Daikin DCG Series Manual

Installation and Maintenance Manual IM 1213
Group: Applied Air Systems
Part Number: IM 1213
Date: January 2014
Light Commercial Packaged Gas Units
DCG Series
15–20 Tons

WARNING
ATTENTION INSTALLING PERSONNEL:
Prior to installation, thoroughly familiarize yourself with this
Installation Manual. Observe all safety warnings. During
installation or repair, caution is to be observed. It is your
responsibility to install the product safely and to educate the
customer on its safe use.
RECOGNIZE THIS SYMBOL AS A SAFETY PRECAUTION.
These installation instructions cover the outdoor installation of single package heating and cooling units. See the Specication
Sheet applicable to your model for information regarding accessories.
NOTE: Please contact your distributor or our website for the applicable Specication Sheet referred to in this manual.
This Forced Air Central Unit Design Complies With Requirements Embodied In The American National Standard / National
Standard of Canada Shown Below.
ANSI Z21.47 • CSA-2.3 Central Furnaces
Our continuing commitment to quality products may mean a change in specications without notice.
©2013 Daikin Company, L.P.
5151 San Felipe St., Suite 500, Houston, TX 77056
www.daikincomfort.com

Index
Replacement Parts ...........................2
Safety Instructions ............................2
General Information ...........................3
Unit Location.................................4
Clearances ..................................6
Roof Curb Post-Installation Checks ..............6
Roof Top Duct Connections ....................6
Rigging Details ...............................6
Electrical Wiring ..............................8
Gas Supply Piping ............................9
Propane Gas Installations .....................11
Circulating Air and Filters .....................12
Venting.....................................12
Condensate Drain Connection .................12
Startup, Adjustments, and Checks ..............13
Air ow Adjustments .........................14
Motor Sheave Adjustments ....................15
Gas System Check ...........................15
Normal Sequence Of Operation - Heating ........18
Normal Sequence Of Operation - Cooling ........19
Maintenance ................................20
Troubleshooting .............................
22
Appendix A Blower Performance Data...........24
Belt Drive - Standard .........................24
Appendix B Electrical Data ....................25
Appendix C Unit Dimensions ..................26
Appendix D Wiring Diagrams ..................27

2
REPLACEMENTPARTS
ORDERING PARTS
When reporting shortages or damages, or ordering repair
parts, give the complete unit model and serial numbers as
stamped on the unit’s nameplate.
Replacement parts for this appliance are available through
your contractor or local distributor. For the location of your
nearest distributor, consult the white business pages, the
yellow page section of the local telephone book or contact:
CONSUMER AFFAIRS
DAIKIN NORTH AMERICA LLC
7401 SECURITY WAY
HOUSTON, TEXAS 77040
855-770-5678
SAFETYINSTRUCTIONS
TOTHE INSTALLER
Before installing this unit, please read this manual to
familiarize yourself on the specific items which must be
adhered to, including maximum external static pressure to
unit, air temperature rise, minimum or maximum CFM and
motor speed connections.
Keep this literature in a safe place for future reference.
I F THE INFORMATION IN THESE INSTRUCTIONS IS NOT FOLLOWED
EXACTLY , A FIRE OR EXPLOSION MAY RESULT CAUSING PROPERTY
DAMAGE
, PERSONAL INJURY OR LOSS OF LIFE .
D O NOT STORE OR USE GASOLINE OR OTHER FLAMMABLE VAPORS AND
LIQUIDS IN THE VICINITY OF THIS OR ANY OTHER APPLIANCE .
D
O NOT TRY TO LIGHT ANY APPLIANCE .
D
O NOT TOUCH ANY ELECTRICAL SWITCH ; DO NOT USE ANY PHONE
IN YOUR BUILDING .
I
MMEDIATELY CALL YOUR GAS SUPPLIER FROM A NEIGHBOR ’ S
PHONE . F OLLOW THE GAS SUPPLIER ’ S INSTRUCTIONS .
I
F YOU CANNOT REACH YOUR GAS SUPPLIER , CALL THE FIRE
DEPARTMENT .
I
NSTALLATION AND SERVICE MUST BE PERFORMED BY A QUALIFIED
INSTALLER , SERVICE AGENCY OR THE GAS SUPPLIER .
WHAT TO DO IF YOU SMELL GAS:




WARNING
S HOULD OVERHEATING OCCUR OR THE GAS SUPPLY FAIL TO SHUT OFF ,
TURN OFF THE MANUAL GAS SHUTOFF VALVE EXTERNAL TO THE
FURNACE
BEFORE TURNING OFF THE ELECTRICAL SUPPLY .
WARNING
S HEET METAL PARTS , SCREWS , CLIPS AND SIMILAR ITEMS INHERENTLY
HAVE SHARP EDGES , AND IT IS NECESSARY THAT THE INSTALLER AND
SERVICE PERSONNEL EXERCISE CAUTION .
CAUTION
D O NOT CONNECT TO OR USE ANY DEVICE THAT IS NOT DESIGN
CERTIFIED BY D AIKIN FOR USE WITH THIS UNIT . S ERIOUS PROPERTY
DAMAGE , PERSONAL INJURY , REDUCED UNIT PERFORMANCE AND / OR
HAZARDOUS CONDITIONS MAY RESULT FROM THE USE OF SUCH NON -
APPROVED DEVICES .
WARNING
T HIS PRODUCT CONTAINS OR PRODUCES A CHEMICAL OR CHEMICALS
WHICH MAY CAUSE SERIOUS ILLNESS OR DEATH AND WHICH ARE
KNOWN
TO THE S TATE OF C ALIFORNIA TO CAUSE CANCER , BIRTH
DEFECTS OR OTHER REPRODUCTIVE HARM .
WARNING
T O AVOID PROPERTY DAMAGE , PERSONAL INJURY OR DEATH , DO NOT
USE THIS UNIT IF ANY PART HAS BEEN UNDER WATER . I MMEDIATELY
CALL A QUALIFIED SERVICE TECHNICIAN TO INSPECT THE FURNACE AND
TO
REPLACE ANY PART OF THE CONTROL SYSTEM AND ANY GAS
CONTROL
HAVING BEEN UNDER WATER .
WARNING
T HIS UNIT MUST NOT BE USED AS A “ CONSTRUCTION HEATER ” DURING
THE FINISHING PHASES OF CONSTRUCTION ON A NEW STRUCTURE . T HIS
TYPE OF USE MAY RESULT IN PREMATURE FAILURE OF THE UNIT DUE TO
EXTREMELY
LOW RETURN AIR TEMPERATURES AND EXPOSURE TO
CORROSIVE
OR VERY DIRTY ATMOSPHERES .
WARNING
HIGH VOLTAGE !
D ISCONNECT ALL POWER BEFORE SERVICING OR
INSTALLING THIS UNIT . M ULTIPLE POWER SOURCES MAY
BE PRESENT . F AILURE TO DO SO MAY CAUSE PROPERTY
DAMAGE , PERSONAL INJURY OR DEATH .
WARNING
T O PREVENT THE RISK OF PROPERTY DAMAGE , PERSONAL INJURY OR
DEATH , DO NOT STORE COMBUSTIBLE MATERIALS OR USE GASOLINE OR
OTHER FLAMMABLE LIQUIDS OR VAPORS IN THE VICINITY OF THIS
APPLIANCE
.
WARNING
HIGH VOLTAGE!
I NSTALLATION AND REPAIR OF THIS UNIT SHOULD BE
PERFORMED ONLY BY INDIVIDUALS MEETING ( AT A
MINIMUM ) THE REQUIREMENTS OF AN “E NTRY L EVEL
T
ECHNICIAN ” AS SPECIFIED BY THE A IR C ONDITIONING ,
H
EATING , AND R EFRIGERATION I NSTITUTE (AHRI).
A
TTEMPTING TO INSTALL OR REPAIR THIS UNIT WITHOUT
SUCH BACKGROUND MAY RESULT IN PRODUCT DAMAGE ,
PERSONAL INJURY OR DEATH .
WARNING

3
GENERALINFORMATION
T O PREVENT PROPERTY DAMAGE , PERSONAL INJURY OR DEATH DUE TO
FIRE , EXPLOSIONS , SMOKE , SOOT , CONDENSATION , ELECTRIC SHOCK OR
CARBON MONOXIDE , THIS UNIT MUST BE PROPERLY INSTALLED ,
REPAIRED , OPERATED AND MAINTAINED .
WARNING
Thisunit isapprovedforoutdoor installationONLY. Ratedperfor-
manceisachievedafter72hoursofoperation.Ratedperformance
is delivered at the specified airflow. See outdoor unit specifica-
tion sheet for split system models or product specification sheet
for packaged and light commercial models. Specification sheets
can be found at www.daikincomfort.com for Daikin brand prod-
ucts. Within the website, please select the residential or com-
mercialproductsmenu andthenselectthesubmenuforthe type
ofproducttobeinstalled,suchasairconditionersorheatpumps,
to access a list of product pages that each contain links to that
model’s specification sheet.
To assure that your unit operates safely and efficiently, it must be
installed, operated, and maintained in accordance with these in-
stallation and operating instructions, all local building codes and
ordinances, or in their absence, with the latest edition of the Na-
tional Fuel Gas Code NFPA54/ANSI Z223.1 and National Standard
of Canada CAN/CSA B149 Installation Codes.
EPA REGULATIONS
IMPORTANT:THE UNITED STATES ENVIRONMENTAL PROTECTION AGENCY (EPA)
HAS ISSUED VARIOUS REGULATIONS REGARDING THE INTRODUCTION AND DISPOSAL
OF REFRIGERANTS IN THIS UNIT. FAILURE TO FOLLOW THESE REGULATIONS MAY
HARM THE ENVIRONMENT AND CAN LEAD TO THE IMPOSITION OF SUBSTANTIAL
FINES. BECAUSE REGULATIONS MAY VARY DUE TO PASSAGE OF NEW LAWS, WE
SUGGEST ACERTIFIED TECHNICIAN PERFORM ANY WORK DONE ON THIS UNIT.
SHOULD YOU HAVE ANY QUESTIONS PLEASE CONTACT THE LOCAL OFFICE OF THE
EPA.
NATIONAL CODES
This product is designed and manufactured to permit installation
in accordance with National Codes. It is theinstaller’s responsibil-
ity to install the product in accordance with National Codes and/
or prevailing local codes and regulations.
The heating and cooling capacities of the unit should be greater
than or equal to the design heating and cooling loads of the area
to be conditioned. The loads should be calculated by an approved
method or in accordance with ASHRAE Guide or Manual J - Load
Calculations published by the Air Conditioning Contractors of
America.
Obtain from:
American National Standards Institute
1430 Broadway
New York, NY 10018
System design and installation should also, where applicable, fol-
lowinformationpresentedinacceptedindustryguidessuchasthe
ASHRAE Handbooks. The manufacturer assumes no responsibility
forequipment installedinviolationof anycode or regulation.The
mechanical installation of the packaged roof top units consists of
making final connections between the unit and building services;
supply and return duct connections; and drain connections (if re-
quired). The internal systems of the unit are completely factory-
installed and tested prior to shipment.
Units are generally installed on a steel roof mounting curb assem-
bly which has been shipped to the job site for installation on the
roof structure prior to the arrival of the unit. The model number
shownontheunit’sidentificationplateidentifiesthevariouscom-
ponents of the unit such as refrigeration tonnage, heating input
and voltage.
Carefully inspect the unit for damage including damage to the
cabinetry. Anyboltsorscrews whichmayhaveloosenedintransit
mustbere-tightened. Intheeventofdamage,thereceivershould:
1. Make notation on delivery receipt of any visible damage
to shipment or container.
2. Notify carrier promptly and request an inspection.
3. Incaseofconcealeddamage,carrier shouldbenotifiedas
soon as possible-preferably within 5 days.
4. File the claim with the following supporting documents:
a. Original Bill of Lading, certifiedcopy, or indemnity bond.
b. Original paid freight bill or indemnity in lieu thereof.
c. Original invoice or certified copy thereof, showing trade
and other discounts or reductions.

4
d. Copy of the inspection report issued by carrier
representative at the time damage is reported to the
carrier. The carrier is responsible for making prompt
inspection of damage and for a thorough investigation
of each claim. The distributor or manufacturer will not
accept claims from dealers for transportation damage.
NOTE: When inspecting the unit for transportation damage, re-
move allpackagingmaterials.Recycleordispose ofthepackaging
material according to local codes.
PRE-INSTALLATION CHECKS
Carefullyreadall instructionsfor the installationprior to installing
unit.Ensureeachstepor procedureisunderstoodand anyspecial
considerations are taken into account before starting installation.
Assemblealltools,hardwareandsuppliesneededtocompletethe
installation. Some items may need to be purchased locally.
UNITLOCATION
T O PREVENT POSSIBLE EQUIPMENT DAMAGE , PROPERTY DAMAGE ,
PERSONAL INJURY OR DEATH , THE FOLLOWING BULLET POINTS MUST BE
OBSERVED WHEN INSTALLING THE UNIT .
WARNING
IMPORTANT NOTE: Remove wood shipping rails prior to installa-
tion of the unit. See important note under Roof Curb Installation
Only.
ALL INSTALLATIONS:
IMPORTANT NOTE: Unit should be energized 24 hours prior to
compressor start up to ensure crankcase heater has suffi-
ciently warmed the compressors. Compressor damage may
occur if this step is not followed.
NOTE: This appliance is a dedicated downflow design.
Proper installation of the unit ensures trouble-free operation. Im-
proper installation can result in problems ranging from noisy
operation to property or equipment damages, dangerous condi-
tions that could result in injury or personal property damage and
could void the warranty. Give this booklet to the user and explain
it’sprovisions. The user should retain these instructionsforfuture
reference.
•For proper flame pattern within the heat exchanger and
proper condensate drainage, the unit must be mounted
level.
•Theflueoutletmustbeatleast12inchesfromanyopening
through which flue gases could enter a building, and at
least three feet above any forced air inlet located within
ten feet. The economizer/manual fresh air intake/
motorized fresh air intake and combustion air inlet
mounted on the unit are not affected by this restriction.
•To avoid possible corrosion of the heat exchanger, do not
locate the unit in an area where the outdoor air (i.e.
combustion air for the unit) will be frequently
contaminated by compounds containing chlorine or
fluorine. Common sources of such compounds include
swimming pool chemicals and chlorine bleaches, paint
stripper,adhesives,paints,varnishes,sealers,waxes(which
are not yet dried) and solvents used during construction
and remodeling. Various commercial and industrial
processes may also be sources of chlorine/fluorine
compounds.
•Toavoidpossibleillnessordeathofthebuildingoccupants,
do NOT locate outside air intake device (economizer,
manual fresh air intake, motorized fresh air intake) too
close to an exhaust outlet, gas vent termination, or
plumbing vent outlet. For specific distances required,
consult local codes.
•Allow minimum clearances from the enclosure for fire
protection,properoperation,andservice access(seeunit
clearances). These clearances must be permanently
maintained.
•The combustion air inlet and flue outlet on the unit must
neverbeobstructed.Ifused,donotallowtheeconomizer/
manual fresh air damper/ motorized fresh air damper to
become blocked by snow or debris. In some climates or
locations,it maybe necessary to elevatethe unittoavoid
these problems.
•When the unit is heating, the temperature of the return
air entering the unit must be between 50° F and 100° F.
GROUND LEVEL INSTALLATIONS ONLY:
•When the unit is installed on the ground adjacent to the
building,alevelconcrete(orequal)baseisrecommended.
Prepare a base that is 3” larger than the package unit
footprint and a minimum of 3” thick.
•Thebaseshould also be locatedwhere no runoff of water
from higher ground can collect in the unit.
ROOF TOP INSTALLATIONS ONLY:
•Toavoidpossible property damageor personalinjury, the
roof must have sufficient structural strength to carry the
weight of the unit(s) and snow or water loads as required
bylocalcodes. Consultastructuralengineertodetermine
the weight capabilities of the roof.
•The unit may be installed directly on wood floors or on
Class A, Class B, or Class C roof covering material.
•To avoid possible personal injury, a safe, flat surface for
service personnel should be provided.
•As indicated on the unit data plate, a minimum clearance
of 36” to any combustible material is required on the
furnaceaccesssideofthe unit. All combustible materials
must be kept out of this area.
•This 36” clearance must also be maintained to insure
propercombustion airand flue gasflow. The combustion
airintake andfurnace fluedischargemustnot be blocked
for any reason, including blockage by snow.
•Adequate clearances from the furnace flue discharge to
anyadjacentpublicwalkways,adjacentbuildings,building
openings or openable windows must be maintained in
accordancewiththelatesteditionoftheNationalFuelGas
Code (ANSI Z223.1)

5
•Minimum horizontal clearance of 48” from the furnace
fluedischargetoanyelectricmeters,gasmeters,regulators
and relief equipment is required.
UNIT PRECAUTIONS
• Do not stand or walk on the unit.
• Except for holes in the wiring entrances (see Figure
below), do not drill holes anywhere in panels or in the
base frame of the unit. Unit access panels provide
structural support.
• Do not remove any access panels until unit has been
installed on roof curb or field suppliedstructure.
• Donotrollunitacrossfinishedroofwithoutpriorapproval
of owner or architect.
• Do not skid or slide on any surface as this may damage
unitbase. Theunitmustbestoredonaflat,levelsurface.
Protect the condenser coil because it is easily damaged.
ROOF CURB INSTALLATIONS ONLY:
Before installing this unit...
IMPORTANT NOTE: This unit has been equipped with a shipping
braceunderthecompressorsectionthatMUST BE REMOVED be-
fore installing the unit on a roof curb.
Please follow the instructions below to remove brace.
W HEN UNIT IS SUSPENDED , BOARDS AND SHIPPING BRACE WILL DROP WHEN
SCREWS ARE REMOVED . T O PREVENT PERSONAL INJURY , STAND CLEAR.
R
EMOVE FORK HOLE BRACKETS , BOARDS AND SHIPPING BRACE FROM BOTTOM
OF
UNIT BEFORE PLACING UNIT ONTO CURB .
CAUTION
1. Removewoodenstrutsandshippingbraceperinstallation
instructions. The struts are located in the fork holes and
areusedtoprotecttheunitfromdamagewhileliftingwith
forks. Theshippingbrace islocated under theunit(under
compressor). Alsoremovetheforkholebracketsasshown
in the following figure.
2. Locate and remove the end brackets as shown in the
following figure.
LIFT OVER APPROXIMATE
CENTER OF UNIT
SPREADER BARS
MUST BE USED WITH
LIFTING STRAPS THAT
ARE LESS THAN 16
FEET LONG
REMOVE 2 BRACKETS
ON EACH END TO
REMOVE
WOODEN STRUTS
REMOVE 2 BRACKETS
ON EACH END TO
REMOVE
SHIPPING BRACE
3. Lift unit per the “Rigging Details” section of this manual,
observing all warnings and cautions. When unit is lifted,
boards and shipping brace will drop if screws have been
removed. To avoid injury, STAND CLEAR.
4. Dispose of the boards and brace appropriately.
Curbinstallationsmustcomplywithlocalcodesandshouldbedone
inaccordancewiththeestablishedguidelinesoftheNationalRoof-
ing Contractors Association.
Proper unit installation requires that the roof curb be firmly and
permanently attached to the roof structure. Check for adequate
fastening method prior to setting the unit on the curb.
Full perimeter roof curbs are available from the factory and are
shipped unassembled. Field assembly, squaring, leveling and
mounting on the roof structure are the responsibility of the in-
stalling contractor. All required hardware necessary for the as-
sembly of the sheet metal curb is included in the curb accessory.
T O PREVENT POSSIBLE EQUIPMENT DAMAGE , PROPERTY DAMAGE ,
PERSONAL INJURY OR DEATH , THE FOLLOWING BULLET POINTS MUST BE
OBSERVED WHEN INSTALLING THE UNIT .
WARNING

6
•Sufficient structural support must be determined prior to
locating and mounting the curb and package unit.
•Ductwork must be constructed using industry guidelines.
The duct work must be placed into the roof curb before
mounting the package unit. Our full perimeter curbs
includeduct connectionframes to be assembledwiththe
curb. Cantilevered type curbs are not available from the
factory.
•Curb insulation, cant strips, flashing and general roofing
material are furnished by the contractor.
The curbs must be supported on parallel sides by roof members.
The roof members must not penetrate supply and return duct
opening areas as damage to the unit might occur.
NOTE:Theunitandcurbaccessoriesaredesignedtoallowvertical
ductinstallationbeforeunitplacement. Ductinstallationafterunit
placement is not recommended.
A LL CURBS LOOK SIMILAR . T O AVOID INCORRECT CURB POSITIONING ,
CHECK JOB PLANS CAREFULLY AND VERIFY MARKINGS ON CURB
ASSEMBLY . I NSTRUCTIONS MAY VARY IN CURB STYLES AND SUPERCEDE
INFORMATION SHOWN .
CAUTION
See the manual shipped with the roof curb for assembly and in-
stallation instructions.
CLEARANCES
48”
Min.
48”
Min.
36”; minimum
roof overhang
48”
UNIT CLEARANCES
Adequateclearancearoundtheunitshouldbekeptforsafety,ser-
vice, maintenance, and proper unit operation. A total clearance
of75”aroundthisunitisrecommendedtofacilitatepossibleblower
assembly, shaft, wheel replacement, coil, heat exchanger, electric
heat and gas furnace removal. This unit must not be installed be-
neath any obstruction. This unit should be installed remote from
all building exhausts to inhibit ingestion of exhaust air into the
unit’s fresh air intake.
NOTE: If the 48” minimum is used on the control panel side of a
DCG unit, a flue extension (MF# 220-GX-03) needs be to installed
to prevent flue gas recirculation.
.
INSULATED
PANELS
ROOF CURB INSTALLATION
ROOFCURBPOST-INSTALLATIONCHECKS
Afterinstallation,checkthetopofthecurb,ductconnectionframe
and duct flanges to make sure gasket has been applied properly.
Gasket should be firmly applied to the top of the curb perimeter,
duct flanges and any exposed duct connection frame. If gasket is
loose, re-apply using strong weather resistant adhesive.
PROTRUSION
Inspect curb to ensure that none of the utility services (electric)
routed through the curb protrude above the curb.
I F PROTRUSIONS EXIST , DO NOT ATTEMPT TO SET UNIT ON CURB .
I
NFORMATION SHOWN .
CAUTION
ROOFTOPDUCTCONNECTIONS
Install all duct connections on the unit before placing the unit on
rooftop.
RIGGINGDETAILS
T O PREVENT PROPERTY DAMAGE , THE UNIT SHOULD REMAIN IN AN
UPRIGHT POSITION DURING ALL RIGGING AND MOVING OPERATIONS .
T
O FACILITATE LIFTING AND MOVING WHEN A CRANE IS USED , PLACE
THE UNIT IN AN ADEQUATE CABLE SLING .
WARNING

7
D O NOT LIFT UNITS TWO AT A TIME . P ROVISIONS FOR FORKS HAVE BEEN
INCLUDED IN THE UNIT BASE FRAME . M INIMUM FORK LENGTH IS 72” TO
PREVENT DAMAGE TO THE UNIT .
CAUTION
Provisionsforforkshavebeenincludedintheunitbaseframe. No
other fork locations are approved.
T O PREVENT POSSIBLE EQUIPMENT DAMAGE , PROPERTY DAMAGE ,
PERSONAL INJURY OR DEATH , THE FOLLOWING BULLET POINTS MUST BE
OBSERVED WHEN INSTALLING THE UNIT .
WARNING
• Unit must be lifted by the four lifting holes located at the
base frame corners.
• Liftingcablesshouldbeattachedtotheunitwithshackles.
• The distance between the crane hook and the top of the
unit must not be less than 60”.
• Two spreader bars must span over the unit to prevent
damage to the cabinet by the lift cables. Spreader bars
must be of sufficient length so that cables do not come in
contact with the unit during transport. Remove wood
struts mounted beneath unit base frame before setting
unit on roof curb. These struts are intended to protect
unit base frame from fork lift damage. Removal is
accomplishedby extractingthe sheet metalretainersand
pulling the struts through the base of the unit. Refer to
rigging label on the unit.
Important: If using bottom discharge with roof curb, ductwork
shouldbeattachedtothecurbpriortoinstallingtheunit.Ductwork
dimensions are shown in Roof Curb Installation Instructions.
Refer to the Roof Curb Installation Instructions for proper curb
installation. Curbing must be installed in compliance with the Na-
tional Roofing Contractors Association Manual.
Lower unit carefully onto roof mounting curb. While rigging unit,
centerofgravitywillcausecondenserendtobelowerthansupply
air end.
W HEN UNIT IS SUSPENDED , BOARDS AND SHIPPING BRACE WILL DROP WHEN
SCREWS ARE REMOVED . T O PREVENT PERSONAL INJURY , STAND CLEAR.
R
EMOVE FORK HOLE BRACKETS , BOARDS AND SHIPPING BRACE FROM BOTTOM
OF
UNIT BEFORE PLACING UNIT ONTO CURB .
CAUTION
To assist in determining rigging requirements, unit weights are
shown as follows:
COMPRESSOR 1
COMPRESSOR 2
CG
EVAPORATORCOILS
A
B
C
XD
Y
CORNER & CENTER OF GRAVITY LOCATIONS
Corner Weight- A 582 645
Corner Weight- B 475 527
Corner Weight- C 565 589
Corner Weight- D 461 481
UnitShippingWeight 2198 2357
UnitOperatingWeight 2083 2242
X (Inches) 65" 63"
Y(Inches) 40" 40"
DATA
DCG Weights
(lbs)
15 Tons 20 Tons
NOTE: Theseweights are withoutaccessories installed.
T O PREVENT SEVERE DAMAGE TO THE BOTTOM OF THE UNIT , DO NOT
FORK LIFT UNIT AFTER WOOD STRUTS HAVE BEEN REMOVED .
CAUTION
Bring condenser end of unit into alignment with the curb. With
condenserend of the unit restingon curb member and using curb
as a fulcrum, lower opposite end of the unit until entire unit is
seated on the curb. When a rectangular cantilever curb is used,
care should be taken to center the unit. Check for proper align-
ment and orientation of supply and return openings with duct.

8
RIGGING REMOVAL
T O PREVENT DAMAGE TO THE UNIT , DO NOT ALLOW CRANE HOOKS AND
SPREADER BARS TO REST ON THE ROOF OF THE UNIT .
CAUTION
Removespreaderbars,liftingcablesandotherriggingequipment.
ELECTRICALWIRING
HIGH VOLTAGE !
D ISCONNECT ALL POWER BEFORE SERVICING OR
INSTALLING THIS UNIT . M ULTIPLE POWER SOURCES MAY
BE PRESENT . F AILURE TO DO SO MAY CAUSE PROPERTY
DAMAGE , PERSONAL INJURY OR DEATH .
WARNING
HIGH VOLTAGE !
T O AVOID PERSONAL INJURY OR DEATH DUE TO ELECTRICAL
SHOCK , DO NOT TAMPER WITH FACTORY WIRING . T HE
INTERNAL POWER AND CONTROL WIRING OF THESE UNITS
ARE FACTORY - INSTALLED AND HAVE BEEN THOROUGHLY
TESTED PRIOR TO SHIPMENT . C ONTACT YOUR LOCAL
REPRESENTATIVE IF ASSISTANCE IS REQUIRED .
WARNING
T O PREVENT DAMAGE TO THE WIRING , PROTECT WIRING FROM SHARP
EDGES . F OLLOW NATIONAL ELECTRICAL CODE AND ALL LOCAL CODES
AND ORDINANCES . D O NOT ROUTE WIRES THROUGH REMOVABLE
ACCESS PANELS .
CAUTION
C ONDUIT AND FITTINGS MUST BE WEATHER - TIGHT TO PREVENT WATER
ENTRY INTO THE BUILDING .
CAUTION
For unit protection, use a fuse or HACR circuit breaker that is in
excess of the circuit ampacity, but less than or equal to the maxi-
mum overcurrent protection device. DO NOT EXCEED THE MAXI-
MUM OVERCURRENT DEVICE SIZE SHOWN ON UNIT DATA PLATE.
All line voltage connections must be made through weatherproof
fittings. All exterior power supply and ground wiring must be in
approved weatherproof conduit.
The main power supply wiring to the unit and low voltage wiring
to accessory controls must be done in accordance with these in-
structions,thelatesteditionoftheNationalElectricalCode(ANSI/
NFPA 70), and all local codes and ordinances. All field wiring shall
conform with the temperature limitations for Type T wire (63°F/
35°C rise).
The main power supply shall be three-phase, three wire. The unit
is factory wired for the voltage shown on the unit’s data plate.
NOTE:Ifsupplyvoltageis208V,allleadsonprimaryoftransformer
TRANS1 must be moved from the 230V to the 208V tap.
Mainpowerwiringshouldbesizedfortheminimumwireampacity
shown on the unit’s database. 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
sizetoprevent excessivevoltagedrop. Wiresshouldbesizedfora
maximum of 3% voltage drop.
T O AVOID PROPERTY DAMAGE OR PERSONAL INJURY DUE TO FIRE , USE
ONLY COPPER CONDUCTORS .
CAUTION
T O PREVENT IMPROPER AND DANGEROUS OPERATION DUE TO WIRING
ERRORS , LABEL ALL WIRES PRIOR TO DISCONNECTION WHEN SERVICING
CONTROLS . V ERIFY PROPER OPERATION AFTER SERVICING .
CAUTION
NOTE: A weather-tight disconnect switch, properly sized for the
unittotalload, mustbefieldorfactoryinstalled. An external field
supplied disconnect may be mounted on the exterior panel.
Ensure the data plate is not covered by the field-supplied
disconnect switch.
• Some disconnect switches are not fused. Protect the
powerleadsatthepointofdistributioninaccordancewith
the unit data plate.
• Theunitmustbeelectricallygroundedinaccordancewith
localcodesor,intheabsenceoflocalcodes,withthelatest
edition of the National Electrical Code (ANSI-NFPA 70). A
ground lug is provided for this purpose. Size grounding
conductorinaccordancewithTable250-95oftheNational
ElectricalCode. Donotusethegroundlugforconnecting
a neutral conductor.
• Connect power wiring to the electrical middle contactor
within the main control box of power block, if equipped.
Low Voltage
Terminal Strip
Thermostat wiring
for all units
connect to low
voltage strip
Ground
Lug
Line voltage connects
to power block on
Coolers, 230V Gas
Packs, and 2 Speed
Models.
Line voltage connects
to middle contactor
on 460v and 575v
Gas Packs
(or power block
if equipped)
Power Block -
(Coolers, 230V Gas
Packs, and 2 Speed
Models)
Field wiring enters
from this direction
POWER AND LOW VOLTAGE BLOCK LOCATIONS

9
F AILURE OF UNIT DUE TO OPERATION ON IMPROPER LINE VOLTAGE OR
WITH EXCESSIVE PHASE UNBALANCE CONSTITUTES PRODUCT ABUSE AND
WILL VOID YOUR WARRANTY AND MAY CAUSE SEVERE DAMAGE TO THE
UNIT ELECTRICAL COMPONENTS .
WARNING
AREAS WITHOUT CONVENIENCE OUTLET
It is recommended that an independent 115V power source be
brought to the vicinity of the roof top unit for portable lights and
tools used by the service mechanic.
NOTE: Refer to local codes for requirements. These outlets can
also be factory installed.
UNITS INSTALLED ON ROOF TOPS
Main power and low voltage wiring may enter the unit through
the side or through the roof curb. Install conduit connectors at
the desired entrance locations. External connectors must be
weatherproof. Allholesinthe unit base mustbe sealed(including
those around conduit nuts) to prevent water leakage into build-
ing. All required conduit and fittings are to be field supplied.
Supplyvoltagetoroof topunitmustnotvarybymorethan 10%of
the value indicated on the unit data plate. Phase voltage unbal-
ance must not exceed 2%. Contact your local power company for
correction of improper voltage or phase unbalance.
ELECTRICAL ENTRANCE LOCATIONS
Unit is equipped with a LowVoltage Terminal Block andhas Single
Point wiring to the contactor.
LOW VOLTAGE CONTROL WIRING
1. A 24V thermostat must be installed for unit operation. It
may be purchased with the unit or field -supplied.
Thermostatsmay beprogrammableor electromechanical
as required.
2. Locate thermostat or remote sensor in the conditioned
space where it will sense average temperature. Do not
locate the device where it may be directly exposed to
supply air, sunlight or other sources of heat. Follow
installation instructions packaged with the thermostat.
3. Use #18 AWG wire for 24V control wiring runs not
exceeding75feet.Use#16AWGwirefor24Vcontrolwiring
runs not exceeding 125 feet. Use #14 AWG wire for 24V
control wiring runs not exceeding 200 feet. Low voltage
wiringmaybeNationalElectricalCode(NEC)Class2where
permitted by local codes.
4. Route thermostat wires from sub-base terminals to the
unit. Control wiring should enter through the duct panel
(dimplemarksentrancelocation).Connectthermostatand
any accessory wiring tolow voltage terminal block TB1 in
the main control box.
NOTE: Field-supplied conduit may need to be installed
depending on unit/curb configuration. Use #18 AWG solid
conductor wire whenever connecting thermostat wires to
terminals on sub-base. DO NOT use larger than #18 AWG wire. A
transition to #18 AWG wire may be required before entering
thermostat sub-base.
NOTE: Refer to unit wiring diagrams for thermostat hookups.
GASSUPPLYPIPING
T O PREVENT PERSONAL INJURY OR DEATH DUE TO IMPROPER
INSTALLATION , ADJUSTMENT , ALTERATION , SERVICE OR MAINTENANCE ,
REFER TO THIS MANUAL . F OR ADDITIONAL ASSISTANCE OR
INFORMATION , CONSULT A QUALIFIED INSTALLER , SERVICE AGENCY OR
THE GAS SUPPLIER .
WARNING
IMPORTANT NOTE: This unit is factory set to operate on natural
gas at the altitudes shown on the rating plate.
T O PREVENT PROPERTY DAMAGE , PERSONAL INJURY OR DEATH WHEN
EITHER USING PROPANE GAS ALONE OR AT HIGHER ALTITUDES , OBTAIN
AND INSTALL THE PROPER CONVERSION KIT ( S ). F AILURE TO DO SO CAN
RESULT IN UNSATISFACTORY OPERATION AND / OR EQUIPMENT DAMAGE .
H
IGH ALTITUDE KITS ARE FOR U.S. I NSTALLATIONS ONLY AND ARE NOT
APPROVED FOR USE IN C ANADA .
WARNING
The rating plate is stamped with the model number, type of gas
andgasinput rating.Makesuretheunit isequippedto operateon
thetypeofgasavailable.Conversiontopropane(LP)gasispermit-
ted with the use of the factory authorized conversion kit (see the
unit Technical Manual for the appropriate kit). For High Altitude
derates, refer to the latest edition of the National Fuel Gas Code
NFPA 54/ANSI Z223.1.

10
NATURAL Min. 5.0" W.C., Max. 10.0" W.C.
PROPANE Min.11.0" W.C.,Max.14.0"W.C.
INLET GAS PRESSURE
Inlet Gas Pressure Must Not Exceed the Maximum Value Shown in Table Above.
Theminimumsupply pressureshouldnotvaryfromthatshownin
the table above because this could prevent the unit from having
dependable ignition. In addition, gas input to the burners must
not exceed the rated input shown on the rating plate. Overfiring
of the unit could result in premature heat exchanger failure.
PIPING
IMPORTANT NOTE: To avoid possible unsatisfactory operation or
equipment damage due to under firing of equipment, do not un-
dersizethenatural/propanegaspipingfromthemeter/tanktothe
unit. When sizing a trunk line, include all appliances on that line
that could be operated simultaneously.
The rating plate is stamped with the model number, type of gas
andgasinput rating.Makesuretheunitisequippedtooperateon
the type of gas available. The gas line installation must comply
with local codes, or in the absence of local codes, with the latest
edition of the National Fuel Gas Code NFPA 54/ANSI Z223.1.
Natural Gas Connection
1/2 3/4 1 1 1/4 1 1 /2
10 132 278 520 1050 1600
20 92 190 350 730 1100
30 73 152 285 590 980
40 63 130 245 500 760
50 56 115 215 440 670
60 50 105 195 400 610
70 46 96 180 370 560
80 43 90 170 350 530
90 40 84 160 320 490
100 38 79 150 305 460
Pressure= .50 PSIG or less and Pressure Drop of 0.3" W.C.
(Based on 0.60 Specific Gravity Gas)
Natural Gas Capacity of Pipe
in Cubic Feet of Gas Per Hour (CFH)
Nominal Black Pipe Size (inches)
Length of
Pipe in Feet
HeatingValue of Gas(BTU/Cubic Foot
CFH= BTUH Furnace Input
Refer to the Proper Piping Practice drawing for the general layout
at the unit. The following rules apply:
1. Useblack iron pipe andfittingsforthe supplypiping. The
use of a flex connector and/or copper piping is permitted
aslong as it is in agreement with local codes.
2. Use pipe joint compound on male threads only. Pipe joint
compoundmustberesistanttotheactionofthefuelused.
3. Use ground joint unions.
4. Install a drip leg to trap dirt and moisture before it can
enter the gas valve. The drip leg must be a minimum of
three inches long.
5. Use two pipe wrenches when making connection to the
gas valve to keep it from turning.
6. Install a manual shut-off valve in a convenient location
(within six feet of unit) between the meter and the unit.
7. Tighten all joints securely.
8. Theunitmust be connected to thebuildingpipingby one
of the following methods:
• Rigid metallic pipe and fittings
• Semirigid metallic tubing and metallic fittings (Aluminum
alloy tubing must not be used in exterior locations)
• Listed gasapplianceconnectors used inaccordancewith
theterms of their listing that arecompletelyinthesame
room as the equipment
• In the prior two methods above the connector or tubing
must be protected from physical and thermal damage.
Aluminum alloy tubing and connectors must be coated
toprotectagainstexternalcorrosionwhenincontactwith
masonry, plaster or insulation oraresubject torepeated
wettings by liquids(water- not rainwater, detergents or
sewage).
46-1/10”
GAS INLET LOCATION (3/4” NPT)
46-1/10”46-1/10”
74-11/12”
HOOD LOCATED
INSIDE HEAT SECTION
DURING SHIPPING
DOOR
PROVIDE
CLEARANCE
FOR REMOVAL OF
ACCESS PANELS
DRIP LEG
GROUND
JOINT
UNION
MANUAL
SHUT OFF
VALVE
PROPER PIPING PRACTICE

11
NOTE: The unit gas supply entrance is factory sealed with plugs.
Keep plugs in place until gas supply is ready to be installed. Once
ready, replace the plugs with the supplied grommets and install
gas supply line.
GAS PIPING CHECKS
T O PREVENT PROPERTY DAMAGE OR PERSONAL INJURY DUE TO FIRE ,
THE FOLLOWING INSTRUCTIONS MUST BE PERFORMED REGARDING GAS
CONNECTIONS AND PRESSURE TESTING :
• T
HE UNIT AND ITS GAS CONNECTIONS MUST BE LEAK TESTED
BEFORE PLACING IN OPERATION . B ECAUSE OF THE DANGER OF
EXPLOSION OR FIRE , NEVER USE A MATCH OR OPEN FLAME TO TEST
FOR LEAKS . N EVER EXCEED SPECIFIED PRESSURES FOR TESTING .
H
IGHER PRESSURE MAY DAMAGE GAS VALVE AND CAUSE
OVERFIRING WHICH MAY RESULT IN PREMATURE HEAT EXCHANGE
FAILURE .
• T
HIS UNIT AND ITS SHUT - OFF VALVE MUST BE DISCONNECTED FROM
THE GAS SUPPLY DURING ANY PRESSURE TESTING OF THAT SYSTEM
AT TEST PRESSURES IN EXCESS OF 1/2 PSIG (3.48 K P A ).
• T
HIS UNIT MUST BE ISOLATED FROM THE GAS SUPPLY SYSTEM BY
CLOSING ITS MANUAL SHUT - OFF VALVE DURING ANY PRESSURE
TESTING OF THE GAS SUPPLY PIPING SYSTEM AT TEST PRESSURES
EQUAL TO OR LESS THAN 1/2 PSIG (3.48 K P A ).
CAUTION
T O AVOID PROPERTY DAMAGE OR PERSONAL INJURY , BE SURE THERE IS
IN THE VICINITY DURING AIR BLEEDING . NO OPEN FLAME
WARNING
There will be air in the gas supply line after testing for leaks on a
new installation. Therefore, the air must be bled from the line by
looseningthegroundjointunionuntilpuregasisexpelled.Tighten
unionand waitfor fiveminutesuntil all gashas beendissipatedin
the air. Be certain there is no open flame in the vicinity during air
bleeding procedure. The unit is placed in operation by closing the
main electrical disconnect switch for the unit.
PROPANEGASINSTALLATIONS
T O AVOID PROPERTY DAMAGE , PERSONAL INJURY OR DEATH DUE TO
FIRE OR EXPLOSION CAUSED BY A PROPANE GAS LEAK , INSTALL A GAS
DETECTING WARNING DEVICE . S INCE RUST CAN REDUCE THE LEVEL OF
ODORANT IN PROPANE GAS , A GAS DETECTING WARNING DEVICE IS THE
ONLY RELIABLE WAY TO DETECT A PROPANE GAS LEAK . C ONTACT A
LOCAL PROPANE GAS SUPPLIER ABOUT INSTALLING A GAS DETECTING
WARNING DEVICE .
WARNING
IMPORTANT NOTE: Propane gas conversion kits must be installed
to convert units to propane gas.
All propane gas equipment mustconform to the safety standards
oftheNationalBoardofFireUnderwriters(SeeNBFUManual 58).
Line pressure 11.3 - 14” w.c.
For satisfactory operation, propane gas manifold pressure must
be within 9.7 - 10.3 inches w.c. for high fire and within 6.7 - 7.3
inches w.c. low fire at the manifold with all gas appliances in op-
eration. Maintaining proper gas pressure depends on three main
factors:
1. Vaporization rate, which depends on (a) temperature of
theliquid,and(b) wettedsurfaceareaofthecontaineror
containers.
2. Proper pressure regulation.
3. Pressure drop in lines between regulators, and between
second stage regulator and the appliance. Pipe size
required will depend on length of pipe run and total load
of all appliances.
TANKS AND PIPING
Complete information regarding tank sizing for vaporization,
recommended regulator settings and pipe sizing is available
frommostregulatormanufacturersandpropanegassuppliers.
Since propane gas will quickly dissolve white lead or most
standardcommercialcompounds,specialpipedope must be
used. Shellac base compounds resistant to the actions of
liquefiedpetroleumgasessuchasGasolac®,Stalactic®,Clyde’s®
or John Crane®are satisfactory.
See following figure for typical propane gas piping.
200 PSIG
Maximum
5 to 15 PSIG
(20 PSIG Max.) Continuous
11" W.C.
Second Stage
Regulator
First Stage
Regulator
TYPICAL PROPANE GAS PIPING
ROOF TOP LOCATION AND INSTALLATION
The gas supply piping location and installation for roof top units
mustbeinaccordancewithlocalcodesor, in theabsenceoflocals
codes, with ordinances of the latest edition of the National Fuel
Gas Code (ANSI Z223.1).
A manual gas shut off valve must be field installed external to the
roof top unit. In addition, a drip leg must be installed near the
inlet connection. A ground joint union connection is required be-
tween the external shut off valve and the unit connection to the
gas valve to permit removal of the burner assembly for servicing.
1. Route gas piping to unit so that it does not interfere with
the removal of access panels. Support and align piping to
preventstrainsormisalignmentofthemanifoldassembly.

12
2. All units are furnished with standard female NPT pipe
connections. Connection pipe size is 3/4" NPT. The size of
the gas supply piping to the unit must be based on length
ofrun,numberofunitsonthesystem,gascharacteristics,
BTUrequirementandavailablesupplypressure.Allpiping
must be done in accordance with local codes or, in the
absence of local codes, with the latest edition of the
National Fuel Gas Code (ANSI Z223.1).
NOTE: The gas connection size at the unit does NOT
establish the size of the supply line.
3. These units are designed for either natural or propane
(LP) gas and are specifically constructed at the factory for
onlyoneofthesefuels.ThefuelsareNOTinterchangeable.
However, the furnace can be converted in the field from
natural gas to LP gas with the appropriate factory kit (see
unit Technical Manual for the appropriate kit). Only a
qualifiedcontractor,experiencedwithnaturalandpropane
gas systems, should attempt conversion. Kit instructions
must be followed closely to assure safe and reliable unit
operation.
4. With all units on a common line operating under full fire,
natural gas main supply pressure should be adjusted to
approximately7.0"w.c.,measuredatthe unitgasvalve.If
the gas pressure at the unit is greater than 10.5" w.c., the
contractor must furnish and install an external type
positive shut off service pressure regulator. The unit will
notfunctionsatisfactorilyifsupplygaspressureislessthan
5.5" w.c. or greater than 10.5" w.c..
NOTE: A minimum horizontal distance of 48" between
the regulator and the furnace flue discharge is required.
5. With all units on a common line operating under full LP
gasmainsupplypressureshouldbeatleast11.0"w.c.and
must be no greater than 14.0" w.c., measured at the unit
gas valve. Unit will not function satisfactorily if supply gas
pressure is less than 11.0" w.c. or greater than 14.0" w.c..
6. All pipe connections should be sealed with a pipe thread
compound, which is resistant to the fuel used with the
furnace. A soapy water solution should be used to check
all joints for leaks. A 1/8" NPT plugged tap is located on
theenteringsideofthegasvalvefortestgaugeconnection
to measure supply (main) gas pressure. Another 1/8" tap
is provided on the side of the manifold for checking
manifold pressure.
T HIS UNIT AND ITS INDIVIDUAL SHUTOFF VALVE MUST BE
DISCONNECTED
FROM THE GAS SUPPLY SYSTEM DURING ANY
PRESSURE TESTING OF THAT SYSTEM AT TEST PRESSURES IN EXCESS OF
1/2 PSIG (13.8”
W . C .).
WARNING
T HIS UNIT MUST BE ISOLATED FROM THE GAS SUPPLY PIPING SYSTEM
BY CLOSING ITS INDIVIDUAL MANUAL SHUTOFF VALVE DURING ANY
PRESSURE TESTING EQUAL TO OR LESS THAN 1/2 PSIG.
CAUTION
7. There must be no obstruction to prevent the flow of
combustionandventilatingair.Aventstackisnotrequired
and must never be used. The power ventor will supply an
adequate amount of combustion air as long as the air
passageways are kept free of any obstructions and the
recommended external unit clearances are maintained.
CIRCULATINGAIRAND FILTERS
DUCTWORK
The supply duct should be provided with an access panel large
enough to inspect the air chamber downstream of the heat ex-
changer. A cover should be tightly attached to prevent air leaks.
Ductwork dimensions are shown in the roof curb installation
manual.
If desired, supply and return duct connections to the unit may be
made with flexible connections to reduce possible unit operating
sound transmission.
VENTING
NOTE: Venting is self-contained.
CONDENSATEDRAINCONNECTION
CONDENSATE DRAIN CONNECTION
A 1” female NPT drain connection is supplied on the side of the
unit and a 1” male NPT on the bottom of the drain pan for con-
densatepiping. Anexternal trapmust beinstalledfor propercon-
densate drainage.
UNIT 2" MINIMUM
FLEXIBLE
TUBING-HOSE
OR PIPE 3" MINIMUM
A
POSITIVE LIQUID
SEAL IS REQUIRED
DRAIN CONNECTION
Install condensate drain trap as shown. Use 1" drain line and fit-
tings or larger. Do not operate without trap.
HORIZONTAL DRAIN
Drainage ofcondensatedirectlyontotheroofmay be acceptable;
refer to local code. It is recommended that a small drip pad of
either stone, mortar, wood or metal be provided to prevent any
possible damage to the roof.
CLEANING
Due to the fact that drain pans in any air conditioning unit
will have some moisture in them, algae and fungus will
grow due to airborne bacteria and spores. Periodic clean-
ing is necessary to prevent this build-up from plugging the
drain.

13
STARTUP,ADJUSTMENTS,ANDCHECKS
HIGH VOLTAGE!
T O AVOID PERSONAL INJURY OR DEATH DUE TO
ELECTRICAL SHOCK , BOND THE FRAME OF THIS UNIT TO
THE BUILDING ELECTRICAL GROUND BY USE OF THE
GROUNDING TERMINAL PROVIDED OR OTHER
ACCEPTABLE MEANS . D ISCONNECT ALL POWER BEFORE
SERVICING OR INSTALLING THIS UNIT .
WARNING
PRE-STARTUP INSTRUCTIONS - GENERAL
T O PREVENT PROPERTY DAMAGE OR PERSONAL INJURY , D O NOT START
THE UNIT UNTIL ALL NECESSARY PRE - CHECKS AND TEST HAVE BEEN
PERFORMED .
CAUTION
PriortothebeginningofStartup,Adjustments,and Checksproce-
dures, the following steps should be completed in the building.
MOVING MACHINERY HAZARD!
T
O PREVENT POSSIBLE PERSONAL INJURY OR DEATH , DISCONNECT
POWER TO THE UNIT AND PADLOCK IN THE “OFF” POSITION BEFORE
SERVICING FANS .
WARNING
This unit is equipped with an electronic ignition device to auto-
matically light the main burners. It also has a power vent blower
to exhaust combustion products.
On new installations, or if a major component has been replaced,
the operation of the unit must be checked.
Check unit operation as outlined in the following instructions. If
any sparking, odors, or unusual sounds are encountered, shut off
electrical power and recheck for wiring errors, or obstructions in
or near the blower motors. Duct covers must be removed before
operating unit.
The Startup, Adjustments, and Checks procedure provides a step-
by-stepsequencewhich,iffollowed,willassuretheproperstartup
of the equipment in the minimum amount of time. Air balancing
of duct system is not considered part of this procedure. However,
itisanimportantphaseofanyairconditioningsystemstartupand
shouldbeperformeduponcompletionoftheStartup,Adjustments,
andChecksprocedure.TheStartup,Adjustments,andCheckspro-
cedureatoutsideambientsbelow55°Fshouldbelimitedtoareadi-
nesscheckoftherefrigerationsystemwiththerequiredfinalcheck
and calibration left to be completed when the outside ambient
rises above 55°F.
TEMPORARY HEATING ORCOOLING
Iftheunitistobeusedfortemporaryheatingorcooling,a“Startup,
Adjustments, and Checks” must first be performed in accordance
withthismanual.Failuretocomplywiththisrequirementwillvoid
the warranty. After the machines are used for temporary heating
or cooling, inspect the coils, fans, and motors for unacceptable
levels of construction dust and dirt and install new filters.
CONTRACTOR RESPONSIBILITY
The installing contractor must be certain that:
• All supply and return air ductwork is in place, properly
sealed, and corresponds with installation instructions.
• All thermostats are mounted and wired in accordance
with installation instructions.
• All electric power, all gas, hot water or steam line
connections, and the condensate drain installation have
been made to each unit on the job. These main supply
linesmustbefunctionalandcapableofoperatingallunits
simultaneously.
• Requirements are met for venting and combution air.
• Air filters are in place.
• Input rate and temperature rise are adjusted per rating
plate.
ROOF CURB INSTALLATION CHECK
Inspect the roof curb for correct installation. The unit and curb
assembly should be level. Inspect the flashing of the roof mount-
ing curb to the roof, especially at the corners, for good workman-
ship. Also check for leaks around gaskets. Note any deficiencies in
a separate report and forward to the contractor.
OBSTRUCTIONS, FAN CLEARANCE AND WIRING
Remove any extraneous construction and shipping materials that
may be found during this procedure. Rotate all fans manually to
check for proper clearances and that they rotate freely. Check for
bolts and screws that may have jarred loose during shipment to
the job site. Retighten if necessary. Re-tighten all electrical con-
nections.
FIELD DUCT CONNECTIONS
Verify that all duct connections are tight and that there is no air
bypass between supply and return.
FILTER SECTION CHECK
Removefiltersectionaccesspanelsandcheckthatfiltersareprop-
erly installed. Note airflow arrows on filter frames.
PRE-STARTUP PRECAUTIONS
It is important to your safety that the unit has been properly
groundedduringinstallation.Check groundlugconnectioninmain
control box for tightness prior to closing circuit breaker or discon-
nect switch. Verify that supply voltage on line side of disconnect
agrees with voltage on unit identification plate and is within the
utilizationvoltagerangeasindicatedinAppendixCElectricalData.
System Voltage - That nominal voltage value assigned to a circuit
or system for the purpose of designating its voltage class.
Nameplate Voltage - That voltage assigned to a piece of equip-
ment for the purpose of designating its voltage class and for the
purpose of defining the minimum and maximum voltage at which
the equipment will operate.

14
UtilizationVoltage- Thevoltageofthelineterminalsoftheequip-
ment at which the equipment must give fully satisfactory perfor-
mance. Once it is established that supply voltage will be main-
tained within the utilization range under all system conditions,
check and calculate if an unbalanced condition exists between
phases. Calculate percent voltage unbalance as follows:
Three Phase Models
3) PERCENT VOLTAGE
UNBALANCE
2) MAXIMUM VOLTAGE DEVIATIONS
FROM AVERAGE VOLTAGE
1) AVERAGE VOLTAGE
HOW TO USE THE FORMULA:
EXAMPLE: With voltage of 220, 216, and 213
1) Average Voltage = 220+216+213=649 / 3 = 216
2) Maximum Voltage Deviations from Average Voltage = 220 - 216 = 4
3) Percent Voltage Unbalance = 100 x = = 1.8%
Percent voltage unbalance MUST NOT exceed 2%.
4
216 400
216
= 100 X
CONTROL VOLTAGE CHECK
With disconnect switch in the open “OFF” position, disconnect
bluewirefromlowvoltagetransformerTRANS1.Closethediscon-
nect switch to energize TRANS1 control transformer. Check pri-
mary and secondary (24V) of control transformer TRANS1.
AIRFLOWADJUSTMENTS
NOTE: For2SpeedModels, airflow adjustments mustbe madeon
high speed, i.e., 2nd stage cooling or in heat mode.
The drive on the supply fan is typically set in the middle of the
RPM range. The drive motor sheave pitch diameter is field adjust-
able for the required airflow. Refer to the following “Drive
Adjustments” section.
Whenthefinaladjustmentsarecomplete,thecurrentdrawofthe
motor should be checked and compared to the full load current
rating of the motor. The amperage must not exceed the service
factor stamped on the motor nameplate. The total airflow must
notbelessthan that requiredforoperationoftheelectricheaters
or the furnace.
Ifaneconomizerisinstalled,checktheunitoperatingbalancewith
theeconomizeratfulloutsideairandatminimumoutsideair. Upon
completion of the air flow balancing, we recommend replacing
the variable pitched motor sheave with a properly-sized fixed
sheave.Amatchingfixed sheavewillprovidelonger beltandbear-
ing life and vibration free operation. Initially, it is best to have a
variable pitched motor sheave for the purpose of airflow balanc-
ing, but once the balance has been achieved, fixed sheaves main-
tain alignment and minimize vibration more effectively. For direct
drive units, move green wire for fan.
NOTE:On“non-twospeedmodels”(two-speedmodelshavea“V”
in the eleventh character of the model number), never run CFM
below 300 CFM per ton. Evaporator freezing or poor unit perfor-
mance is possible.
EVAPORATOR FAN ROTATION CHECK
Checkthat fanrotates clockwise whenviewedfrom thedrive side
of unit and in accordance with rotation arrow shown on blower
housing. If it does not, reverse any two incoming power cables at
Single Point Power Block. In this case, repeat bearing check.
Donotattempttochangeloadside wiring. Internalwiring assures
all motors and compressors will rotate in correct direction once
evaporator fan motor rotation check has been made.
ELECTRICAL INPUT CHECK
Makepreliminarycheckofevaporatorfanamperedrawandverify
that motor nameplate amps are not exceeded. A final check of
amp draw should be made upon completion of air balancing of
the duct system (see Appendix C).
SET EVAPORATOR FAN RPM
ActualRPM’smustbesetandverifiedwithatachometerorstrobe
light. Refer to Appendices A and B for basic unit fan RPM. Refer
also to “Airflow” section of this manual. With disconnect switch
open, disconnect thermostat wires from terminals Y and W. This
willpreventheatingandmechanicalcoolingfromcomingon.Place
ajumperwireacrossterminalsRandGatTB1terminalblock.Close
disconnect switch; evaporator fan motor will operate so RPM can
be checked.
For gas heat units, the airflow must be adjusted so that the air
temperaturerisefalls withintherangesgiven statedon DataPlate
(see Appendix A - Blower Performance).
BELT DRIVE MODELS ONLY
The drive on the supply fan is typically set in the middle of the
RPM range. The drive motor sheave pitch diameter is field adjust-
ablefortherequiredairflow.Referto“MotorSheaveAdjustmens”
section.
Upon completion of the air flow balancing, we recommend re-
placing the variable pitched motor sheave with a properly-sized
fixed sheave.A matchingfixed sheavewill providelonger belt and
bearinglifeandvibrationfreeoperation.Initially,itisbesttohave
avariablepitchedmotorsheaveforthepurposeofairflowbalanc-
ing, but once the balance has been achieved, fixed sheaves main-
tain alignment and minimize vibration more effectively. For direct
drive units, move fan speed wire.
BEARING CHECK
Priortoenergizinganyfans,checkandmakesurethatallsetscrews
are tight so that bearings are properly secured to shafts.
TENSION AND ALIGNMENT ADJUSTMENT
Correct belt tension is very important to the life of your belt. Too
loose a belt will shorten its life; too tight, premature motor and
bearing failure will occur. Check you belt drive for adequate “run-
in” belt tension by measuring the force required to deflect the
belt at the midpoint of the span length. Belt tension force can be
measured using a belt tension gauge, available through most belt
drive manufacturers.

15
SPANLENGTHt
*DEFLECTION
FORCE
h
C
d
H
D
*Apply force to the center of the span.
t = Span length, inches
C = Center distance, inches
D = Larger sheave diameter, inches
d = Smaller sheave diameter, inches
h = Deflection height, inches
DRIVE BELT TENSION ADJUSTMENT
MODEL SHEAVE DIAMETER
(in)
DEFLECTION
(in)
BELT DRIVE Used New
15Ton B,BA Standard 4.3to5.5 5.5+ .5 8.2+ .5 1/4 ± 1/16
20Ton B,BA Standard 4.3to5.5 5.5 + .5 8.2+ .5 1/4 ± 1/16
DEFLECTION
FORCE (lbs)
TYPE
RECOMMENDED POUNDS OF FORCE PER BELT
When new V-belts are installed on a drive the initial tension will
drop rapidly during the first few hours. Check tension frequently
during the first 24 hours of operation. Subsequent retensioning
should fall between the minimum and maximum force. To deter-
mine the deflection distance from the normal position, use a
straightedge or stretch a cord from sheave to sheave to use as a
reference line. On multiple belt drives, an adjacent undeflected
belt can be used as a reference.
MOTORSHEAVEADJUSTMENTS
VL, VM& 2VP VARIABLE PITCH KEY TYPE MOTOR SHEAVES
Thedriving anddrivenmotor sheavesshouldbeinalignmentwith
each other and the shafts parallel.
VL& VMSHEAVES ADJUSTMENT
1. Loosen set screw “B” using a 5/32" Allen key.
2. Making half or full turns from closed position, adjust
sheave pitch diameter for desired speed. DO NOT OPEN
MORE THAN SIX FULL TURNS.
3. Tighten set screw “B” securely over flat.
4. Carefully put on belts and adjust belt tension. DO NOT
FORCE BELTS OVER GROOVES.
5. Ensureallkeysareinplaceandthesetscrewstightbefore
starting drive. Recheck set screws and belt tension after
24 hours service.
NOTE: Future adjustments should be made by loosening the belt
tension and increasing or decreasing the pitch diameter of the
sheavebyhalforfullturnsasrequired.Readjustbelttensionbefore
starting drive.
C
B
VL & VM
NOTE: Do not operate sheave with flange projecting beyond the
hub end.
GASSYSTEM CHECK
Pre-Operation Checks
1. Close the manual gas valve external to the unit.
2. Turn off the electrical power supply to the unit.
3. Set the room thermostat to its lowest possible setting.
4. Remove the heat exchanger door on the side of the unit
by removing screws.
5. This unit is equipped with an ignition device which
automatically lights the main burner. DO NOT try to light
burner by any other method.
6. Movethe gascontrolvalve switch to the OFFposition. Do
not force.
7. Wait five minutes to clear out any gas.
8. Smellforgas,including neartheground.Thisisimportant
becausesometypesofgasareheavierthanair.Ifyouhave
waited five minutes and you do smell gas, immediately
follow the warnings on page 3 of this manual. If having
waited for five minutes and no gas smell is noted, move
the gas control valve switch to the ON position.
9. Replace the heat exchanger door on the side of the unit.
10. Open the manual gas valve external to the unit.
11. Turn on the electrical power supply to the unit.
12. Set the thermostat to desired setting.
GAS SUPPLY PRESSURES & REGULATOR ADJUSTMENTS
S HOULD OVERHEATING OCCUR OR THE GAS SUPPLY FAIL TO SHUT OFF ,
TURN OFF THE MANUAL GAS SHUTOFF VALVE EXTERNAL TO THE UNIT
BEFORE TURNING OFF THE ELECTRICAL SUPPLY .
WARNING

16
T O AVOID PROPERTY DAMAGE , PERSONAL INJURY OR DEATH , DO NOT
FIRE GAS UNIT WITH FLUE BOX COVER REMOVED .
WARNING
NOTE: Except during brief periods when gas pressures are being
measuredbyqualifiedservicepersonnel,thefurnaceaccesspanel
mustalways besecuredin place whenthefurnaceis in operation.
An inspection port in the access panel is provided to monitor the
flame.
The first step in checking out the gas-fired furnace is to test the
gas supplypipingtotheunitfortightnessandpurgethesystem of
air using methods outlined in the latest edition of the National
FuelGasCodeANSIZ223.1. Verifythat the disconnectswitchis in
the“OFF”position. Asoapywatersolutionshouldbeusedtocheck
for gas leaks. Since the unit is subject to considerable jarring dur-
ing shipment, it is extremely important that all gas connections
and joints be tested for tightness. Gas piping downstream from
the unit inlet should be checked for leaks during the subsequent
sequence check.
Thesupplygaspressure should beadjusted to 7.0" w.c. on natural
gas and 11.0" on LP gas with the gas burners operating. If there is
more than one unit on a common gas line, the pressures should
be checked with all units under full fire. A supply pressure tap is
provided on the upstream side of the gas valve. A manifold pres-
sure tap is provided on the manifold. The normal manifold pres-
sure for full input is 3.5" w.c. on natural gas and 10.0" w.c. for
propane gas. Minimum gas supply pressure is5.5" w.c. for natural
gasand11.0"forpropanegas.Inordertoobtainrating,gassupply
pressure must be 11.0" w.c. for propane gas.
The pressure regulator on LP gas models is adjusted for 10.0" w.c.
manifold pressure and is intended to prevent over-firing only. Do
not attempt adjustment of the built-in pressure regulator unless
thesupplypressureisatleast7.0"w.c.onnaturalgasor14.0"w.c.
on propane gas. Check the location of the ignition electrode and
the flame sensor for correct gap setting.
Flame
Sensor
Ignitor
NATURAL PROPANE (LP)
350,000 7 50,000 #30 #48
400,000 8 50,000 #30 #48
GASORIFICES
MAXIMUM
INPUT
(BTUH)
NUMBER
of
BURNERS
MAXIMUM
BTUH/BURNER
HEAT EXCHANGER AND BURNER ORIFICE SPECIFICATIONS
NOTE:Gasapplianceslocatedmorethan2000feetabovesealevel
must be derated 4% per 1000 feet of total elevation and that
variance in gas heating value and specific gravity require change
inmanifoldpressuretoobtainrating,itismandatorythattheinput
beadjustedattheinstallationsite.Allinstallationsshouldbemade
asoutlinedinthelatesteditionoftheNationalFuelGasCodeANSI
Z223.1,section“ProceduresToBeFollowedTo PlaceAnAppliance
in Operation”. Refer also to the “User’s Information Manual”
suppliedwiththeunitforadditionalinformationonthegasfurnace.
Gas Supply And Manifold Check
Gassupplypressureandmanifoldpressurewiththeburnersoper-
ating must be asspecified on the rating plate.
Gas Inlet Pressure Check
Gasinletpressuremustbechecked and adjusted in accordance to
the type of fuel being consumed.
With Power And Gas Off:
1. Connect a water manometer or adequate gauge to the
inlet pressure tap of the gas valve.
Inlet gas pressure can also be measured by removing the
cap from the dripleg and installing a predrilled cap with a
hose fitting.
With Power And Gas On:
2. Put unit into heating cycle and turn on all other gas
consuming appliances.
NATURAL Min. 5.0" W.C., Max. 10.0" W.C.
PROPANE Min.11.0" W.C.,Max.14.0"W.C.
INLET GAS PRESSURE
NOTE: Inlet Gas Pressure Must Not Exceed the Maximum Value
Shown.
Ifoperatingpressuresdifferfromabove,makenecessarypressure
regulatoradjustments,checkpipingsize,etc.,and/orconsultwith
local utility.
Manifold Pressure Check
The gas valve has a tapped opening to facilitate measurement of
themanifoldpressure.A“U”Tubemanometerhavingascalerange
from 0 to 12 inches of water should be used for this measure-
ment. The manifold pressure must be measured with the burners
operating.

17
To adjust the pressure regulator, remove the adjustment screw or
cover on the gas valve. Turn out (counterclockwise) to decrease
pressure,turnin(clockwise)toincreasepressure.Onlysmallvaria-
tionsingasflow should bemadebymeansofthepressure regula-
toradjustment. In no case should the finalmanifoldpressure vary
more than plus or minus 0.3 incheswater column from the speci-
fiednominal pressure.Any majorchanges in flowshould be made
by changing the size of the burner orifices. The measured input
rate to the furnace must not exceed the rating specified on the
unit rating plate.
For natural gas, the manifold pressure must be between 3.2 and
3.8inchesw.c. (3.5 nominal) forhigh fireand between1.7and 2.3
inches w.c. (2.0 nominal) for low fire.
For propane gas, the manifold pressure must be between 9.7 and
10.3 inches w.c. (10.0 nominal) for high fire and between 6.7 and
7.3 inches w.c. (7.0 nominal) for low fire.
Gas Input (Natural Gas Only) Check
It is the responsibility of the contractor to adjust the gas input to
the unit.
To measure the gas input use a gas meter and proceed as
follows:
1. Turnoffgassupply to allotherappliancesexcepttheunit.
2. With the unit operating, time the smallest dial on the
meterforonecompleterevolution.If this isa 2 cubic foot
dial,divide the seconds by2; if itis a1 cubic foot dial, use
the seconds as is. This gives the seconds per cubic foot of
gas being delivered to the unit.
3. INPUT=GAS HTG VALUE x 3600 / SEC. PER CUBIC FOOT
Example: Natural gas with a heating value of 1000 BTU per cubic
footand 34 secondspercubicfootas determinedbyStep2, then:
Input = 1000 x 3600 / 34 = 106,000 BTU per Hour. NOTE:
BTU content of the gas should be obtained from the gas
supplier. This measured input must not be greater than
shown on the unit rating plate.
Adjust input rate by varying the adjustment of the gas pressure
regulator on the gas valve. All adjustments must be made with
furnace operating at high fire and at normal operating tempera-
ture. A manometer should be connected to the gas valve to verify
pressure is within the specified range (see following figures for
manometerconnections). Clockwiserotationofthepressureregu-
latorscrewincreasespressure andgasflowrate.Turnscrewcoun-
terclockwise to decrease pressure and gas flow rate. After adjust-
mentthefurnacetemperaturerisemustbewithintherangespeci-
fied on the unit data plate. NOTE: Thermal efficiency of the fur-
nace is a product efficiency rating determined under continuous
operating conditions independent of any installed system.
Pressure Regulator
Adjustment
(Under Cap Screw)
Gas Valve
On/Off
Selector
Switch
INLET OUTLET
Inlet Pressure
Tap
Outlet Pressure
Tap
WHITE-RODGERS 36G22 - SINGLE STAGE
Inlet
Pressure Boss
Low Fire
Regulator Adjust
Manometer
Manometer
Hose
High Fire Regulator
Adjust Regulator
Vent
Outlet
Pressure Boss
Open t
o
Atmosphere
WHITE-RODGERS 36G54 (2-STAGE) CONNECTED TO MANOMETER
PRESSURE ADJUSTMENTS
TO CONNECT MANOMETER TO GAS VALVE:
1. Backoutletpressuretestscrew(inlet/outletpressureboss)
outoneturn(counterclockwise, notmorethan one turn).
2. Attachahoseand manometertotheoutletpressureboss
of the valve.
TO REMOVE MANOMETER FROM GAS VALVE:
1. Remove manometer hose from outlet pressure boss.
2. Turn outlet pressure test screw in to seal pressure port
(clockwise, 7 in-lb. minimum).
3. Turn on electrical power and gas supply to the system.
4. Turn on system power and energize valve.
5. Using a leak detection solution or soap suds, check for
leaks at pressure boss screw. Bubbles forming indicate a
leak. SHUT OFF GAS AND FIX ALL LEAKS IMMEDIATELY.
T O PREVENT UNRELIABLE OPERATION OR EQUIPMENT DAMAGE , THE
GAS MANIFOLD PRESSURE MUST BE AS SPECIFIED ON THE UNIT
RATING PLATE . O NLY MINOR ADJUSTMENTS SHOULD BE MADE BY
ADJUSTING THE GAS VALVE PRESSURE REGULATOR .
CAUTION

18
4. Relight all other appliances turned off in step 1. Be sure all
pilot burners are operating.
Main Burner Flame Check
Flames should be stable, soft and blue (dust may cause orange
tips but they must not be yellow) and extending directly outward
from the burner without curling, floating or lifting off.
Temperature Rise Check
Checkthetemperaturerisethrough the unit byplacing thermom-
eters in supply and return air registers as close to the unit as pos-
sible. Thermometers must not be able to sample temperature di-
rectly from the unit heat exchangers, or false readings could be
obtained.
1. All registers must be open; all duct dampers must be in
their final (fully or partially open) position and the unit
operated for 15 minutes on HIGH FIRE before taking
readings.
2. The temperature rise must be within the range specified
on the rating plate.
NOTE:Airtemperatureriseisthetemperaturedifferencebetween
supply and return air.
With aproperly designedsystem, theproperamountof tempera-
ture rise will normally be obtained when the unit is operated at
rated input with the recommended blower speed.
If the correct amount of temperature rise is not obtained, it may
be necessaryto change the blower speed. A higher blower speed
will lower the temperature rise. A slower blower speed will in-
crease the temperature rise.
NOTE: Blower speed MUST be set to give the correct air
temperature rise through the unit as marked on the rating plate.
NORMALSEQUENCEOFOPERATION-HEATING
This unit has one (RS) Manual Reset Limit Control Switch. Check
the limit to make sure it has not tripped. The limit may arrive at
the job site tripped as a result of shipping shock.
If the ventor motor comes on, but the unit does not attempt igni-
tion, check if the ALS (Automatic Reset High Limit Control Switch)
requires resetting.
1. With electricity and gas turned on, the system switch in
the “HEAT” or “AUTO” position and the fan switch in the
“AUTO” position, the thermostat will close the circuit
between unit terminals R and W (R-W) when the
temperature falls below the thermostat setting.
2. D1 on IIC energizes relay IDMR.
3. Relay IDMR energizes the ventor motor IDM.
4. OperationoftheventmotorclosesthepressureswitchPS
located in the burner compartment. the control then
initiates a 15-second pre-purge time delay. During this
period, the ventor motor will clear the combustion
chamber of any residual gas.
5. After the pre-purge period, the ignition control energizes
the Wl-C gas valve and simultaneously initiates a “three
(3)-try” spark ignition sequence.
6. When the burners are ignited, a minimum four (4) micro-
amp DC current will flow through the flame between the
sensor electrode and the grounded burner.
7. When the controller proves that the flame has been
established, it will keep the gas valve energized and
discontinue the ignition spark. First stage manifold
pressure will be approximately 2.0" w.c. for natural gas
and 7.0" w.c. for propane (LP).
8. Ifthecontrolisunableto ignitetheburnersafteritsinitial
attempt,itwillinitiateanotherpurgeandsparksequence.
A third purge and spark sequence will be initiated if the
second attempt is unsuccessful. If the third attempt is
unsuccessful, the controller will close the gas valve and
lockitselfout.Itmayberesetbymomentarilyinterrupting
power. This may be accomplished by briefly lowering the
room thermostat set-point below room temperature, or
by shutting off the main power to the unit. (See TP-105
for more details.)
9. Integrated ignition control will close its normally open
contacts after a delay of approximately 30 seconds. This
action energizes contactor BC and starts the supply fan
motor. Operation of the supply fan circulates air across
the heat exchanger and delivers heated air to the
conditioned space.
10. When the space temperature rises, the thermostat will
open R-W. Opening R-W will cause the gas valve to close,
and the furnace to shut down.
11. The furnace has three high temperature limit controls,
which can shut down the burner. They do not shut down
the ventor motor.
Unit Shutdown
1. Set the thermostat to lowest setting.
2. Turn off the electrical power supply to the unit.
3. Remove the heat exchanger door on the side of the unit
by removing screws.
4. Movethe gas controlvalveswitchto theOFF position.Do
not force.
5. Close manual gas shut off valve external to the unit.
6. Replace the heat exchanger door on the unit.
7. If cooling and/or air circulation will be desired, turn ON
the electrical power.
AUTOMATIC RESET HIGH LIMIT CONTROL (LS)
Locatedintheburnercompartmentontheheatexchanger,itssens-
ing element projects through the blower section bulkhead and
sensesthe temperatureattherearofthefurnace. It will cycle the
furnace off if the temperature exceeds 100°F plus maximum rise.
AUXILIARY RESET HIGH LIMIT CONTROL (ALS)
Located in the blower compartment on the blower housing, it
senses air temperature within the blower compartment and pro-
tects the filters from excessive temperature. It will shut down the
furnace if it senses excessive temperatures.
Elevated temperatures at the control are normally caused by
blower failure. The reason for the opening should be determined
and repaired prior to resetting.