Installation and Maintenance Manual IM 970-1
Maverick™ I
Commercial Packaged Rooftop Systems
Heating & Cooling
Models MPS003B – 005B
3 to 5 Tons
R-410A Refrigerant
Group: Applied Air Systems
Part Number: IM 970-1
Date: July 2010
© 2010 McQuay International
®
Contents
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Checking Product Received. . . . . . . . . . . . . . . . . 3
Safety Information . . . . . . . . . . . . . . . . . . 3
Major Components. . . . . . . . . . . . . . . . . . . . . . . . 3
Mechanical Installation . . . . . . . . . . . . . . . . . . . . . . 4
General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Pre-Installation Check-Points . . . . . . . . . . . . . 4
Location Considerations . . . . . . . . . . . . . . . . . 4
Outside Slab Installation . . . . . . . . . . . . . . . . . 5
Attaching Exhaust and Combustion Air Inlet
Hoods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Cover Panel Installation/Conversion. . . . . . . . 5
Clearances . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Rooftop Installation . . . . . . . . . . . . . . . . . . . . . 6
Ductwork. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Return Air . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Rigging and Roofcurb . . . . . . . . . . . . . . . . . . . 7
Gas Supply, Condensate Drain and Piping. . . 8
Adjusting or Checking Furnace Input . . . . . . . 9
Electrical Installation . . . . . . . . . . . . . . . . . . . . . . 11
Wiring. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Power Supply . . . . . . . . . . . . . . . . . . . . . . . . 11
Hook-Up . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Internal Wiring. . . . . . . . . . . . . . . . . . . . . . . . 12
Customer Supplied Thermostat . . . . . . . . . . 13
Optional Factory Supplied Thermostat . . . . . 13
Wiring Diagrams. . . . . . . . . . . . . . . . . . . . . . . . . 14
Physical Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Unit Capacity and Physical Data . . . . . . . . . . . . 24
Electrical Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Motor Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
MCA and MCOP Data . . . . . . . . . . . . . . . . . . . . 25
Dimensional Data . . . . . . . . . . . . . . . . . . . . . . . . . 26
Unit Dimensions MPS 003B – 005B. . . . . . . . . . 26
Curb Dimensions . . . . . . . . . . . . . . . . . . . . . . . . 29
Performance Data . . . . . . . . . . . . . . . . . . . . . . . . . 30
Airflow Performance . . . . . . . . . . . . . . . . . . . . . 30
Accessories. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Economizers . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Economizers: 3–5 Tons [10.6–17.6 kW]. . . . 32
Fresh Air Dampers and Power Exhaust . . . . . . 34
Integral Power Exhaust For Economizer: 3–5
Tons [10.6–17.6 Kw] (Field Installed Only). . 34
Fresh Air Damper Kit for 3–5 Ton
[10.6–17.6 Kw] Units . . . . . . . . . . . . . . . . . . 34
Roofcurbs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Roofcurbs (Full Perimeter): 3–5 Tons
[10.6–17.6 kW] . . . . . . . . . . . . . . . . . . . . . . . 35
Controls and Operation . . . . . . . . . . . . . . . . . . . . 36
Furnace Section Controls and Ignition System . 36
Normal Furnace Operating Sequence . . . . . 36
Operating Instructions . . . . . . . . . . . . . . . . . 36
Burners. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Manual Reset Overtemperature Control. . . . 37
Pressure Switch . . . . . . . . . . . . . . . . . . . . . . 37
Limit Control . . . . . . . . . . . . . . . . . . . . . . . . . 37
Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Advise The Customer. . . . . . . . . . . . . . . . . . 38
Unit Maintenance. . . . . . . . . . . . . . . . . . . . . . . . 38
Furnace Section . . . . . . . . . . . . . . . . . . . . . . 38
Lubrication . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Cooling Section Maintenance. . . . . . . . . . . . 39
System Charge Charts . . . . . . . . . . . . . . . . . . . 40
Blower Motor Speed Taps . . . . . . . . . . . . . . 43
Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . 45
Cooling Troubleshooting Chart . . . . . . . . . . . . . 45
Furnace Troubleshooting Guide . . . . . . . . . . . . 46
Warranty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
Replacement Parts . . . . . . . . . . . . . . . . . . . . . . 48
Introduction
General
This manual contains the installation and operating
instructions for your packaged rooftop unit. There are some
precautions that should be taken to derive maximum
satisfaction from it. Improper installation can result in
unsatisfactory operation or dangerous conditions.
Introduction
WARNING
Install this unit only in a location and position as specified in
the “Mechanical Installation” section of these instructions.
Provide adequate combustion and ventilation air to the unit
space as specified in the venting section of these instructions.
Read this manual and any instructions packaged with separate
equipment prior to installation. Give this manual to the owner
and explain its provisions. The owner should retain this
manual for future reference.
This product line does have an optional DDC controller. For
operation and information on using and programming the
MicroTech II unit controller, refer to the appropriate operation
manual (see Table 1).
For a description of operation and information on using the
keypad to view data and set parameters, refer to the
appropriate program-specific operation manual (see Table 1).
Table 1: Operation, Installation and Maintenance
Resources
Unit Manual
Rooftop unit control configuration
DDC Unit Controller OM 1077
BACnet Communication Module IM 1000
LonWorks Communication Module IM 999
Operation manual bulletin
number
Checking Product Received
Upon receiving the unit, inspect for any damage from
shipment. Claims for damage, either shipping or concealed,
should be filed immediately with the shipping company.
IMPORTANT: Check the unit model number, heating size,
electrical characteristics, and accessories to determine if they
are correct.
Safety Information
DANGER
WARNING
Combustion products must be discharged outdoors. Connect
this unit to an approved vent system only, as specified in
“Mechanical Installation” section of these instructions.
WARNING
Use only with type of gas approved for this unit. Refer to the
unit rating plate.
DANGER
Never test for gas leaks with an open flame. It can cause an
explosion or fire resulting in property damage, personal injury
or death. Use a commercially available soap solution made
specifically for the detection of leaks to check all connections,
as specified in the “Mechanical Installation” section of these
instructions.
WARNING
Always install unit to operate within the unit's intended
temperature-rise range with a duct system which has an
external static pressure within the allowable range, as
specified in the “Mechanical Installation” section of these
instructions. See also unit rating plate.
DANGER
Units are not design certified to be installed inside the
structure. Doing so can cause inadequate unit performance
as well as property damage and carbon monoxide poisoning
resulting in personal injury or death.
The manufacturer’s warranty does not cover any damage or
defect to the air conditioner caused by the attachment or use
of any components, accessories or devices (other than those
authorized by the manufacturer) into, onto, or in conjunction
with the air conditioner. you should be aware that the use of
unauthorized components, accessories or devices may
adversely affect the operation of the air conditioner and may
also endanger life and property. The manufacturer disclaims
any responsibility for such loss or injury resulting from the use
of such unauthorized components, accessories or devices.
Major Components
The unit includes a hermetically-sealed refrigerating system
(consisting of a scroll compressor, condenser coil, and
evaporator coil with a thermal expansion valve), a circulation
air blower, and a condenser fan. The cooling system of these
units is factory-evacuated, charged and performance tested.
Refrigerant amount and type are indicated on rating plate.
Heat options include natural gas fired furnace or a field
installed electric resistance heater. The furnace assembly
WARNING
Provide adequate combustion and ventilation air to the unit
space as specified in the combustion and ventilation air
section of these instructions.
McQuay IM 970-1 3
comes complete including a heat exchanger assembly, gas
burner and control assembly, combustion air motor and fan,
and all necessary internal electrical wiring.
Mechanical Installation
Mechanical Installation
General
WARNING
When a unit is installed so that supply ducts carry air
circulated by the unit to areas outside the space containing
the unit, the return air shall also be handled by duct(s) sealed
to the unit casing and terminating outside the space
containing the unit.
Install this unit in accordance with The American National
Standard Z223.1-latest edition manual entitled “National Fuel
Gas Code,” and the requirements or codes of the local utility or
other authority having jurisdiction.
Additional helpful publications available from the “National
Fire Protection Association” are: sNFPA-90A - Installation of
Air Conditioning and Ventilating Systems 1985 or latest
edition. NFPA-90B - Warm Air Heating and Air Conditioning
Systems 1984.
These publications are available from:
National Fire Protection Association, Inc.
Batterymarch Park
Quincy, MA 02269
Pre-Installation Check-Points
1 Before attempting any installation, carefully consider the
following points:
a Structural strength of supporting members (rooftop
installation)
b Clearances and provision fo r servi cing power supply
and wiring
c Gas supply and piping
d Air duct connections and sizing
e Drain facilities and connections
f Location for minimum noise and vibration - away
from bedroom windows
Location Considerations
The metal parts of this unit may be subject to rust or
deterioration in adverse environmental conditions. This
oxidation could shorten the equipment’s useful life. Salt spray,
fog or mist in seacoast areas, sulphur or chlorine from lawn
watering systems, and various chemical contaminants from
industries such as paper mills and petroleum refineries are
especially corrosive.
If the unit is to be installed in an area where contaminants are
likely to be a problem, give special attention to the equipment
location and exposure.
1 Avoid having lawn sprinkler heads spray directly on the
unit cabinet.
2 In coastal areas, locate the unit on the side of the building
away from the waterfront.
3 Shielding by a fence or shrubs may give some protection.
4 Frequent washing of the cabinet, fan blade and coil with
fresh water will remove most of the salt or other
contaminants that build up on the unit.
5 Regular cleaning and waxing of the cabinet with a good
automobile polish will provide some protection.
6 A good liquid cleaner may be used several times a year
to remove matter that will not wash off with water.
Several different types of protective coatings are offered in
some areas. These coatings may provide some benefit, but the
effectiveness of such coating materials cannot be verified by
the equipment manufacturer.
The best protection is frequent cleaning, maintenance, and
minimal exposure to contaminants.
WARNING
This unit may be used to heat the building or structure during
construction if the following installation requirements are met.
Installation must comply with all install ation instructions
including:
• Proper vent installation
• Furnace operating under thermostatic control
• Return air duct sealed to the furnace
• Air filters in place
• Set furnace input rate and temperature rise per rating plate
marking
• Means of providing outdoor air required for combustion
• Return air temperature maintained between 55°F (13°C )
and 80°F (27°C)
• Installation of exhaust and combustion air inl e t hoods
completed
• Clean furnace, duct work and components upon
substantial completion of the construction process, and
verify furnace operating conditions including ignition,
input rate, temperature rise and venting, according to the
instructions.
4 McQuay IM 970-1
Mechanical Installation
Outside Slab Installation
DANGER
These units are designed certified for outdoor installation
only. Installation inside any part of a structure can result in
inadequate unit performance as well as property damage.
Installation inside can also cause recirculation of flue
products into the conditioned space resulting in personal
injury or death.
Typical outdoor slab installation is shown in Figure 1.
1 Select a location where external water drainage cannot
collect around unit.
2 Provide a level slab sufficiently high enough above grade
to prevent surface water from entering the unit
3 The location of the unit should be such as to provide
proper access for inspection and servicing as shown in
Figure 3, page 6.
4 Locate unit where operating sounds will not disturb
owner or neighbors.
Figure 1: Outside Slab Installation
obstructions such as weeds, shrubs, vines, snow, etc.
Inform the user accordingly.
8 Remove compressor shipping supports (if so equipped)
after installation.
Attaching Exhaust and Combustion Air Inlet Hoods
IMPORTANT: Do not operate this unit without the exhaust/
combustion air inlet hood properly installed. This hood is
shipped in a carton in the blower compartment inside the unit
and must be attached when the unit is installed. See Figure 30.
To attach exhaust/combustion air inlet hood:
1 Remove screws securing blower access panel and
remove access panel. For location of blower access
panel, see Figure 29, page 26 .
2 Remove exhaust/combustion air inlet hood from the
carton, located inside the blower compartment.
3 Attach blower access panel.
4 Attach the combustion air inlet/exhaust hood with
screws. Reference Figure 30, page 27 for proper
location. Screws are in carton with the hood.
5 Vent the unit using the flue exhaust hood, as supplied
from the factory, without alteration or addition.
Locate unit so roof runoff water does not pour directly on
5
the unit. Provide gutter or other shielding at roof level.
Do not locate unit in an area where excessive snow
drifting may occur or accumulate.
6 Where snowfall is anticipated, the height of the unit
above the ground level must be considered. Mount unit
high enough to be above anticipated maximum area
snowfall and to allow combustion air to enter the
combustion air inlet.
7 Select an area which will keep the areas of the vent, air
intake, and A/C condenser fins free and clear of
Cover Panel Installation/Conversion
Downflow To Horizontal
1 Remove the screws and covers from the outside of the
supply and return sections.
2 Install the covers in the bottom supply and return
openings with the painted side up (Figu re 2). Use the
existing gasket to seal the covers.
3 Secure the supply cover to the base of the unit with one
screw, engaging prepunched tab in unit base.
4 Secure the return cover to the base of the unit with
screws engaging prepunched holes in the unit base.
Figure 2: Cover Gasket Detail–Down-Flow to Horizontal
This unit is provided with 2 - 25” × 16” × 1” disposable filters.
When replacing filters, ensure they are inserted fully to the
back to prevent bypass.
McQuay IM 970-1 5
Mechanical Installation
Clearances
The following minimum clearances (Table 2) must be
observed for proper unit performance and serviceability (also
reference Figure 3).
Table 2: Recommended Clearances
Location Clearance
A - Front 48"
B - Condenser Coil 18"
C - Duct Side 12"*
D - Evaporator End 36"
E - Above 60"
Note: *Without Ec onomizer. 57 With
Economizer
Note: Supply duct may be installed with 0" clearance to
combustible materials, provided 1" minimum Fiberglass
insulation is applied either inside or outside of the duct.
Rooftop Installation
1 Before locating the unit on the roof, make sure that the
roof structure is adequate to support the weight involved
(see Unit Capacity and Physical Data‚ page 24). THIS
IS VERY IMPORTANT AND THE INSTALLER’S
RESPONSIBILITY.
2 For rigging and roofcurb details, see Figure 5, Figure 6
and Figure 7.
3 The location of the unit on the roof should be such as to
provide proper access for inspection and servicing.
Ductwork
The installing contractor should fabricate ductwork in
accordance with local codes. Use industry manuals as a guide
when sizing and designing the duct system. Contact Air
Conditioning Contractors of America, 1513 16th St. N.W.,
Washington, D.C. 20036.
DANGER
Never connect return ductwork to any other heat producing
device such as fireplace insert, stove, etc. Unauthorized use
of such devices may result in fire, carbon monoxide
poisoning, explosion, personal injury, property damage or
death.
Place the unit as close to the conditioned space as possible
allowing clearances as indicated. Run ducts as directly as
possible to supply and return outlets. Use of non-flammable
weatherproof flexible connectors on both supply and return
connections at unit to reduce noise transmission is
recommended.
Figure 4: Unit Mounted on Roofcurb
Figure 3: Clearances
4
Remove compressor shipping supports (if so equipped)
after installation.
IMPORTANT: If unit will not be put into service
immediately, block off supply and return air openings to
prevent excessive condensation.
On ductwork exposed to outside temperature and humidity, use
a minimum of 2" of insulation and a vapor barrier. Distribution
system in attic, furred space or crawl space should be insulated
with at least 2" of insulation. 1/2" to 1" thick insulation is
usually sufficient for ductwork inside the air conditioned
space.
Provide balancing dampers for each branch duct in the supply
system. Properly support ductwork from the structure.
6 McQuay IM 970-1
Mechanical Installation
N
A
*
E
T
D
Return Air
IMPORTANT: In the event that the return air ducts must be
run through an “unconfined” space containing other fuel
burning equipment, it is imperative that the user be informed
against future changes in construction which might change this
to a “confined space.” Also, caution the user against any future
installation of additional equipment (such as power ventilators,
clothes dryers, etc.) within the existing unconfined and/or
confined space which might create a negative pressure within
the vicinity of other solid, liquid, or gas fueled units.
DANGER
Never allow products of combustion or the flue products to
enter the return air ductwork or the circulating air supply. All
return ductwork must be adequately sealed and secured to
the furnace with sheet metal screws and joints must be taped.
All other duct joints must be secured with approved
connections and sealed airtight.
Failure to prevent products of combustion from being
circulated into the living space can create potentially
hazardous conditions, including carbon monoxide poisoning
that could result in personal injury or death.
Figure 6: Roofcurb
HOLD
DOWN
BRACKET
TYP. (4) PLCS.
GASKET
(FULL PERIMETER
AND ON DIVIDERS,
MUST BE ABOVE DUCT
AND INSULATION
PANEL FLANGES.)
INSULATION PANELS
(2) SUPPLIED
NAILING STRIP
SUPPLY DUCT
*
RETURN DUCT
UNIT
SUPPLY
RETURN
*
ST-A0801-19-01
Rigging and Roofcurb
Figure 5: Rigging Detail
Figure 7: Roofcurb Detail
ROOFTOP UNIT
ROOFTOP U
GASKET
GASKET
NAILER STRIP
NAILER STRIP
DUCT*
DUCT*
ROOFCURB
ROOFCURB
ROOF
STRUCTURAL
TURAL
MEMBER*
ER*
*BY CONTRACTOR
COUNTER FLASHING*
COUNTER FL
INSULATION*
INSULATION
CANT STRIP*
CANT STRIP*
ROOF FELT*
ROOF F
INSULATION*
INSULA
ROOF DECK*
ROOF
McQuay IM 970-1 7
Mechanical Installation
Gas Supply, Condensate Drain and Piping
Gas Connection
IMPORTANT: Connect this unit only to gas supplied by a
commercial utility.
1 Install gas piping in accordance with local codes and
regulations of the local utility company. In the absence
of local codes, the installation must conform to the
specifications of the National Fuel Gas Code, ANSI
Z223. 1 - latest edition.
Note: The use of flexible gas connectors is not permitted.
Connect the gas line to the gas pipe inlet opening
2
provided into the 1/2" inlet valve. See Figure 1, page 5 or
Figure 4, page 6 for typical piping.
3 Size the gas line to the furnace adequate enough to
prevent undue pressure drop and never less than 1/2".
4 Install a drip leg or sediment trap in the gas supply line
as close to the unit as possible.
5 Install an outside ground joint union to connect the gas
supply to the control assembly at the burner tray.
6 Gas valves have been factory installed. Install a manual
gas valve where local codes specify a shut-off valve
outside the unit casing (see Figure 8).
Note: The Commonwealth of Massachusetts requires the gas
shut-off valve to be a T-handle gas lock.
7 Make sure piping is tight. A pipe compound resistant
to the action of liquefied petroleum gases must be
used at all threaded pipe connections.
IMPORTANT: any additions, changes or conversions
required for the furnace to satisfactorily meet the application
should be made by a qualified installer, service agency or the
gas supplier, using factory-specified or approved parts. In the
commonwealth of Massachusetts, installation must be
performed by a licensed plumber or gas fitter for appropriate
fuel.
IMPORTANT: Disconnect the furnace and its individual
shutoff valve from the gas supply piping during any pressure
testing of that system at test pressures in excess of 1/2 pound
per square inch gauge or isolate the system from the gas
supply piping system by closing its individual manual shutoff
valve during any pressure testing of this gas supply system at
pressures equal to or less than 1/2 PSIG.
DANGER
IMPORTANT: Check the rating plate to make certain the unit
is equipped to burn the type of gas supplied. Care should be
taken after installation of th is equipment that the gas control
valve not be subjected to high gas supply line pressure.
Figure 8: Suggested Gas Piping
ROOF OR GROUND LEVEL INSTALLATION
FROM GAS
METER
MANUAL GAS
SHUT-OFF
VALVE
Factory supplied grommet must be utilized.
*
Table 3: Gas Pipe Capacity Table (Cu. Ft./Hr.)
Nominal
Iron Pipe
Size
1/2” 132 92 73 63 56 50 46 43
3/4” 278 190 152 130 115 105 96 90
1” 520 350 285 245 215 195 180 170
1-1/4” 1,050 730 590 500 440 400 370 350
1-1/2” 1,600 1,100 890 760 670 610 560 530
10 20 30 40 50 60 70 80
Equivalent Length of Pipe, Feet
UNIT GAS SUPPLY
CONNECTION
*
In making gas connections, avoid strains as they may cause
noise and damage the controls. A backup wrench is required to
be used on the valve to avoid damage.
The capacities of gas pipe of different diameters and lengths in
cu. ft. per hr. with pressure drop of 0.3 in. and specific gravity
of 0.60 (natural gas) are shown in Table 3.
After determining the pipe length, select the pipe size which
will provide the minimum cubic feet per hour required for the
gas input rating of the furnace. By formula:
Gas Input of Furnace
(BTU/Hr.)
Cu. Ft. Per Hr. Required =
_________________
Heating Value of Gas
(BTU/Ft.)
The gas input of the furnace is marked on the furnace rating
plate. The heating value of the gas (BTU/FT3) may be
determined by consulting the local natural gas utility or the
L.P. gas supplier.
Never test for gas leaks with an open flame. It can cause an
explosion or fire resulting in property damage, personal injury
or death. Use a commercially available soap solution made
specifically for the detection of leaks to check all connections,
as specified in the “Mechanical Installation” section of these
instructions.
8 McQuay IM 970-1
Mechanical Installation
LP Conversion
DANGER
This unit is equipped at the factory for use with natural gas
only. Conversion to LP gas requires a special kit supplied by
the distributor or manufacturer. Mailing addresses are listed
on the furnace rating plate, parts list and warranty. Failure to
use the proper conversion kit can cause fire, carbon
monoxide poisoning, explosion, personal injury, property
damage, or death.
Convert the valve to use liquefied petroleum (LP) gas by
replacing the pressure regulator spring with the conversion kit
spring. This LP kit spring allows the regulator to maintain the
proper manifold pressure for LP gas. The correct burner LP
orifices are included in the kit. See Figure 9, page 9.
IMPORTANT: To remove the gas valve, remove the four
screws securing the manifold pipe to the burner tray. Remove
the manifold pipe with gas valve attached. See Figure 10.
Note: Order the correct LP conversion kit from the furnace
manufacturer. See Conversion Kit Index shipped with
unit for proper LP kit number. Furnace conversion to LP
gas must be performed by a qualified technician.
Figure 9: NOx Inserts
Figure 10: Manifold Pipe
NOx Models
When converting units equipped with NOx inserts to LP gas,
the stainless steel screen mesh inserts in the entrance of the
tubular exchangers are not required to meet SCAQMD NOx
emission levels. These inserts and 1/8" diameter retaining rod
should be carefully removed before firing this furnace on LP
gas. IMPORTANT: This furnace is not designed to operate on
LP gas with the NOx inserts in place.
Step by step instructions on removing the NOx inserts and
retaining rod are included in the Conversion Kit Installation
Instructions.
Table 4: LP Gas Pipe Capacity Table (Cu. Ft./Hr.)
MANIFOLD PIPE
Adjusting or Checking Furnace Input
• Natural Gas Line Pressure 5" - 10.5" W.C.
• LP Gas Line Pressure 11" - 13" W.C.
• Natural Gas Manifold Pressure 3.5" W.C
• LP Gas Manifold Pressure - 10" W.C.
Supply and manifold pressure taps are located on the gas valve
body 1/8" N.P.T. and on the manifold.
Use a properly calibrated manometer gauge for accurate gas
pressure readings.
Only small variations in the gas flow should be made by
means of the pressure regulator adjustment. Furnaces
functioning on LP gas must be set by means of the tank or
branch supply regulators. The furnace manifold pressure
should be set at 10" W.C. at the gas control valve.
McQuay IM 970-1 9
Mechanical Installation
To adjust the pressure regulator, remove the regulator cap and
turn the adjustment screw clockwise to increase pressure or
counterclockwise to decrease pressure. Then replace the
regulator cap securely.
Any necessary major changes in the gas flow rate should be
made by changing the size of the burner orifices. To change
orifice spuds, shut off the manual main gas valve and remove
the gas manifold.
For elevations up to 2,000 feet, rating plate input ratings apply.
For high altitudes (elevations over 2,000 ft.), contact McQuay
Parts.
Check of input is important to prevent over-firing of the
furnace beyond its design-rated input. NEVER SET
INPUT ABOVE THAT SHOWN ON THE RATING
PLATE. Use the following table or formula to determine
input rate.
Heating Value of Gas
(BTU/Cu. Ft.) x 3600
Cu. Ft. Per Hr. Required =
_________________
Time in Seconds
(for 1 Cu. Ft.) of Gas
Start the furnace and measure the time required to burn one
cubic foot of gas. Prior to checking the furnace input, make
certain that all other gas units are shut off, with the exception
of pilot burners. Time the meter with only the furnace in
operation.
Table 5: Meter Times
Meter time, in minutes and seconds, for normal input
rating of furnaces equipped for natural or LP gas
Input
BTU/hr
40,000
60,000
80,000
100,000
Meter Size
Cu.Ft.
1 1:21 1:30 1:34 1:39 3:45
10 13:30 15:00 15:36 16:30 37:30
1 0:54 1:00 1:03 1:06 2:30
10 9:00 10:00 10:24 11:00 25:00
1 0:41 0:45 0:47 0:50 1:53
10 6:45 7:30 7:48 8:15 18:45
1 0:33 0:36 0:38 0:40 1:30
10 5:24 6:00 6:15 6:36 15:00
Heating value of gas BTU per cu. ft.
900 1000 1040 1100 2500
IMPORTANT NOTICE: Derating of the heating input for
high altitude in the field is unlawful in Canada (refer to CAN/
CGA 2.17). Units installed in altitudes greater than 2,000 feet
(610 meters) must be shipped from the factory or from a
factory authorized conversion station with the heating input
derated by 10% so as to operate properly in altitudes from
2,000 - 4,500 feet (610 - 1,373 meters).Condensate Drain
The condensate drain connection of the evaporator is threaded
3/4" nominal P.V.C. pipe. Install a condensate trap to ensure
proper condensate drainage (Figure 11)
Figure 11: Condensate Drain
IMPORTANT NOTE FOR ALTITUDES ABOVE 2,000
FEET (610 METERS): The main burner orifices in your
furnace and in these kits are sized for the nameplate input and
intended for installations at elevations up to 2,000 feet in the
USA or Canada, or for elevations of 2,000 - 4,500 feet (610 1,373 meters) in Canada if the unit has been derated at the
factory. For elevations above 2,000 feet (610 meters) IN THE
USA ONLY (see ANSI-Z223.1), the burner orifices must be
sized to reduce the input 4% for each 1,000 feet (305 meters)
above sea level.
10 McQuay IM 970-1
Electrical Installation
Electrical Installation
Wiring
Power Supply
DANGER
Power supply to the unit must be disconnected before making
field connections. To avoid electrical shock, personal injury or
death, be sure to rigorously adhere to field wiring procedures
regarding proper lockout and tagout of components.
1 All wiring should be made in accordance with the
National Electrical Code. Consult the local power
company to determine the availability of sufficient
power to operate the unit. Check the voltage at power
supply to make sure it corresponds to the unit’s RATED
VOLTAGE REQUIREMENT. Install a branch circuit
disconnect (refer to Figure 12 and Figure 13) near the
rooftop, in accordance with the N.E.C., C.E.C. or local
codes. A bracket is provided with the unit for mounting
of the disconnect.
2 It is important that proper electrical power is available at
the unit. Voltage should not vary more than 10% from
that stamped on the unit nameplate. On three phase units,
phases must be balanced within 3%.
3 For branch circuit wiring (main power supply to unit
disconnect), the minimum wire size for the length of run
can be determined from Figure 14 using the circuit
ampacity found on the unit rating plate. Use the smallest
wire size allowable from the unit disconnect to the unit.
4 For through the base wiring entry, all fittings and conduit
are field supplied for this application (Figure 15,
page 12). Reference T able 6, page 12 for proper hole and
conduit size.
Figure 12: Recommended Branch Circuit Disconnect
Location – Gas Heat Units
Figure 13: Recommended Location of Branch Circuit
Disconnect –Electric Heat or Cooling Only Units
TO POWER
BRANCH CIRCUIT DISCONNECT
TO CONTROL
Figure 14: Branch Circuit Copper Wire Size (Based on 1%
Voltage Drop)*
Note:
1
Wire size based on 60°C rated wire insulation and 30°C
ambient temp. (86°F).
2 For more than 3 conductors in a raceway or cable, see the
N.E.C. for derating the ampacity of each conductor.
When installed, the unit must be electrically grounded in
accordance with local codes or, in the absence of local codes,
with the National Electrical Code, ANSI/NFPA 70, if an
external electrical source is utilized.
IMPORTANT: THIS UNIT IS APPROVED FOR USE
WITH COPPER CONDUCTORS ONLY
CONNECTED
TO UNIT CONTACTOR.
WARRANTY MAY BE JEOPARDIZED IF ALUMINUM
WIRE IS CONNECTED TO UNIT CONTACTOR.
Special instructions apply for power wiring with aluminum
conductors: Warranty is void if connections are not made
per instructions.
Attach a length (6" or more) of recommended size copper wire
to the unit contactor terminals L1 and L3 for single phase, L1,
L2 and L3 for three phase.
BRANCH
CIRCUIT
DISCONNECT
TO POWER
TO THERMOSTAT
Select the equivalent aluminum wire size from the tabulation
below:
Splice copper wire pigtails to aluminum wire with U.L.
recognized connectors for copper-aluminum splices. Please
exercise the following instructions very carefully to obtain a
positive and lasting connection:
McQuay IM 970-1 11
Electrical Installation
1 Strip insulation from aluminum conductor. 2 Coat the stripped end of the aluminum wire with the
recommended inhibitor, and wire brush the aluminum
AWG Copper
Wire Size
#12 #10 T & B Wire Nut PT2
#10 # 8 T & B Wire Nut PT3
# 8 # 6 Sherman Split Bolt TSP6
# 6 # 4 Sherman Split Bolt TSP4
# 4 # 2 Sherman Split Bolt TSP2
Figure 15: Electrical Conduit Installatio n
AWG Aluminum
Wire Size
Connector Type and Size
(or equivalent)
surface through inhibitor. INHIBIT ORS: Brundy-Pentex
“A”; Alcoa-No. 2EJC; T & B-KPOR Shield.
3 Clean and re-coat aluminum conductor with inhibitor.
4 Make the splice using the above listed wire nuts or split
bolt connectors.
5 Coat the entire connection with inhibitor and wrap with
electrical insulating tape.
Table 6: Recommended Wire Sizes For Given Conduit and Hole Size
Wire Size, AWG 14 12 10 8 6 4 3 2 1 0 00 000
Conduit Size
Hole Size
Hook-Up
To wire unit, refer to the following hook-up diagram. Refer to
Figure 28, page 26 and Figure 15, page 12 for location of
1/2” 1/2” 1/2” 3/4” 1” 1” 1-1/4” 1-1/4” 1-1/2” 1-1/2” 2” 2”
7/8” 7/8” 7/8” 1-31/32” 1-23/64” 1-23/64” 1-23/32” 1-23/32” 1-31/32” 1-31/32” 2-15/32” 2-15/32”
limitation for Type T wire [63°F rise (35°C)] when installed in
accordance with the manufacturer’s instructions.
Internal Wiring
wiring entrances.
IMPORTANT: Some single phase units are equipped with a
Wiring to be done in the field between the unit and devices not
attached to the unit, or between separate devices which are
field installed and located, shall conform with the temperature
12 McQuay IM 970-1
single pole contactor. Caution must be exercised when
servicing as only one leg of the power supply is broken with
the contactor.
Electrical Installation
Some models are equipped with electronically commutated
blower motors which are constantly energized, unless the main
unit disconnect is in the off position.
A diagram of the internal wiring of this unit is located under
the electrical box cover and this manual. If any of the original
wire as supplied with the unit must be replaced, the wire gauge
thermostat is adaptable to most residential 24 volt forced air
multi-stage systems with electric or fossil fuel auxiliary and is
the ultimate for comfort, convenience, and performance. See
Figure 18, page 14 for an optional factory supplied thermostat
wiring diagram.
Figure 16: Optional Thermostat
and insulation must be same as original wiring.
Transformer is factory wired for 230 volts on 208/230 volt
models and must be changed for 208 volt applications. See
unit wiring diagram for 208 volt wiring.
Customer Supplied Thermostat
The customer supplied room thermostat must be compatible
with the spark ignition control on the unit. Generally, all
thermostats that are not of the “current robbing” type are
compatible with the integrated furnace control. The low
voltage wiring should be sized as shown below.
FIELD WIRE SIZE FOR 24 VOLT THERMOSTAT CIRCUITS
SOLID COPPER WIRE - AWG.
3.0 16 14 12 10 10 10
2.5 16 14 12 12 12 10
2.0 18 16 14 12 12 10
50 100 150 200 250 300
Length of Run – Feet
a
Table 7: Optional Factory Supplied Thermostat
Specifications
a. The total wire length is the distance from the furnace
to the thermostat and back to the furnace.
Note: Do not use control wiring smaller than No. 18 AWG.
Install the room thermostat in accordance with the instruction
sheet packed in the box with the thermostat. See Figure 17,
page 14 for an example of a typical customer supplied wiring
diagram.
Optional Factory Supplied Thermostat
The optional factory supplied, touch screen, commercial
setback digital thermostat (Figure 16) uses microcomputer
technology to provide precise time and temperature control.
This thermostat offers the flexibility to design heating and
cooling programs that fit building needs (Table 7). This
Table 8: Thermostat Terminal Functions
Y2 2nd Stage Compressor
Y Compressor Relay
G Fan Relay
RC Power for Cooling
RH Power for Heating
C
L Malfunction indicator for systems with malfunction connection
W/E Heat Relay/Emergency Heat Relay (Stage 1)
W2 2nd Stage Heat (3rd Stage Heat in HP2)
Blank Blank
- Common (DC) for wired remote temperature sensor
S Frequency signal from remote temperature senso r
+ Power (DC) to remote temperature sensor
Common wire from secondary side of cooling (Optional). Required for fault
indication, continuous backlight operation or remote temperature sensor operation
Electrical Rating Single
Stage:
Electrical Rating Staging:
Terminal Load:
Setpoint Range:
Anticipation, Heating:
Anticipation, Cooling:
Rated Differential Single
Stage:
Rated Differential Staging:
Operating Ambient:
Operating Humidity
Shipping Temperature
Range:
Dimensions (H x W x D):
mV to 30 V (ac), NEC Class II, 50/60 Hz
or DC
20 to 30 V (ac), NEC Class II
1.5 A per terminal, 2.5 A max. combined
45° to 99°F (7° to 37°C)
Adjustable
Adjustable
Heat 0.6°F, Cool 1.2°F
Heat 0.6°F, Cool 1.2°F
32° to +105°F (0° to +41°C)
90% non-condensing max.
-4° to 150°F (-20° to 65°C)
4.6” x 5.9” x 1.2”
McQuay IM 970-1 13
Electrical Installation
Wiring Diagrams
Figure 17: Typical Customer Supplied Thermostat Wiring Diagram
Figure 18: Optional Factory Supplied 7-170 Thermostat Wiring Diagram
Y2
Orange
Yellow
Green
Red
Brown
+
S
-
W2
W/E
6
L
Black
Black
C Y1GW2W1R Y2
Terminal Block
1) On 3 to 5 ton units, a terminal block is not supplied. Use a wirenut to extend from the leads provided in the unit to the thermostat.
W1, W2, and Y2 are optional depending upon the size and selected options of the unit. Colors shown above are typical for the MPS I.
2) For wiring with DDC control option, see OM 1077 for wiring instructions.
14 McQuay IM 970-1
Figure 19: Wiring Diagram: MPS 003B to 004B, 208/230 Volt
Electrical Installation
McQuay IM 970-1 15
Electrical Installation
Figure 20: Wiring Diagram: MPS 003B to 004B, 460 Volt
16 McQuay IM 970-1
Figure 21: Wiring Diagram: MPS 003B to 004B with Gas Heat
Electrical Installation
McQuay IM 970-1 17
Electrical Installation
Figure 22: MPS003B-MPS005B, 208-230/460V, 3Ø, Gas Heat
DDC
Controller
18 McQuay IM 970-1
Figure 23: MPS003B-MPS005B, 208-230/460V, 3Ø, Cooling Only
Electrical Installation
DDC
Controller
McQuay IM 970-1 19
Electrical Installation
Figure 24: Wiring Diagram: MPS 005B
20 McQuay IM 970-1
Figure 25: Wiring Diagram: MPS 005B with Gas Heat, 208/230 Volt, Belt Drive
Electrical Installation
McQuay IM 970-1 21
Electrical Installation
Figure 26: Wiring Diagram: MPS 005B with Gas Heat, 208/230 Volt, Direct Drive
22 McQuay IM 970-1
Figure 27: Wiring Diagram: MPS 005B with Gas Heat, 460 Volt, Belt Drive
Electrical Installation
McQuay IM 970-1 23
Physical Data
Physical Data
Unit Capacity and Physical Data
Table 9: MPS 003B – 005B
Model
Cooling Performance
Gross cooling BTU [kW] 36,800 [10.78] 50,000 [14.65] 61,000 [17.87]
EER/SEER
Nominal airflow/ARI airflow (cfm) [L/s] 1200 [566] 1600 [755] 2000 [944]
Net cooling BTU [kw] 35,400 [10.37] 48,000 [14.06] 59,000 [17.29]
Net sensible BTU [kW] 26,200 [7.68] 35,600 [10.43] 42,000 [12.31]
Net latent BTU [kW] 9200 [2.7] 12,400 [3.63] 17,000 [4.98]
Net system power kW 3.1 4.19 5.32
Compressor(s)
Type/number Scroll/1 Scroll/1 Scroll/1
Gas Heating Performance
AFUE % 808080
Steady stage efficiency % 81 81 81
No. stages 1 1 1
Gas connection size 1/2" 1/2" 1/2"
Heating input (BtuH) 80,000/120,000 80,000/135,000 100,000/135,000
Heating output (BtuH) 64,800/97,200 64,800/109,400 81,000/109,400
Temperature rise °F 30 - 80 30 - 80 25 - 70
Sound
Outdoor rating (dB) 78 78 83
Outdoor Coil
Fin type Louvered Louvered Louvered
Tube type Rifled Rifled Rifled
Tube size OD (in.) [mm] 3/8 [9.5] 3/8 [9.5] 3/8 [9.5]
Face area (sq. ft) [sq. m] 16.91 [1.57] 16.56 [1.54] 16.56 [1.54]
Rows (fpi) [fpcm] 1/22 [9] 2/22 [9] 2/22 [9]
Indoor Coil
Fin type Corrugated Corrugated Corrugated
Tube type Rifled Rifled Rifled
Tube size OD (in.) [mm] 3/8 [9.5] 3/8 [9.5] 3/8 [9.5]
Face area (sq. ft) [sq. m] 5.17 [0.48] 5.17 [0.48] 5.17 [0.48]
Rows (fpi) [fpcm] 2/17 [7] 3/15 [6] 3/16 [6]
Refrigerant control TX valves TX valves TX valves
Drain connection (in.) [mm] 3/4 [19.00] 3/4 [19.0] 1 [19.05]
Condenser Fan
Type Propeller Propeller Propeller
No. used/diameter (in.) [mm] 1/24 [609.6] 1/24 [609.6] 1/24 [609.6]
Drive type/No. of speeds Direct/1 Direct/1 Direct/1
CFM [L/s] 3680 [1737] 3680 [1737] 3680 [1737]
Motor hp 1/3 1/3 1/3
Motor rpm 1075 1075 1075
Indoor Fan
Type FC Centrifugal FC Centrifugal FC Centrifugal
No. used/diameter (in.) [mm] 1/10x10 [254x254] 1/10x10 [254x254] 1/10x10 [254x254]
No. motors 1 1 1
Motor hp 1/2 - 3/4 1/2 - 3/4 3/4 - 1
Motor rpm 1075 1075 1725
Filter
Fin type Disposable Disposable Disposable
Furnished Yes Yes Yes
No. size (in.) [mm]
Refrigerant
Charge oz. [g] 96 [2722] 165 [4678] 160 [4536]
Weight
Net weight lbs. [kg] 543 [246] 580 [263] 597 [271]
Shipping weight lbs. [kg] 550 [249] 587 [266] 604 [274]
2
4
1
3
003B 004B 005B
11.4/13 11.45/13 11.1/13
(2) 1x16x24
[25x406x635]
MPS
(2) 1x16x24
[25x406x635]
(2) 1x16x24
[25x406x635]
24 McQuay IM 970-1
Electrical Data
Electrical Data
Motor Data
Table 10: Compressor and Condenser Motor Data – 208/230 Volt
Electrical Data (208/230 V)* Electrical Data (460 V)* Electrical Data (575 V)*
Data
Compressor Motor
No. 1 1 1
Phase 3 3 3
RPM 3450 3450 3450
HP, Compressor 1 345345345
Amps (RLA), Comp. 1 10.4 13.7 15.6 5.8 6.2 7.5 3.8 4.8 5.8
Amps (LRA), Comp. 1 88 83.1 110 38 41 52 36.5 33 38.9
HP, Compressor 2 N/A N/A N/A N/A N/A N/A N/A N/A N/A
Amps (RLA), Comp. 2 N/A N/A N/A N/A N/A N/A N/A N/A N/A
Amps (LRA), Comp. 2 N/A N/A N/A N/A N/A N/A N/A N/A N/A
Condenser Motor
No. 1 1 1
Phase 1 1 1
HP 1/3 1/3 1/3
Amps (FLA, each) 1.2/1.2 1.4 1.0
Amps (LRA, each) 4.7/4.7 2.4 1.8
Note: *Unit operating voltage range is 187 - 253 for 208/230V; 414 - 506 for 460V; 518 - 632 for 575 V.
MPS
003B
MPS
004B
MPS
005B
MPS
003B
MPS
004B
MPS
005B
MPS
003B
MPS
004B
MPS
005B
MCA and MCOP Data
Table 11: Unit MCA and MCOP Data
Vol tag e
MPS Model
003B
004B
005B
Note: *Low static option is a direct drive motor for models 003B and 004B.
MCA 19.0 N/A 11.0 N/A N/A N/A
MCOP 25.0 N/A 15.0 N/A N/A N/A
MCA 23.0 N/A 11.0 N/A N/A N/A
MCOP 35.0 N/A 15.0 N/A N/A N/A
MCA N/A 26.0 N/A 13.0 N/A 10.0
MCOP N/A 30.0 N/A 20.0 N/A 15.0
208/230 460 575
Low* High Low* High Low* High
McQuay IM 970-1 25
Dimensional Data
Dimensional Data
Unit Dimensions MPS 003B – 005B
Figure 28: Bottom View
FLUE OUTLET (GAS
HEATING UNITS ONLY)
4.625
SUPPLY AIR
2.25
2
9.56
44.125
RETURN AIR
4.5
2
13.125
20
3.25
4.5
Figure 29: Cabinet Dimensions and Access Locations
31.19
20
13.125
14.44
2
Important: This unit must
be mounted level in both
directions to allow water to
48.125
drain from the condenser
section and condensate
pan.
I316
COIL/FILTER
ACCESS
BLOWER
ACCESS
3.81
5.34
SUPPLY COVER
RETURN COVER
78.25
48.06
24.03
26 McQuay IM 970-1
Figure 30: Cabinet Dimensions and Access Locations – Gas Heat Units
Dimensional Data
McQuay IM 970-1 27
Dimensional Data
Figure 31: Unit Dimensions
31.22
3.81
COIL/FILTER
ACCESS
BLOWER
ACCESS
5.34
SUPPLY COVER
RETURN COVER/
OPTIONAL OUTDOOR
AIR HOOD LOCATION
76.31
Figure 32: Supply and Return Dimensions – Back View
24
47.09
CONDENSATE DRAIN
3/4” NPT FEMALE
28 McQuay IM 970-1
Curb Dimensions
Figure 33: MPS 003B – 005B Curb Dimensions
Dimensional Data
McQuay IM 970-1 29
Performance Data
Performance Data
Airflow Performance
Figure 34: Airflow Performance—MPS 003B–004B, 208V, 230V, 460V
0.8 [.20]
0.7 [.17]
0.6 [.15]
925 [437]
360
1180 [557]
445
1280 [604]
555
1375 [649]
410
1100 [519]
925 [437]
360
1180 [557]
445
515
1280 [604]
545
515
0.8 [.20]
1100 [519]
0.7 [.17]
410
1230 [580]
475
475
1230 [580]
555
1375 [649]
0.8 [.20]
1100 [519]
0.7 [.17]
1210 [571]
0.6 [.15]
410
475
1230 [580]
555
1375 [649]
600
635
410
1100 [519]
425
475
1230 [580]
505
555
1375 [649]
0.5 [.12]
CFM 1685 [795] 1620 [765] 1580 [746] 1550 [732] 1500 [708] 1430 [675] 1350 [637]
Watts 635 600 580 570 550 535 505
700 660 635 600
740
760
780
CFM 1870 [883] 1830 [864] 1790 [845] 1730 [816] 1660 [783] 1580 [746] 1500 [708]
Watts
0.4 [.10] 0.5 [.12]
External Static Pressure—Inches W.C. [kPa]
CFM [L/s] Air Delivery/RPM/Watts—208 Volts
0.3 [.07]
400 395 385 380 375 370
0.2 [.05]
0.1 [.02]
1210 [571] 1193 [563] 1175 [555] 1155 [545] 1125 [531] 1075 [507] 1015 [479]
CFM
450
Watts
1515 [715] 1500 [708] 1475 [696] 1450 [684] 1405 [663] 1350 [637] 1275 [602]
CFM
Watts 525 515 510 505 490 475 460
CFM 1680 [793] 1650 [779] 1625 [767] 1580 [746] 1530 [722] 1460 [689] 1390 [656]
Watts 650 640 630 610 580 560 545
CFM 1210 [571] 1193 [563] 1175 [555] 1155 [545] 1125 [531] 1075 [507] 1015 [479]
450 400 395 385 380 375 370
Watts
1500 [708] 1475 [696] 1450 [684] 1405 [663] 1350 [637] 1275 [602]
1515 [715]
CFM
525 515 510 505 490 475 460
Watts
CFM 1680 [793] 1650 [779] 1625 [767] 1580 [746] 1530 [722] 1460 [689] 1390 [656]
630 610 580 560
640
650
Watts
CFM [L/s] Air Delivery/RPM/Watts—230 Volts
External Static Pressure—Inches W.C. [kPa]
0.1 [.02] 0.2 [.05] 0.3 [.07] 0.4 [.10] 0.5 [.12] 0.6 [.15]
1335 [630] 1305 [616] 1255 [592] 1210 [571]
1360 [642]
1375 [649]
470 460 455 450 440 435 425
1400 [661]
CFM
Watts
CFM 1400 [661] 1375 [649] 1360 [642] 1335 [630] 1305 [616] 1255 [592] 1210 [571]
Watts 470 460 455 450 440 435 425
570 550 535 505
1550 [732] 1500 [708] 1430 [675] 1350 [637]
580
1580 [746]
600
1620 [765]
635
CFM 1685 [795]
Watts
760 740 700 660 635 600
CFM 1870 [883] 1830 [864] 1790 [845] 1730 [816] 1660 [783] 1580 [746] 1500 [708]
Watts 780
CFM [L/s] Air Delivery/RPM/Watts—460 Volts
External Static Pressure—Inches W.C. [kPa]
0.3 [.07] 0.4 [.10]
0.2 [.05]
0.1 [.02]
CFM 1400 [661] 1375 [649] 1360 [642] 1335 [630] 1305 [616] 1255 [592]
Watts 470 460 455 450 440 435 425
CFM 1685 [795] 1620 [765] 1580 [746] 1550 [732] 1500 [708] 1430 [675] 1350 [637]
Watts 635 600 580 570 550 535 505
1730 [816] 1660 [783] 1580 [746] 1500 [708]
1790 [845]
1830 [864]
780 760 740 700 660
CFM 1870 [883]
Watts
450 440 435
470 460 455
CFM 1400 [661] 1375 [649] 1360 [642] 1335 [630] 1305 [616] 1255 [592] 1210 [571]
Watts
570 550 535
635 600 580
CFM 1685 [795] 1620 [765] 1580 [746] 1550 [732] 1500 [708] 1430 [675] 1350 [637]
Watts
780 760 740 700 660 635 600
CFM 1870 [883] 1830 [864] 1790 [845] 1730 [816] 1660 [783] 1580 [746] 1500 [708]
Watts
DIRECT- DRIVE 208 AIRFLOW PERFORMANCE
Motor
Speed
Motor
HP [w]
Blower Size/
Manufacturer
Recommended
Air-Flow Range
Input
BTU/hr
Heating
Motor Speed
From Factory
Unit Model
# of Speeds
(Min/Max) CFM
[kW]
Cool Heat
Model MPS-
Low
80,000
[23.45]
Low
10x10
120,000
Med
1/2 HP [373]
[35.17]
Med
Low 1050/1350
003
3 Speed Motor
High
Low
10x10
100,000
Med
1/2 HP [373]
1400/1800
[29.31]
Med
004 Med
3 Speed Motor
High
[39.56]
135,000
High
[] Designates Metric Conversions
Motor
Speed
Motor
HP [w]
# of Speeds
Blower Size/
Manufacturer
Recommended
Air-Flow Range
(Min/Max) CFM
[kW]
Input
BTU/hr
Heating
Heat
Motor Speed
From Factory
Cool
MPS-
Unit Model
Low
80,000
[23.45]
Low
Med
10x10
1/2 HP [373]
3 Speed Motor
[35.17]
120,000
Med
003 Low 1050/1350
High
Low
80,000
[23.45]
Low
Med
10x10
1/2 HP [373]
3 Speed Motor
[29.31]
100,000
Med
004 Med 1400/1800
High
[39.56]
135,000
High
Motor
Speed
Motor
HP [w]
# of Speeds
Blower Size/
Manufacturer
Recommended
Air-Flow Range
(Min/Max) CFM
[kW]
Input
BTU/hr
Heating
Heat
Motor Speed
From Factory
Cool
MPS-
Unit Model
80,000
[23.45]
Low
120,000
Low
10x10
1/2 HP [373]
1050/1350
[35.17]
003 Low
Med
High
3 Speed Motor
Low
Med
10x10
1/2 HP [373]
3 Speed Motor
1400/1800
004 High
High
[29.31]
100,000
High
[39.56]
135,000
[ ] Designates Metric Conversions
30 McQuay IM 970-1
Figure 35: Airflow Performance—MPS 005B, 208V, 230V, 460V
—
—
Performance Data
1.5 [.37]
RPM W
1.4 [.35]
1.3 [.32]
1.2 [.30]
1.1 [.27]
W RPM W RPM W RPM W RPM W
1.0 [.25]
RPM
0.9 [.22]
0.8 [.20]
RPM W RPM W
W
1215 700 1255 735 1320 775 1355 805
675
595 1080 615 1135 650 1165
1045
1100 760 1140 785 1175 810 1225 850 1260 880 1320 930 1365 985 1390 1020
710
1290 960 1335 1000 1375 1050 1405 1100
915
850 1200 890 1245
1160
810
1120
950 1210 995 1250 1020 1290 1060 1335 1100 1370 1150 1400 1200 — —
1170
— —
1195 1020 1240 1055 1275 1100 1320 1140 1360 1180 1385 1225 — —
980
—
—
—
1405 1320
1260
1375
1230
1350
1175
1125 1310
1225 1095 1265
—
—
—
— — — —
—
—
1305 1270 1360 1350 1400 1395
0.7 [.17]
RPM
External Static Pressure—Inches of Water [kPa]
W
0.6 [.15]
RPM
0.5 [.12]
0.4 [.10]
0.3 [.07]
RPM W RPM W RPM W
W
0.2 [.05]
W RPM
Capacity 5 Ton [17.6 kW]
Voltage 208/230-460—3 Phase
0.1 [.02]
RPM
Air
Flow
CFM [L/s]
1400 [661] — — — — 780 370 815 385 875 425 930 460 970 490 1030 540 1065 570 1105 595 1150 615 1195 645 1235 660 1300 705 1340 745
415 895 440 945 500 995 540
840
795 405
—
1500 [708] — — —
510 965 560 1015 600 1060 640 1105 680 1145 705 1180 730 1225 750 1275 790 1340 840 1365 880
425 870 470 915
805
780 390
1600 [755] — —
1700 [802] — — 795 450 840 490 895 530 940 570 990 605 1035 640 1075 680 1120 725 1160 755 1200 790 1245 815 1300 855 1355 905 1375 940
540 915 560 965 615 1010 660 1055
870
815 470
1800 [850] 780 455
720 1070 775
1035
675
590 945 640 995
895
850 530
1900 [897] 800 485
655 970 700 1015 730 1055 790 1105 830 1145 875 1180 910 1225 950 1260 980 1320 1035 1350 1075 1385 1120 — —
930
2000 [944] 830 550 880 605
870 1130 910
1090
820
1040
760
780 1030 830 1060 880 1120 940 1155
705 1005
955
995
915 655
945 735
895 680
2100 [991] 860 615
2200 [1038]
1225 1140 1260 1175 1300 1210 1340 1255 1370 1315 1400 1375 — — — — — —
105 1180 1050
1150
1175 1085
965
1055
1145
1005
1095
830 1065 910 1100
925
1015
1040
880
1015
825
970
2400 [1133]
2300 [1085] 940 755 975 795
1175 1260 1215
1100 1170 1140 1200
1145
1095 1040
935
2500 [1179] 1015 910 1040
1 [746]
0 1 2 3 4 5 6
1405 1360 1305 1250 1195 1145 1095
RPM
Turns Open
Motor Sheave 3.4"-4.4" Pitch Diameter—Adj.
Drive Package M
Blower Sheave 6.4" Pitch Diameter
Motor H.P. [W]
NOTE: Factory sheave settings are shown in bold print.
[ ] Designates Metric Conversions
McQuay IM 970-1 31
Accessories
Accessories
Economizers
Table 12: Economizer Accessories
McQuay Model No. Single Enthalpy Economizer Fits: Airflow Direction
MXRD-TECM 3 MPS-003B through MPS-005B Convertible
RXRX-AV02 Dual Enthalpy Upgrade Kit N/A
Sensor
RXRX-AR02
Economizers: 3–5 Tons [10.6–17.6 kW]
3-5 Ton [10.6-17.6 kW] Models Single Enthalpy with Barometric Relief
Dual Enthalpy Kit 3-5 Ton [1 0.6-1 7.6 kW] Models
CO
2
N/A
3-5 Ton [1 0.6-1 7.6 kW] Models Optional CO
• Features economizer controller
• Available factory installed or field accessory
• Gear driven direct drive actuator
• Fully modulating (0-100%)
• Low leakage dampers
• Horizontal or downflow applications
• Slip-in design for easy installations
• Plug-in polarized electrical connections
Table 13: Accessory Weights
Accessory McQuay Part Number Shipping Weight Operating Weight
Economizer, Analog Controls, 3-5 ton, Vert/Horiz MXRD-TECM3 70 [32] 60 [27]
Economizer, DDC Controls, 3-5 ton, Vert/Horiz MXRD-TECM3 70 [32] 60 [27]
OA damper, 3-5 ton, Manual MXRF-FGA1 11 [5] 9 [4]
OA damper, Analog Controls, 3-5 ton, Motorized MXRF-FGB1 13 [6] 11 [5]
Power Exhaust Kit, 3 - 5 Ton 208/230 V MXRX-BGF06C 70 [32] 60 [27]
Power Exhaust Kit, 3 - 5 Ton 460 V MXRX-BGF06D 70 [32] 60 [27]
14" Roof Curb, 3-5 Ton RXKG-CBH14 92 [42] 88 [40]
Receptacle Outlet RXRX-AN01 N/A N/A
Thermostat Guard 113130101 N/A N/A
7-Day Programmable Stat 113129901 N/A N/A
Ionization Smoke Detector 113126601 N/A N/A
CO
Sensor
2
Dual Enthalpy Kit RXRX-AV02 N/A N/A
Sensor
2
• Pre-configured—no field adjustments necessary
• Standard barometric relief damper provided
• Single enthalpy with dual enthalpy upgrade kit
• CO
input sensor available (field installed)
2
• Economizer slips in complete for downflow or horizontal
duct application
• Field assembled hood ships with economizer
• Field installed power exhaust available
RXRX-AR02 N/A N/A
32 McQuay IM 970-1
Figure 36: Economizer: MPS 003B – 005B
Accessories
McQuay IM 970-1 33
Accessories
Fresh Air Dampers and Power Exhaust
Integral Power Exhaust For Economizer: 3–5 Tons [10.6–17.6 Kw] (Field Installed Only)
• For economizer controller
• Downflow or horizontal applications
• Requires separate power supply with disconnect
Figure 37: Integral Power Exhaust Economizer: MPS 003B – 005B
• Adjustable switch on economizer, factory preset to energize
power exhaust at 95% outside air position
• Polarized plug connects power exhaust relay to
economizer
Fresh Air Damper Kit for 3–5 Ton [10.6–17.6 Kw] Units
Figure 38: Damper Kit: MPS 003B – 005B
34 McQuay IM 970-1
Roofcurbs
Roofcurbs (Full Perimeter): 3–5 Tons [10.6–17.6 kW]
• One available height (14" [356 mm]) for all models.
• Quick assembly corners for easy installation
• Opening provided in bottom pan to match the “Thru the
Curb” electrical connection opening provided on the unit
base pan
Figure 39: Typical Roofcurb Installation: MPS 003B – 005B
Accessories
• 2" [51 mm] x 4" [102 mm] nailer provided
• Insulating panels provided
• Sealing gasket (28" [711 mm]) provided with roofcurb
• 18 gauge galvanized steel
McQuay IM 970-1 35
Controls and Operation
Controls and Operation
Furnace Section Controls and Ignition System
Normal Furnace Operating Sequence
This unit is equipped with an integrated direct spark ignition
control.
1 The thermostat calls for heat.
2 The control board will run a self check to verify that the
limit control and manual reset overtemperature control
are closed and that the pressure switch is open.
3 Upon closure of the pressure switch, the control board
energizes the induced draft blower for a 15 second prepurge.
4 After the 15 second prepurge, the gas valve opens and
the spark is initiated for a seven second trial for ignition.
5 Burners ignite and flame sensor proves all burners have
lit.
6 The circulating air blower is energized after 30 seconds.
7 The control board enters a normal operation loop in
which all safety controls are monitored continuously.
8 Thermostat is satisfied and opens.
9 The gas valve is de-energized and closes, shutting down
the burner flame.
10 The control board will de-energize the inducer after a
five second post purge.
11 The circulating air blower is de-energized after 90
seconds.
The integrated control is a three ignition system.
After a total of three cycles without sensing main burner
flame, the system goes into a 100% lockout mode. After one
hour, the ignition control repeats the prepurge and ignition
cycles for three tries and then goes into 100% lockout mode
again. It continues this sequence of cycles and lockout each
hour until ignition is successful or power is interrupted. During
the lockout mode, neither the ignitor or gas valve will be
energized until the system is reset by turning the thermostat to
the “OFF” position or interrupting the electrical power to the
unit for three seconds or longer. The induced draft blower and
main burner will shut off when the thermostat is satisfied.
The circulating air blower will start and run on the heating
speed if the thermostat fan switch is in the “ON” position.
The integrated furnace control is equipped with diagnostic
LED. The LED is lit continuously when there is power to the
control, with or without a call for heat. If the LED is not lit,
there is either no power to the control or there is an internal
component failure within the control, and the control should be
replaced.
If the control detects the following failures, the LED will flash
on for approximately 1/4 second, then off for 3/4 second for
designated failure detections:
1 Flash: Failed to detect flame within the three tries for
ignition.
2 Flash: Pressure switch or induced draft blower problem
detected.
3 Flash: High limit or auxiliary limit open.
4 Flash: Flame sensed and gas valve not energized or
flame sensed with no “W” signal.
5 Flash: Overtemperature switch open.
Operating Instructions
This unit is equipped with integrated furnace control. This
device lights the main burners each time the room thermostat
(closes) calls for heat. See operating instructions on the back
of the furnace/controls access panel.
DANGER
Never test for gas leaks with an open flame. It can cause an
explosion or fire resulting in property damage, personal injury
or death. Use a commercially available soap solution made
specifically for the detection of leaks to check all connections,
as specified in the Mechanical Installation section of these
instructions.
DANGER
If you do not follow these instructions exactly, a fire or
explosion may result causing property damage, personal
injury or loss of life.
36 McQuay IM 970-1
To Start The Furnace
1 STOP! Read the safety information on the Operating
Instructions label located on this unit.
2 Set the thermostat to its lowest setting.
3 Turn off all electric power to the unit.
4 This unit does not have a pilot. It is equipped with an
ignition device which automatically lights the burner. Do
NOT try to light the burner by hand.
5 Remove control door/access panel.
6 Move switch to the “OFF” position.
7 Wait five minutes to clear out any gas. Then smell for
gas, including near the floor. If you smell gas, STOP!
• Do not try to light any unit.
• Do not touch any electric switch; do not use any phone
in your building.
• Immediately call your gas supplier from a neighbor’s
phone. Follow the gas supplier’s instructions.
• If you cannot reach your gas supplier, call the fire
department.
If you don’t smell gas, go to the next step.
8 Move “OFF” position to “ON” position.
9 Replace the control door.
10 Turn on all electric power to the unit.
11 Set the thermostat to the desired setting.
12 If the unit will not operate, follow the instructions below
on how to shut down the furnace.
DANGER
Controls and Operation
DANGER
Should overheating occur or the gas supply fail to shut off,
shut off the manual gas valve to the unit before shutting off the
electrical supply. Failure to do so can result in an explosion or
fire causing property damage, severe personal injury
Burners
Burners for these units have been designed so that field
adjustment is not required. Burners are tray-mounted and
accessible for easy cleaning when required.
Manual Reset Overtemperature Control
Two manual reset overtemperature controls (one on 80,000
Btuh) are located on the burner shield. These devices sense
blockage in the heat exchanger or insufficient combustion air.
This shuts off the main burners if excessive temperatures occur
in the burner compartment.
Operation of this control indicates an abnormal condition.
Therefore, the unit should be examined by a qualified installer,
service agency , or the gas supplier before being placed back
into operation.
DANGER
Do not jumper this device! Do not reset the overtemperature
control without taking corrective action to assure that an
adequate supply of combustion air is maintained under all
conditions of operation. Failure to do so can result in carbon
monoxide poisoning or death. Replace this control only with
the identical replacement part.
The spark ignitor and ignition lead from the ignition control are
high voltage. Keep hands or tools away to prevent electrical
shock. Shut off electrical power before servicing any of the
controls. Failure to adhere to this warning can result in
personal injury or death.
The initial start-up on a new installation may require the
control system to be energized for some time until air has bled
through the system and fuel gas is available at the burners.
Pressure Switch
This furnace has a pressure switch for sensing a blocked
exhaust or a failed induced draft blower. It is normally open
and closes when the induced draft blower starts, indicating air
flow through the combustion chamber.
Limit Control
The supply air high temperature limit cut-off is set at the
To Shut Down Furnace
1 Set the thermostat to the lowest setting.
2 Turn off all electric power to the unit if service is to be
factory and cannot be adjusted. It is calibrated to prevent the
air temperature leaving the furnace from exceeding the
maximum outlet air temperature.
performed.
3 Remove control door.
4 Move switch to the “OFF” position.
5 Replace control door.
Do not jumper this device! Doing so can cause a fire or
explosion resulting in property damage, personal injury or
death.
DANGER
IMPORTANT: Replace this control only with the identical
replacement part.
McQuay IM 970-1 37
Maintenance
Maintenance
General
Advise The Customer
1 Change the air filters regularly. The heating system
operates better, more efficiently and more economically.
2 Except for the mounting platform, keep all combustible
articles three feet from the unit and exhaust system.
3 IMPORTANT: Replace all blower doors and compartment
cover after servicing the unit. Do not operate the unit without
all panels and doors securely in place.
Do not allow snow or other debris to accumulate in the
4
vicinity of the unit.
Unit Maintenance
Furnace Section
The unit’s furnace should operate for many years without
excessive scale build-up in flue passageways; however, it is
recommended that a qualified installer, service agency, or the
gas supplier annually inspect the flue passageways, the exhaust
system and the burners for continued safe operation, paying
particular attention to deterioration from corrosion or other
sources.
If during inspection the flue passageways and exhaust system
are determined to require cleaning, the following procedures
should be followed (by a qualified installer, service agency,
or gas supplier):
1 Turn off the electrical power to the unit and set the
thermostat to the lowest temperature.
DANGER
6 Remove the screws (4) connecting the burner tray to the
heat exchanger mounting panel.
7 Remove the burner tray and the manifold assembly from
the unit.
8 Remove the screws (5) connecting the induced draft
blower to the collector box and screws (18) connecting
the collector box to the heat exchanger center panel.
Remove the induced draft blower and the collector box
from the unit.
9 Remove the screws (3) connecting the divider plate to
the heat exchanger center panel.
10 Remove the turbulators from inside the heat exchangers
by inserting the blade of a screwdriver under the locking
tabs. Pop the tabs out of the expanded grooves of the heat
exchanger. Slide the turbulators out of the heat
exchangers.
11 Direct a water hose into the outlet of the heat exchanger
top. Flush the inside of each heat exchanger tube with
water. Blow out each tube with air to remove excessive
moisture.
12 Reassemble (steps 1 through 10 in reverse order). Be
careful not to strip out the screw holes used to mount
the collector box and inducer blower . Replace inducer
blower gasket and collector box gasket with factory
replacements if damaged.
DANGER
Holes in the exhaust transition or heat exchanger can cause
toxic fumes to enter the building. The exhaust transition or
heat exchanger must be replaced if they have holes or cracks
in them. Failure to do so can cause carbon monoxide
poisoning resulting in personal injury or death.
Power supply to unit must be disconnected before making
field connections. To avoid electrical shock, personal injury or
death, be sure to rigorously adhere to field wiring procedures
regarding proper lockout and tagout of components.
2 Shut off the gas supply to the unit either at the meter
or at manual valve in the supply piping.
3 Remove the furnace controls access panel and the control
The manufacturer recommends that a qualified installer,
service agency or the gas supplier visually inspect the burner
flames for the desired flame appearance at the beginning of the
heating season and approximately midway in heating season.
The manufacturer also recommends that a qualified installer,
service agency or the gas supplier clean the flame sensor with
steel wool at the beginning of the heating season.
box cover. Disconnect the gas supply piping from the gas
valve.
4 Disconnect the gas supply piping from the gas valve.
5 Disconnect the wiring to the induced draft blower motor,
gas valve, flame sensor, and flame roll-out control, and
ignitor cable. Mark all wires disconnected for proper
Power supply to unit must be disconnected before making
field connections. To avoid electrical shock, personal injury or
death, be sure to rigorously adhere to field wiring procedures
regarding proper lockout and tagout of components.
DANGER
reconnection.
38 McQuay IM 970-1
Maintenance
Lubrication
The blower motor and induced draft blower motor are prelubricated by the manufacturer and do not require further
attention.
A qualified installer, service agency or the gas supplier must
periodically clean the motors to prevent the possibility of
overheating due to an accumulation of dust and dirt on the
windings or on the motor exterior. And, as suggested
elsewhere in these instructions, the air filters should be kept
clean because dirty filters can restrict air flow and the motor
depends upon sufficient air flowing across and through it to
prevent overheating.
Cooling Section Maintenance
DANGER
Power supply to unit must be disconnected before making
field connections. To avoid electrical shock, personal injury or
death, be sure to rigorously adhere to field wiring procedures
regarding proper lockout and tagout of components.
It is recommended that at the beginning of each cooling season
a qualified installer or service agency inspect and clean the
cooling section of this unit. The following areas should be
addressed: evaporator coil. condenser coil, condenser fan
motor and venturi area.
To Inspect the Evaporator Coil
1 Remove the filter access panel and the blower/evaporator
coil access panel. Remove the filters.
DANGER
Label all wires prior to disconnection when servicing the unit.
Wiring errors can cause improper and dangerous operation
resulting in fire, electrical shock, property damage, severe
personal injury or death.
2 Shine a flashlight on the evaporator coil (both sides) and
inspect for accumulation of lint, insulation, etc.
3 If coil requires cleaning, follow the steps shown below.
Cleaning Evaporator Coil
1 The coil should be cleaned when it is dry. If the coil is
coated with dirt or lint, vacuum it with a soft brush
attachment. Be careful not to bend the coil fins.
2 If the coil is coated with oil or grease, clean it with a mild
detergent-and-water solution. Rinse the coil thoroughly
with water. IMPORTANT: Do not
use excessive water
pressure. Excessive water pressure can bend the fins and
tubing of the coil and lead to inadequate unit
performance. Be careful not to splash water excessively
into unit.
3 Inspect the drain pan and condensate drain at the same
time the evaporator coil is checked. Clean the drain pan
by flushing with water and removing any matters of
obstructions which may be present.
4 Go to next section for cleaning the condenser coil.
Cleaning Condenser Coil, Condenser Fan,
Circulation Air Blower and Venturi
1 Remove the compressor access panel. Disconnect the
wires to the condenser fan motor in the control box (see
wiring diagram). Remove the wires from the opening in
the bottom of the control box.
2 Remove the screws securing the condenser top panel and
remove the panel with condenser fan motor and grille
attached.
3 The coil should be cleaned when it is dry. If the coil is
coated with dirt or lint, vacuum it with a soft brush
attachment. Be careful not to bend the coil fins.
4 If the coil is coated with oil or grease, clean it with a mild
detergent-and-water solution. Rinse the coil thoroughly
with water. IMPORTANT: Do not
use excessive water
pressure. Excessive water pressure can bend the fins and
tubing of the coil and lead to inadequate unit
performance. Be careful not to splash water excessively
into unit.
5 The venturi should also be inspected for items of
obstruction such as collections of grass, dirt or spider
webs. Remove any that are present.
6 Inspect the circulating air blower wheel and motor for
accumulation of lint, dirt or other obstruction and clean it
as necessary. Inspect the blower motor mounts and the
blower housing for loose mounts or other damage.
Repair or replace if necessary.
Re-Assembly
1 Place the condenser top panel back on the unit and
replace all screws.
2 Run the fan motor wires through the hole in the bottom
of the control box. Reconnect fan motor wires per the
wiring diagram attached to the back of the cover.
3 Replace the filter and blower/evaporator coil access
panels.
4 Replace the control box cover and controls access panel.
5 Restore electrical power to the unit and check for proper
operation, especially the condenser fan motor.
McQuay IM 970-1 39
Maintenance
System Charge Charts
Figure 40: System Charging Chart: MPS 003B Cooling
525
500
475
450
425
400
375
350
325
300
275
250
115
105
95
85
75
65
225
55
200
175
120 125 130 135 140 145 150 155 160 165 170
40 McQuay IM 970-1
Figure 41: System Charge Chart: MPS 004B Cooling
Maintenance
McQuay IM 970-1 41
Maintenance
Figure 42: System Charge Chart: MPS 005B Cooling
42 McQuay IM 970-1
Maintenance
Blower Motor Speed Taps
After determining necessary CFM and speed tap data from the
Airflow Performance Data, follow the steps below to change
speeds (see Figure 45, page 44 for examples).
1 Remove the blower access panel.
2 Reference Figure 43 for location of the speed tap block
on the blower.
3 Remove the furnace control access panel.
4 Remove the control box cover. See Figure 44 for location
of the integrated furnace control board.
5 Reference Figure 43 and Figure 45 for the proper
location of the red and black wires on the speed tap block
and on the furnace integrated control board to obtain the
speed tap you have chosen.
6 After adjusting the wires accordingly, attach the control
box cover, furnace control access panel and the blower
access panel to the unit.
Figure 43: Speed Tap Block
Figure 44: Integrated Furnace Control
McQuay IM 970-1 43
Maintenance
Figure 45: Speed Tap Examples
44 McQuay IM 970-1
Troubleshooting
Troubleshooting
Cooling Troubleshooting Chart
DANGER
Disconnect all power to unit before servicing. Contactor may break only one side. Failure to shut off power can cause electrical
shock resulting in personal injury or death.
SYMPTOM POSSIBLE CAUSE REMEDY
Unit will not run Power off or loose electrical connection
Thermostat out of calibration-set too high Reset
Failed contactor
Blown fuses Replace fuses
Transformer defective Check wiring-replace transformer
High pressure control open (if provided)
Interconnecting low voltage wiring damaged Replace thermostat wiring
Condenser fan runs, compressor doesn’t Loose connection
Compressor stuck, grounded or open motor
winding, open internal overload.
Low voltage condition
Low voltage condition Add start kit components
Insufficient cooling Improperly sized unit Recalculate load
Improper airflow
Incorrect refrigerant charge
Air, non-condensable or moisture in system
Incorrect voltage
Compressor short cycles Incorrect voltage
Defective overload protector Replace check for correct voltage
Refrigerant undercharge Add refrigerant
Registers sweat Low evaporator airflow
High head-low vapor pressures
High head-high or normal vapor pressure
Cooling mode
Low vapor - cool compressor iced
evaporator coil
Low vapor cool evaporator coil Low evaporator airflow
High vapor pressure Excessive load Recheck load calculation
Fluctuating head & vapor Air or non-condensate in system Recover refrigerant, evacuate & recharge
Gurgle or pulsing noise at expansion
device or liquid line
Restriction in liquid line, expansion device or filter
drier
Flow check piston size too small Change to correct size piston
Incorrect capillary tubes Change coil assembly
Dirty condenser coil Clean coil
Refrigerant overcharge Correct system charge
Condenser fan not running Repair or replace
Air or non-condensable in system Recover refrigerant, evacuate & recharge
Defective compressor valves Replace compressor
Incorrect capillary tubes Replace coil assembly
Operating below 65°F outdoors Add low ambient kit
Moisture in system
Defective compressor Replace
Air or non-condensable in system Recover refrigerant, evacuate & recharge
Check for correct voltage at compressor
contactor in control box
Check for 24 volts at contactor coil replace if
contacts are open
Reset-also see high head pressure remedy-The
high pressure control opens at 450 PSIG
Check for correct voltage at compressor check
& tighten all connections
Wait at least 2 hours for overload to reset. If still
open, replace the compressor.
At compressor terminals, voltage must be within
10% of rating plate volts when unit is operating
Check should be approximately 400 CFM per
ton.
Charge per procedure attached to unit service
panel
Recover refrigerant, evacuate & recharge, add
filter drier
At compressor terminals, voltage must be within
10% of rating plate volts when unit is operating.
At compressor terminals, voltage must be ±10%
of nameplate marking when unit is operating.
Increase speed of blower or reduce restriction
replace air filter
Remove or replace defective component
Increase speed of blower or reduce restriction
replace air filter
Recover refrigerant evacuate & recharge add
filter drier
McQuay IM 970-1 45
Troubleshooting
Furnace Troubleshooting Guide
Figure 46: Furnace Troubleshooting Guide (Combination Heating and Cooling Units with Direct Spark Ignition)
WARNING
!
▲
DISCONNECT POWER BEFORE
SERVICING.
SERVICE MUST BE BY A TRAINED,
QUALIFIED SERVICE TECHNICIAN.
REPLACE INTEGRATED
CONTROL BOARD (IFC)
NO
YES
REPLACE IGNITOR/
CABLE ASSEMBLY
START
SET THERMOSTAT TO
CALL FOR HEAT
SET FAN SWITCH TO AUTO
YES
INDUCED DRAFT BLOWER
MOTOR STARTS
YES
30 SECOND PREPURGE
NO
HAZARDOUS VOLTAGE
LINE VOLTAGE
CONNECTIONS
• CHECK LINE VOLTAGE TO IFC
• CHECK LOW VOLTAGE TRANSFORMER
• CHECK WIRING
• CHECK FOR 208-230 VAC TO IDM MOTOR
REPLACE INDUCED
DRAFT BLOWER
YES
IGNITOR SPARKS
YES
MAIN BURNER LIGHTS
YES
NO
NO
• CHECK IGNITOR CABLE
• CHECK SPARK IGNITOR POSITION AND CONDITION
• IS EACH NEGATIVE PRESSURE SWITCH CLOSED?
• CHECK FOR OPEN ROLL-OUT CONTROLS
• CHECK FOR OPEN LIMIT
• CHECK IGNITION CONTROL CHASSIS GROUND WIRE
• CHECK WIRING
NO
REPLACE IGNITION
CONTROL
NOTE: THE SYSTEM WILL ATTEMPT TO LIGHT 4 TIMES WITH A 60 SECOND INTER-
PURGE BETWEEN TRIES. IF AFTER THE THIRD TIME THE BURNERS
DO NOT LIGHT, THE SYSTEM WILL LOCK OUT. IF THE UNIT IS EQUIPPED WITH A
UNITED TECH. THE SYSTEM WILL ATTEMPT TO LIGHT 4 TIMES EACH HOUR
UNTIL THE BURNERS LIGHT OR THE THERMOSTAT IS RESET OR POWER IS
REMOVED FOR 3 SECONDS OR GREATER.
• CHECK INLET GAS PRESSURE
• CHECK 24 VOLTS TO GAS VALVE
• CHECK FOR GAS FLOW TO AND FROM VALVE
• CHECK BURNER CARRYOVER
YES
NO
YES
YES
NO
• CHECK NEGATIVE PRESSURE
SWITCH SENSING TUBE
• CHECK FOR EXHAUST
BLOCKAGE
REPLACE NEGATIVE
PRESSURE SWITCH
CHECK FOR EXHAUST,
EXCHANGER BLOCKAGE
AND RESET CONTROL
REPLACE LIMIT
IF UNIT IS COLD
REPLACE INTEGRATED
CONTROL BOARD (IFC)
NO
INTAKE OR HEAT
IF WIRING IS OK
YES
REPLACE VALVE
46 McQuay IM 970-1
MAIN BURNER FLAME SUSTAINED
YES
NO
NOTE: IF THE SYSTEM GOES INTO LOCKOUT, WAIT
30 SECONDS AND RESET THE SYSTEM.
• CHECK FLAME SENSOR POSITION AND CONDITION
• CLEAN FLAME SENSOR WITH STEEL WOOL
• CHECK FLAME SENSOR WIRES AND CONNECTIONS
NO
REPLACE IGNITION
CONTROL
Troubleshooting
YES
REPLACE SENSOR
INDOOR BLOWER MOTOR STARTS
AFTER 45 SECONDS
YES
SYSTEM RUNS UNTIL
CALL FOR HEAT ENDS
YES
FURNACE STARTS ON LOW OR HIGH
FIRE. FURNACE SWITCHES TO LOW
FIRE AFTER 120 SECONDS WARMUP
IF THERMOSTAT IS CALLING FOR W1.
FURNACE WILL SWITCH TO HIGH
FIRE IF LOW FIRE DOES NOT SATISFY
THERMOSTAT DEMAND FOR HEAT
LOAD.
YES
TURN THERMOSTAT OFF
VALVE SHUTS OFF
FLAME SHUTS OFF
YES
NO
NO
NO
• CHECK FOR 208-230 VAC ACROSS BLOWER
MOTOR TERMINALS ON CONTROL BOARD
• CHECK FOR LINE VOLTAGE AT LOAD SIDE OF
BLOWER CONTACT.
YES
REPLACE BLOWER
MOTOR
• CHECK FOR OPEN LIMIT
• CHECK FOR OPEN ROLL-OUT CONTROL
• CHECK FOR PROPER THERMOSTAT OPERATION
• REMOVE VALVE LEAD AT GAS VALVE
IF VALVE CLOSES, RECHECK THE THERMOSTAT
AND WIRING. IF OK,THEN REPLACE VALVE
NO
YES
YES
REPLACE INTEGRATED
CONTROL BOARD (IFC)
• CHECK FOR DIRTY FILTERS
• CHECK FOR RESTRICTED
AIR-FLOW
CHECK FOR EXHAUST,
INTAKE OR HEAT
EXCHANGER BLOCKAGE
CLEAR BLOCKAGE AND
RESET CONTROL
INDUCED DRAFT MOTOR STOPS
AFTER 5 SECOND POSTPURGE
YES
INDOOR BLOWER MOTOR STOPS
AFTER 90 SECONDS
YES
TROUBLESHOOTING ENDS
REPEAT PROCEDURE UNTIL TROUBLE FREE
OPERATION IS OBTAINED.
McQuay IM 970-1 47
Warranty
Warranty
Replacement Parts
To find your local McQuay Certified Parts Distribu tor, go to
www.mcquay.com
and select Parts Locator.
48 McQuay IM 970-1
Warranty
McQuay IM 970-1 49
McQuay Training and Development
Now that you have made an investment in modern, efficien t McQuay equipment, its care should be a high priority.
For training information on all McQuay HVAC products, please visit us at www.mcquay.com and click on training,
or call 540-248-9646 and ask for the Training Department.
Warranty
All McQuay equipment is sold pursuant to its standard terms and conditions of sale, including Limited Product
Warranty. Consult your local McQuay Representative for warranty details. Refer to Form 933-43285Y. To find your
local McQuay Representative, go to www.mcquay.com.
This document contains the most current product info rm a tio n as of this pr int ing . Fo r th e mo st up - to- d ate pro d uc t
information, please go to www.mcquay.com.
© 2010 McQuay International • www.mcquay.com • 800-432-1342
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