING

Moving machinery hazard. Can cause severe personal injury or death. Do not use a mechanically driven tachometer to measure the speed of return fans on this fan arrangement. Use a strobe tachometer.

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.

3 For VAV units that have fan tracking control, adjust the

supply/return fan balance by using the MicroTech III controller's built-in, automatic capability. For complete information on using this feature, see OM 920 “MicroTech III® Unit Controller for Applied Rooftop and Self-Contained Systems”

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.

WARNING

Rotating parts can cause severe personal injury or death. Replace all belt/fan guards that are temporarily removed for service.

98 McQuay IM 987

Check, Test, and Start Procedures

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

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

M o t o r

B e a r i n g

B e l t S p a n

D e f l e c t i o n =

B e l t S p a n

6 4

Sheave Alignment

Mounting:

1 Verify 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 ce1nter line of the driven sheave. See Figure 111.

2 Verify that all setscrews are torqued to the values shown

in Table 23, page 109 before starting drive. Check setscrew torque and belt tension after 24 hours of service.

Figure 111: Sheave Alignment (Adjustable Shown)

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 Measurement Procedure

1 Measure the belt span. See Figure 112.

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 on the drive kit label

found on the fan housing.

Figure 112: Drive Belt Adjustment

McQuay IM 987 99

Check, Test, and Start Procedures

T w o G r o o v e

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 .

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 .

Mounting and Adjusting Motor Sheaves

VM and VP Variable Pitch Sheaves

Mounting:

Adjusting:

1 Mount all sheaves on the motor shaft with setscrew A

toward the motor (see Figure 113, page 100).

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.

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 113,

page 100). 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.

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.

Figure 113: VM and VP Variable Pitch Sheaves

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 5, page 101). 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 5, page 101).

2 To 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 twogroove 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.

100 McQuay IM 987

McQuay RAH 047C, RAH 077C, RDS 800C, RDS 802C Maintenance Manual

Specifications and Main Features

Frequently Asked Questions

User Manual