COMFORT-AIRE GUH97M Installation Instructions Manual
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COMFORT-AIRE GUH97M Installation Instructions Manual

Warm air gas furnace
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This is a safety alert symbol and should never be ignored. When you see this symbol on labels or in
manuals, be alert to the potential for personal injury or death.
As with any mechanical equipment, personal injury can
result from contact with sharp sheet metal edges. Be
careful when you handle this equipment.
Improper installation, adjustment, alteration, service
or maintenance can cause property damage, personal
injury or loss of life. Installation and service must be
performed by a licensed professional installer (or
equivalent), service agency or the gas supplier.
Unit Dimensions ..........................................................2
Parts Arrangement.......................................................3
A97USMV Gas Furnace ..............................................4
Shipping and Packing List ...........................................4
Safety Information .......................................................4
General ........................................................................6
Installation - Setting Equipment ..................................6
Filters .........................................................................10
Duct System ..............................................................11
Venting Practices .......................................................13
*P507028-03*
(P) 507028-03
507028-03
INSTALLATION INSTRUCTIONS
Warm Air Gas Furnace
Upflow/Horizontal Left and
Right Air Discharge
This manual must be left with the homeowner for future reference.
CAUTION
WARNING

Table of Contents

GUH97M
A thermostat is not included.
In non-communicating applications, a traditional
non-communication thermostat may be used.
In all cases, setup is critical to ensure proper system
operation.
Field
wiring
is illustrated in these instructions.
Gas Piping .................................................................27
Electrical ....................................................................30
Blower Performance ..................................................44
Unit Start-Up ..............................................................52
High Altitude Information ...........................................54
Other Unit Adjustments..............................................55
Heating Sequence of Operation ................................55
Service.......................................................................57
Integrated Control Diagnostic Codes.........................59
Repair Parts List ........................................................61
Issue 1809
NOTICE
for
non-communicating applications
Manufactured By
Comfort-Aire / Century
1900 Wellworth Ave.
Jackson, MI 49203
Page 1 of 66

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  • Page 1: Table Of Contents

    Heating Sequence of Operation ........55 Filters .................10 Service...............57 Duct System ..............11 Integrated Control Diagnostic Codes......59 Venting Practices ............13 Repair Parts List ............61 Manufactured By Comfort-Aire / Century *P507028-03* 1900 Wellworth Ave. Jackson, MI 49203 (P) 507028-03 507028-03 Issue 1809 Page 1 of 66...

  • Page 2: Unit Dimensions

    Unit Dimensions * NOTE - C/D20 size units that require second stage air volumes over 1800 cfm (850 L/S) must have one of the following: • Single side return air with transition, to accommodate 20 x 25 x 1 in. (508 x 635 x 25 mm) air filter. •...

  • Page 3: Parts Arrangement

    Parts Arrangement Figure 1. 507028-03 Issue 1809 Page 3 of 66...

  • Page 4: Shipping And Packing List

    GUH97M Gas Furnace Safety Information The GUH97M Category IV gas furnace is equipped with a variable capacity, variable speed integrated control. Each GUH97M is shipped ready for installation in the upflow, DANGER horizontal left air discharge or horizontal right air DANGER OF EXPLOSION! discharge position.
  • Page 5 HEAT or COOL setting. See Figure 3. The GUH97M furnace may be installed in alcoves, Heating Unit Installed Parallel to Air Handler Unit closets, attics, basements, garages, crawl spaces and utility rooms.

  • Page 6: General

    Figure 4. when installing one of these furnaces: GUH97M applications which include side return air and a • Place the furnace as close to the center of the air condensate trap installed on the same side of the cabinet distribution system as possible.
  • Page 7 UNIT MUST BE LEVEL SIDE TO SIDE IN ALL APPLICATIONS FOR PROPER OPERATION. A SLIGHT TILT TOWARD THE DRAIN IS RECOMMENDED FOR PROPER DRAINAGE. 1/2" Max 1/2" Max TILT THE UNIT SLIGHTLY (MAX. 1/2”) FROM BACK TO FRONT TO AID IN THE DRAINING OF THE HEAT EXCHANGER.
  • Page 8 CONDENSATE TRAP FURNACE FRONT 23 (584) 3−1/4 IF BASE Overall (83) IS USED (Maximum) Minimum WITHOUT 11 (279) IAQ CABINET, Maximum 22−7/16 A SINGLE Unit side return air 14 (356) (570) INDOOR AIR RETURN AIR Opening Overall QUALITY PLENUM (Maximum) MUST CABINET AIR FLOW...
  • Page 9 Fire, explosion, carbon monoxide poisoning, personal injury and/or property Horizontal Applications damage could result. The GUH97M furnace can be installed in horizontal applications with either right or left hand air discharge. Refer to Figure 11 for clearances in horizontal applications. Right-Hand Discharge Top/Plenum 1 in.

  • Page 10: Filters

    Suspended Installation of Horizontal Unit This furnace may be installed in either an attic or a crawlspace. Either suspend the furnace from roof rafters or floor joists, as shown in Figure 12 or install the furnace on a platform, as shown in Figure 13. A horizontal suspension kit (51W10) may be ordered or use equivalent.

  • Page 11: Duct System

    Duct System Piping and Fittings Specifications Use industry approved standards to size and install the Schedule 40 PVC (Pipe) D1785 supply and return air duct system. This will result in a quiet and low static system that has uniform air distribution. Schedule 40 PVC (Cellular Core Pipe) F891 NOTE: Operation of this furnace in heating mode (indoor...
  • Page 12 Joint Cementing Procedure All cementing of joints should be done according to the CAUTION specifications outlined in ASTM D2855. Solvent cements for plastic pipe are flammable liquids and should be kept away from all sources of ignition. Do not use excessive amounts of solvent cement when DANGER making joints.

  • Page 13: Venting Practices

    Outdoor Exhaust Exhaust Flush 1-1/2” 2” 3” Accelerator VENT Accelerator Mount Concentric Concentric Concentric (Dia. X PIPE (Dia. X GUH97M Length) DIA. Length) (in.) 71M80 69M29 60L46 1-1/2” X 12” 2” X 12” 51W11 * or 44W93+ +44W92++ +44W92++ 2-1/2 2-1/2 2-1/2 * Kit 51W11 is provided with a 1-1/2”...
  • Page 14 Vent Piping Guidelines Min. Equiv. Model Example This unit is installed only as a Direct Vent gas central Vent Length furnace. 5ft. plus 2 elbows of 2”, 2-1/2”, 070, 090 or 3” diameter pipe NOTE: In Direct Vent installations, combustion air is taken from outdoors and flue gases are discharged outdoors.
  • Page 15 General Guidelines for Vent Terminations In Direct Vent applications, combustion air is taken from IMPORTANT outdoors and the flue gases are discharged to the outdoors. This gas furnace is classified as a direct vent, Category IV Do not use screens or perforated metal in exhaust gas furnace.
  • Page 16 Figure 19. Typical Exhaust Pipe Connections and Condensate Trap Installation in Horizontal Air Applications (Right Hand Discharge Shown) Maximum Allowable Vent Pipe Length without Insulation in Unconditioned Space for Winter Design Temperatures Modulating High Efficiency Furnace Vent Pipe Winter Design Temperatures ºF (ºC) Diameter...
  • Page 17 Maximum Allowable Intake or Exhaust Vent Length (feet) Standard Termination at Elevation 0 - 4,500 ft 2” Pipe 2-1/2” Pipe 3” Pipe Number of 90° Elbows Modal Model Model Used Standard Termination at Elevation 4,501 - 10,000 ft 2” Pipe 2-1/2”...
  • Page 18 Maximum Allowable Intake or Exhaust Vent Length (feet) Concentric Termination at Elevation 0 - 4,500 ft 2" Pipe 2-1/2" Pipe 3" Pipe Number of 90° Elbows Model Model Model Used Concentric Termination Elevation 4,501 - 10,000 ft 2" Pipe 2-1/2" Pipe 3"...
  • Page 19 VENT TERMINATION CLEARANCES FOR DIRECT VENT INSTALLATIONS IN THE USA AND CANADA INSIDE CORNER DETAIL Fixed Operable Fixed Closed Closed Operable AREA WHERE TERMINAL AIR SUPPLY INLET VENT TERMINAL IS NOT PERMITTED US Installations Canadian Installations Clearance above grade, veranda, 12 inches (305mm) or 12 in.
  • Page 20 FIELD FABRICATED WALL TERMINATION NOTE − FIELD−PROVIDED REDUCER MAY BE 2” (51mm) 3” (76mm) REQUIRED TO ADAPT LARGER VENT PIPE SIZE Vent Pipe Vent Pipe TO TERMINATION A− Minimum clearance above grade or average 12” (305 mm) 12” (305 mm) snow accumulation B−...
  • Page 21 Details of Intake and Exhaust Piping Terminations for Direct Vent Installations NOTE: In Direct Vent installations, combustion air is taken from outdoors and flue gases are discharged to outdoors. NOTE: Flue gas may be slightly acidic and may adversely affect some building materials. If any vent termination is Inlet Air Minimum 12 in.
  • Page 22 (610 mm) as shown in Figure 21. Exhaust and 2” EXTENSION FOR 2” PVC PIPE intake piping that is run up a wall is considered to 1” EXTENSION FOR 3” PVC PIPE be in an unconditioned space, so piping should be sized according to Table 5.
  • Page 23 Exhaust through Crawl Space Vent Option All 33” condensing gas furnaces (92%+) are now approved Exhaust from to be vented down through a crawl space. Ensure a vent Furnace pipe drain kit, 51W18 (USA) or 15Z70 (Canada), is used as To Termination directed through the floor joists and into the crawl space.
  • Page 24 Condensate Piping flooded heat exchanger if the combined primary drain line were to become restricted. This unit is designed for either right or left side exit of condensate piping in upflow applications. In horizontal Horizontal furnace (Figure 36 or Figure 39) - In applications, the condensate trap must extend below the horizontal furnace applications, the field provided vent unit.
  • Page 25 TRAP / DRAIN ASSEMBLY USING 1/2” PVC OR 3/4” PVC    °                     °  °    ...
  • Page 26 Figure 36. GUH97M with Evaporator Coil Using a Separate Drain (Unit shown in horizontal Left hand discharge position) Figure 38. Evaporator Coil Using a Common Drain Figure 37. Evaporator Coil Using A Separate Drain IMPORTANT When combining the furnace and evaporator coil...

  • Page 27: Gas Piping

    Piping should be sloped 1/4 “ per 15 feet (6 mm per 5.6 m) upward toward the gas meter from the furnace. The piping must be supported at proper intervals, every 8 to 10 feet (2.44 to 3.05 m), using suitable hangers or straps.
  • Page 28 NOTE: BLACK IRON PIPE ONLY TO BE ROUTED INSIDE OF CABINET Figure 42. Upflow Applications Possible Gas Piping Configurations NOTE: BLACK IRON PIPE ONLY TO BE ROUTED INSIDE OF CABINET Figure 43. Horizontal Applications Possible Gas Piping Configurations Page 28 of 66 Issue 1809 507028-03...
  • Page 29 Gas Pipe Capacity - FT³/HR (kL/HR) Nominal Length or Pipe - feet (m) Internal Iron Pipe Diameter Size - - inches inches (3.048) (6.096) (9.144) (12.192) (15.240) (18.288) (21.336) (24.384) (27.432) (30.480) (mm) (mm) .622 (12.7) (17.799) (4.96) (3.40) (2.75) (2.32) (2.07) (1.87)

  • Page 30: Electrical

    common venting system. Turn ON any exhaust fans, Electrical such as range hoods and bathroom exhausts, so they will operate at maximum speed. Do not operate a ELECTROSTATIC DISCHARGE (ESD) summer exhaust fan. Close fireplace dampers. Precautions and Procedures Follow the lighting instructions. Turn ON the appliance that is being inspected.
  • Page 31 Wire Run Length AWG# Insulation / Core Types Maximum Over Current Less than 100’ Color coded, temperature GUH97M Model Protection (Amps) (30 m) rating 95° F (35° C) minimum, solid core. (Class II Rated 070B3, 090C3, 090C4 More than 100’...
  • Page 32 Switches 4 and 5 - Blower Off Delay - The blower On • The furnace operates at 60 Hz ± 5% (Range: 57 Hz to 63 Hz). delay of 30 seconds is not adjustable. The blower Off delay (time that the blower operates after the heating demand •...
  • Page 33 • Once demand is met, motor runs at 50% for 30 Speed Switch 8 Switch 9 seconds then ramps down to stop. 1 - Low 2 - Medium Low 3 - Medium High 4 - High (Factory) Table 13. Cooling Mode Blower Speeds Ramping Option “B”...
  • Page 34 Error Code Recall Mode - Select “E” from the menu to DIP Switch Settings Blower Thermostat access the most recent 10 error codes. Select “c” from the Speed Demand Error Code Recall menu to clear all error codes. Button Adjustments must be pressed a second time while “c”...
  • Page 35 Figure 47. Typical GUH97M Field Wiring Diagram for Standard Non-Communicating Thermostat 507028-03 Issue 1809 Page 35 of 66...
  • Page 36 Field Wiring Connections for Non-Communicating Thermostat Applications D IP S w itc h S e ttin g s a n d O n -B o a rd L in k s (fig u re N O T A G ) D IP S w itc h 1 W 9 1 5 W 9 1 4...
  • Page 37 Field Wiring for Non-Communicating Applications (continued) D IP S w itch S ettin g s an d O n -B o ard L in ks (fig u re N O T AG ) D IP S w itch 1 W 915 W 914 W 951 (Y 1 to Y 2)
  • Page 38 * Connect W1 to W1 ONLY if using defrost tempering kit 67M41. NOTE: Do NOT make a wire connection between the room thermolstat L terminal and the L terminal of the GUH97M integrated control. Table 19. Field Wiring Connections for Non-Communicating Thermostat Applications with Dual Fuel Capability...
  • Page 39 Single Stage 2 Stage DIP Switch Settings & On Board Links DIP Switch Settings & On Board Links W915 W914 W915 W914 W951 W951 Thermostat Thermostat (Y1 to Y2) (DS to R) (Y1 to Y2) (DS to R) (O to R) (O to R) Switch Two Stage...
  • Page 40 Figure 50. Typical GUH97M Wiring Diagram Page 40 of 66 Issue 1809 507028-03...
  • Page 41 Integrated Control NEUTRAL TERMINALS COMBUSTION AIR INDUCER CONNECTOR IGNITOR FLAME CONNECTOR SENSE DIAGNOSTIC LINE VOLTAGE PUSH BUTTON TERMINALS DIP SWITCHES OUTDOOR AIR INDOOR SENSOR BLOWER TERMINALS 7-SEGMENT CONNECTOR DIAGNOSTIC LED W915 Y1 TO Y2 DISCHARGE AIR SENSOR W951 R TO O TERMINALS W914 R TO DS FACTORY TEST...

  • Page 42: Blower Performance

    Blower Performance GUH97M070B3M BLOWER PERFORMANCE (less filter) HEATING BLOWER PERFORMANCE BOTTOM RETURN AIR Heating Input Range and Blower Volume - CFM Heating Adjust CFM Selections 100%. Increase (+15%) Heat CFM 1030 1128 Increase (+7.5%) Heat CFM 1048 Default Heat CFM Decrease (-7.5% ) Heat CFM Decrease (-15% ) Heat CFM COOLING BLOWER PERFORMANCE...
  • Page 43 GUH97M070B3M BLOWER PERFORMANCE (less filter) RIGHT SIDE RETURN AIR WITH OPTIONAL RETURN AIR BASE HEATING BLOWER PERFORMANCE Heating Input Range and Blower Volume - CFM Heating Adjust CFM Selections 100% Increase (+15%) Heat CMS 1091 Increase (-7.5%) Heat CFM 1021 Default Heat CFM Decrease (-7.5% ) Heat CFM Decrease (-15% ) Heat CFM...
  • Page 44 GUH97M090C3M BLOWER PERFORMANCE (less filter) RIGHT SIDE RETURN AIR HEATING BLOWER PERFORMANCE Heating Input Range and Blower Volume- CFM Heating Adjust CFM Selections 100% Increase (+15%) Heat CFM 1061 1150 1240 Increase (+7.5%) Heat CFM 1010 1094 1178 Default Heat CFM 1037 1116 Decrease (-7.5% ) Heat CFM...
  • Page 45 GUH97M090C4M BLOWER PERFORMANCE (less filter) BOTTOM RETURN AIR HEATING BLOWER PERFORMANCE Heating Input Range and Blower Volume- CFM Heating Adjust CFM Selections 100% Increase (+15%) Heat CFM 1101 1234 1367 1500 1633 Increase (+7.5%) Heat CFM 1028 1155 1281 1407 1534 Default Heat CFM 1075...
  • Page 46 GUH97M090C4M BLOWER PERFORMANCE (less filter) RIGHT SIDE RETURN AIR WITH OPTIONAL RETURN AIR BASE HEATING BLOWER PERFORMANCE Heating input Range and Blower Volume - CFM Heating Adjust CFM Selections 100% Increase (+15%) Heat CFM 1084 1213 1341 1469 1597 Increase (+7.5%) Heat CFM 1010 1132 1255...
  • Page 47 GUH97M090C5M BLOWER PERFORMANCE (less filter) RIGHT SIDE RETURN AIR HEATING BLOWER PERFORMANCE Heating input Range and Blower Volume - CFM Heating Adjust CFM Selections 100% Increase (+15%) Heat CFM 1136 1287 1437 1588 Increase (+7.5%) Heat CFM 1059 1205 1350 1496 Default Heat CFM 1123...
  • Page 48 GUH97M110C5M BLOWER PERFORMANCE (less filter) BOTTOM RETURN AIR HEATING BLOWER PERFORMANCE Heating Input Range and Blower Volume - CFM Heating Adjust CFM Selections 100% Increase (+15%) Heat CFM 1049 1237 1424 1612 1800 1988 Increase (+7.5%) Heat CFM 1000 1174 1349 1524 1699...
  • Page 49 GUH97M110C5M BLOWER PERFORMANCE (less filter) RIGHT SIDE RETURN AIR WITH OPTIONAL RETURN AIR BASE HEATING BLOWER PERFORMANCE Heating Input Range and Blower Volume - CFM Heating Adjust CFM Selections 100% Increase (+15%) Heat CFM 1068 1243 1419 1594 1770 1945 Increase (+7.5%) Heat CFM 1157 1329...

  • Page 50: Unit Start-Up

    Wait for the combustion air inducer to stop. Set the Unit Start-Up thermostat to initiate a heating demand and again allow the burners to fire for approximately 3 minutes. FOR YOUR SAFETY READ BEFORE OPERATING Adjust the thermostat to deactivate the heating demand and again wait for the combustion air inducer to stop.
  • Page 51 Gas Pressure Measurement Gas Flow (Approximate) Seconds for One Revolution GUH97M Natural Unit 1 cu ft 2 cu ft 1 cu ft 2 cu ft Dial Dial Dial Dial -110 -135 Natural - 1000 btu/cu ft LP - 2500 btu/cu ft Figure 52.

  • Page 52: High Altitude Information

    The maximum carbon monoxide reading should not exceed 100 ppm. Tee into the negative line between the gas valve and pressure switch and connect to measuring device GUH97M Unit % for Nat % for L.P. negative “-”.

  • Page 53: Other Unit Adjustments

    Are pressure switches closed? Obstructed exhaust GUH97M Unit % for Nat % for L.P. pipe will cause unit to shut off at pressure switches. 7.2 - 8.2 Check termination for blockages. Reset manual flame rollout switches on burner box 5.3 - 6.3 6.8 - 7.8...
  • Page 54 inducer at high speed. The control also checks the is adjusted to a speed appropriate for the target rate. high fire pressure switch to make sure it is closed. If second-stage heat demand is satisfied, but first stage As the inducer speed is increased to high, the indoor is still present, the furnace will continue to operate at blower motor is adjusted to a speed appropriate for the the present firing rate until the heat cycle ends.

  • Page 55: Service

    When the combustion air post-purge period is Check for the correct voltage at the furnace (furnace complete, the inducer is de-energized. The indoor operating). blower is de-energized at the end of the OFF delay. Check amp-draw on the blower motor. Motor Nameplate_____________ Actual___________ Service Winterizing and Condensate Trap Care...
  • Page 56 compartment components. Disengage strain relief 36. Secure burner box assembly to vestibule panel using bushing and pull wiring and bushing through the hole four existing screws. Make sure burners line up in in the blower deck. center of burner ports. 16.

  • Page 57: Integrated Control Diagnostic Codes

    Planned Service Integrated Control Diagnostic Codes A service technician should check the following items during an annual inspection. Power to the unit must be Press the diagnostic push button and hold it to cycle shut off for the service technician’s safety. through a menu of options.
  • Page 58 Integrated Control and Diagnostic Codes Flash Code Diagnostics Codes / Status of Furnace Idle Mode (Decimal blinks at 1 Hz 0.5 sec. On and 0.5 sec. Off) CFM Displayed (1 sec. On, 0.5 sec. Off, CFM value) Staged Cooling (1 sec. On, 0.5 sec. Off 1 or 2 stage 1 sec. pause, CFM, pause, Repeat Codes) Dehumidification Mode (1 sec.

  • Page 59: Repair Parts List

    Repair Parts List The following repair parts are available through Comfort-Aire/Century distributors. When ordering parts, include the complete furnace model number listed on the nameplate. All service must be performed by a licensed professional installer (or equivalent), service agency, or gas supplier.
  • Page 60 Program Unit Capacity / Size Mode Power-Up - Number displayed by integrated control represents unit size code (furnace model and capacity). If three horizontal bars are displayed followed by continuous E203, furnace control does not recognize unit size code. Configure per the following: Turn room thermostat to OFF.
  • Page 61 Troubleshooting: Heating Sequence of Operation Ignition and Call for Low Fire With Two Stage Thermostat Safety Check Verify There Is No Main Burner Flame After Indoor blower OFF Heat OFF Delay (Low Heat Speed) Combustion Air Limit Limit De-Energize Error Code Indoor Blower Switch Inducer On...
  • Page 62 Troubleshooting : Heating Sequence of Operation (continued) Call for High Fire with Two Stage Thermostat 2 Stage Thermostat 1st Call for High Fire? 2nd Stage Recognition Delay (30 Seconds) Combustion Air Inducer ON (100% Rate Speed) High Pressure Switch Increase Combustion Error Code Wait 5 Closes Within...
  • Page 63 Troubleshooting : Heating Sequence of Operation (continued) Call for Heat Satisfied RUN MODE (TWO-STAGE THERMOSTAT) RUN MODE (SINGLE-STAGE THERMOSTAT) FIRST OR SECOND-STAGE CALL FOR HEAT ALL INPUTS MONITORED (LIMIT, PRESSURE, ALL INPUTS MONITORED (LIMIT, PRESSURE, CALL FOR HEAT/COOL, FLAME LEVEL). CALL FOR HEAT/COOL, FLAME LEVEL).
  • Page 64 Troubleshooting : Cooling Sequence of Operation CALL FOR COOLING 1st Stage Cooling Request Received Energize 1st Stage Cooling Contactor (Compressor & Fan) Indoor Blower On After 2-second delay Energize Indoor Blower (Per Ramping Profile) 1st Stage 2nd Stage Cooling Request Cooling Still Active? Request?
  • Page 65 Troubleshooting : Continuous Fan Sequence of Operation Continuous Low Speed Indoor Blower Sequence of Operation Call for Continuous Blower Indoor Blower On (Speed Determined by Dip Switch settings) Request Maintain Indoor for Cooling Go to Call for Cooling Blower at set speed Received? Go to Call for Heat -- Two-Stage Thermostat Request...
  • Page 66 Requirements for Commonwealth of Massachusetts Modifications to NFPA-54, Chapter 10 INSPECTION. The state or local gas inspector of the side wall, horizontally vented, gas-fueled equipment Revise NFPA-54 section 10.8.3 to add the following shall not approve the installation unless, upon requirements: inspection, the inspector observes carbon monoxide For all side wall, horizontally vented, gas-fueled equipment...

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