COMFORT-AIRE GUH95A Installation Instructions Manual
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COMFORT-AIRE GUH95A Installation Instructions Manual

COMFORT-AIRE GUH95A Installation Instructions Manual

Warm air gas furnace
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Upflow/Horizontal Left and Right Air Discharge
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.
Unit Dimensions ..........................................................2
Parts Arrangement.......................................................3
Gas Furnace ................................................................4
Shipping and Packing List ...........................................4
Safety Information .......................................................4
General ........................................................................6
Combustion, Dilution & Ventilation Air .........................7
Installation .................................................................10
Filters .........................................................................13
Duct System ..............................................................13
Venting Practices .......................................................16
Condensate Piping ....................................................36
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.
Manufactured By
Comfort-Aire / Century
1900 Wellworth Ave.
Jackson, MI 49203
507715-01
INSTALLATION INSTRUCTIONS
GUH95A & GUH92A
Warm Air Gas Furnace
This manual must be left with the homeowner for future reference.

Table of Contents

WARNING
Save these instructions for future reference
Gas Piping .................................................................39
Electrical ....................................................................42
Unit Start-Up ..............................................................45
Air for Non-Direct Vent Applications ..........................49
Other Unit Adjustments..............................................50
Blower Performance GUH92A ...................................51
Blower Performance GUH95A ...................................54
Service.......................................................................56
Planned Service ........................................................58
Repair Parts List ........................................................58
Start-Up & Performance Checklist.............................59
As with any mechanical equipment, personal injury can
result from contact with sharp sheet metal edges. Be
careful when you handle this equipment.
Issue 1716
CAUTION
*P507715-01*
(P) 507715-01
Page 1 of 61

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Summary of Contents for COMFORT-AIRE GUH95A

  • Page 1: Table Of Contents

    Air for Non-Direct Vent Applications ......49 General ................6 Other Unit Adjustments..........50 Combustion, Dilution & Ventilation Air ......7 Blower Performance GUH92A ........51 Installation ..............10 Blower Performance GUH95A ........54 Filters .................13 Service...............56 Duct System ..............13 Planned Service ............58 Venting Practices ............16 Repair Parts List ............58 Condensate Piping ............36...

  • Page 2: Unit Dimensions

    2 Optional External Side Return Air Filter kit is not for use with optional Return Air Base. * Consider sizing requirements for optional IAQ equipment before cutting side return opening. FRONT VIEW SIDE VIEW GUH95A / GUH92A Capacity 045-2 045-3 17-1/2 16-3/8...

  • Page 3: Parts Arrangement

    Parts Arrangement Figure 1. 507715-01 Issue 1716 Page 3 of 61...

  • Page 4: Gas Furnace

    1 - Snap Plug return air. 1 - Wire tie The GUH95A & GUH92A can be installed as either a Direct 1 - Condensate trap Vent or a Non-Direct Vent gas central furnace 1 - Condensate trap cap...
  • Page 5 GUH95A & GUH92A units are CSA International certified is manually operated, it must be equipped to prevent to ANSI Z21.47 and CSA 2.3 standards. operation of either the heating or the cooling unit, unless it is in the full HEAT or COOL setting.

  • Page 6: General

    Use of Furnace as a Construction Heater General WARNING These instructions are intended as a general guide and do not supersede local codes in any way. Consult authorities Gas furnaces manufactured on or after May 1, 2017, having jurisdiction before installation. are not permitted to be used in Canada for heating of buildings or structures under construction.

  • Page 7: Combustion, Dilution & Ventilation Air

    of this information has been reprinted with permission from Combustion, Dilution & Ventilation Air the National Fuel Gas Code (ANSI-Z223.1/NFPA 54). This reprinted material is not the complete and official position If this unit is installed as a Non-Direct Vent Furnace, follow of ANSI on the referenced subject, which is represented the guidelines in this section.
  • Page 8 When the furnace is installed so that supply ducts carry air circulated by the furnace to areas outside the space containing the furnace, the return air must be handled by ducts which are sealed to the furnace casing and which terminate outside the space containing the furnace.
  • Page 9 Ventilation Louvers Inlet Air Roof Terminated (Minimum 12 in. Exhaust Pipe (305mm) above Attic Floor) *Intake Debris Screen (Provided) Furnace * See Maximum Vent Lengths table NOTE: The inlet and outlet air openings shall each have a free area of at least one square inch per 4,000 Btu (645 mm 1.17 kW) per hour of the total input rating of all equipment in the enclosure.

  • Page 10: Installation

    Allow for clearances to combustible materials as indicated Installation on the unit nameplate. Setting Equipment WARNING Improper installation of the furnace can result in WARNING personal injury or death. Combustion and flue products Do not connect the return air ducts to the back of the must never be allowed to enter the return air system or furnace.
  • Page 11 Markings are provided on both sides of the furnace cabinet for installations that require side return air. Cut the furnace cabinet at the maximum dimensions shown on Page 2. Furnace applications which include side return air and a condensate trap installed on the same side of the cabinet (trap can be installed remotely within 5 ft.) require either a return air base or field-fabricated transition to accommodate an optional IAQ accessory taller than 14.5”.
  • Page 12 Removing the Bottom Panel Remove the two screws that secure the bottom cap to the furnace. Pivot the bottom cap down to release the bottom panel. Once the bottom panel has been removed, reinstall the bottom cap. See Figure 16. Top/Plenum 1 in.

  • Page 13: Filters

    NOTE: Heavy-gauge sheet metal straps may be used to Filters suspend the unit from roof rafters or ceiling joists. When straps are used to suspend the unit in this way, support must be provided for both the ends. The straps must not This unit is not equipped with a filter or rack.
  • Page 14 SPECIFICATION PVC & CPVC Primer F656 IMPORTANT PVC Solvent Cement D2564 GUH95A & GUH92A exhaust and intake connections CPVC Solvent Cement F493 are made of PVC. Use PVC primer and solvent cement ABS Solvent Cement D2235 when using PVC vent pipe. When using ABS vent pipe,...
  • Page 15 STANDARD CONCENTRIC Outdoor Outdoor Exhaust 1-1/2” 2” 3” Exhaust Flush Accelerator Concentric Concentric Concentric VENT Accelerator Mount Kit Capacity PIPE DIA. (Dia. X Length) (Dia. X Length) (in.) 71M80 69M29 60L46 1-1/2” X 12” 2” X 12” 51W11 ** or 44W93+ +44W92++ +44W92++ 2-1/2...

  • Page 16: Venting Practices

    Seal any unused openings in the common venting Venting Practices system. Inspect the venting system for proper size and horizontal pitch. Determine that there is no blockage, restriction, leakage, corrosion, or other deficiencies which could cause an unsafe condition. Close all building doors and windows and all doors between the space in which the appliances remaining connected to the common venting system are located and other spaces of the building.
  • Page 17 Refer to Table 8. In some applications which permit the use of several different sizes of vent pipe, a combination vent pipe may be used. Contact Comfort-Aire / Century for assistance in sizing vent pipe in these applications. 507715-01...
  • Page 18 Use Figure 24 to correctly size vent pipe diameter. 045, 070, Furnace capacity? 090, 110 Standard or Which termination? Concentric? See Table 3 Which needs most Intake or elbows? Exhaust? How many? 2”, 2-1/2” Desired pipe size? or 3” What is the altitude? Use Table 5 or Table 6 to find max pipe length.
  • Page 19 GUH92A Maximum Allowable Intake or Exhaust Vent Length in Feet Standard Termination at Elevation 0 - 10,000 ft 2" Pipe 2-1/2" Pipe 3" Pipe Number of 90° Elbows Capacity Capacity Capacity Used Concentric Termination Elevation 0 - 10,000 ft 2" Pipe 2-1/2"...
  • Page 20 GUH92A Maximum Allowable Exhaust Vent Length with Furnace Installed in a Closet or Basement Using Ventilated Attic or Crawl Space for Intake in Feet Standard Termination at Elevation 0 - 10,000 ft 2" Pipe 2-1/2" Pipe 3" Pipe Number of 90°...
  • Page 21 GUH95A Maximum Allowable Intake or Exhaust Vent Length in Feet Standard Termination at Elevation 0 - 4,500 ft 2" Pipe 2-1/2" Pipe 3" Pipe Number of 90° Elbows Capacity Capacity Capacity Used Standard Termination Elevation 4,501 - 10,000 ft 2" Pipe 2-1/2"...
  • Page 22 GUH95A Maximum Allowable Intake or Exhaust Vent Length in Feet Concentric Termination at Elevation 0 - 4,500 ft 2" Pipe 2-1/2" Pipe 3" Pipe Number of 90° Elbows Capacity Capacity Capacity Used Concentric Termination Elevation 4,501 - 10,000 ft 2" Pipe 2-1/2"...
  • Page 23 GUH95A Maximum Allowable Exhaust Vent Length with Furnace Installed in a Closet or Basement Using Ventilated Attic or Crawl Space for Intake in Feet Standard Termination at Elevation 0 - 4,500 ft 2" Pipe 2-1/2" Pipe 3" Pipe Number of 90°...
  • Page 24 Figure 25. Figure 26. Page 24 of 61 Issue 1716 507715-01...
  • Page 25 Figure 27. Figure 28. Intake Piping See Figure 27 through Figure 30 This gas furnace may be installed in either direct vent or non-direct vent applications. In non-direct vent applications, when intake air will be drawn into the furnace from the surrounding space, the indoor air quality must be considered and guidelines listed in Combustion, Dilution and Ventilation Air section must be followed.
  • Page 26 Figure 30. The air intake piping must not terminate too close to the flooring or a platform. Ensure that the intake air inlet will not be obstructed by loose insulation or other items that may clog the debris screen. Figure 29. If intake air is drawn from a ventilated attic (Figure 31) or ventilated crawlspace (Figure 32) the exhaust vent length must not exceed those listed in Table 5B...
  • Page 27 General Guidelines for Vent Terminations In Non–Direct Vent applications, combustion air is taken Roof Terminated from indoors and the flue gases are discharged to the Exhaust Pipe outdoors. This furnace is then classified as a non–direct vent, Category IV gas furnace. In Direct Vent applications, combustion air is taken from Inlet Air outdoors and the flue gases are discharged to the outdoors.
  • Page 28 ‡ Permitted only if veranda, porch, deck or balcony is fully open on a minimum of two sides beneath the floor. Comfort-Aire / Century recommends avoiding this location if possible. Figure 34. Vent Termination Clearances for Non-Direct Vent Installations...
  • Page 29 ‡ Permitted only if veranda, porch, deck or balcony is fully open on a minimum of two sides beneath the floor. Comfort-Aire / Century recommends avoiding this location if possible. Figure 35. Vent Termination Clearances for Direct Vent Installations...
  • Page 30 Details of Intake and Exhaust Piping In both Non–Direct Vent and Direct Vent applications, the vent termination is limited by local building codes. In the Terminations for Direct Vent Installations absence of local codes, refer to the current National Fuel NOTE: In Direct Vent installations, combustion air is taken Gas Code ANSI Z223-1/NFPA 54 in U.S.A., and current from outdoors and flue gases are discharged to outdoors.
  • Page 31 the intake pipe without a termination elbow is 8” and a 3”(76MM) MAX. SIZE PER EXHAUST PIPE Inches (MM) minimum distance of 6” with a termination elbow. See TERMINATION SIZE Figure 44. REDUCTION TABLE If intake and exhaust piping must be run up a side UNCONDITIONED ATTIC SPACE wall to position above snow accumulation or other...
  • Page 32 FIELD-PROVIDED STRAIGHT-CUT OR ANGLE-CUT IN DIRECTION REDUCER MAY BE REQUIRED 3”-8” 1-1/2” (38mm) accelerator OF ROOF SLOPE TO ADAPT LARGER VENT (76MM-203MM) provided on 71M80 & 44W92 PIPE SIZE TO TERMINATION kits for -45 and -70 units OUTSIDE 8” - 12” INTAKE WALL (203MM - 305MM)
  • Page 33 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 34 Details of Exhaust Piping Terminations for Non- Direct Vent Applications Exhaust pipes may be routed either horizontally through an outside wall or vertically through the roof. In attic or closet installations, vertical termination through the roof SIZE TERMINATION PER EXHAUST PIPE is preferred.
  • Page 35 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. The following Furnace diagrams show the approved methods. Ensure a sanitary To Termination tee is used as directed for condensate control. Consult the vent tables for vent lengths and approved materials.

  • Page 36: Condensate Piping

    Install drain trap using appropriate PVC fittings, glue Condensate Piping all joints. Glue the provided drain trap as shown in Figure 58. Route the condensate line to an open drain. This unit is designed for either right or left side exit of Condensate line must maintain a 1/4”...
  • Page 37 * Piping from furnace must slope down a minimum of 1/4” per ft. toward trap. Figure 54. Evaporator Coil Using a Separate Drain (Unit shown in horizontal right-hand discharge position) Figure 55. Evaporator Coil Using a Separate Drain Figure 56. Evaporator Coil Using a Common Drain * Piping from furnace must slope down a minimum of 1/4”...
  • Page 38 Figure 58. Trap / Drain Assembly Using 1/2” PVC or 3/4” PVC Page 38 of 61 Issue 1716 507715-01...

  • Page 39: Gas Piping

    When connecting gas supply, factors such as length of run, number of fittings and furnace rating must be considered to avoid excessive pressure drop. Table 9 list recommended pipe sizes for typical applications. NOTE: Use two wrenches when connecting gas piping to avoid transferring to the manifold.
  • Page 40 IMPORTANT WARNING FIRE OR EXPLOSION HAZARD When testing pressure of gas lines, gas valve must be disconnected and isolated. See Figure 60. Gas valves Failure to follow the safety warnings exactly could can be damaged if subjected to pressures greater than result in serious injury, death, or property damage.
  • Page 41 Gas Pipe Capacity - FT³/HR (kL/HR) Nominal Length of 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 42: Electrical

    The unit is equipped with a field makeup box. The makeup Electrical box may be moved to the right side of the furnace to facilitate installation. Seal unused openings on left side ELECTROSTATIC DISCHARGE (ESD) with plugs removed from right side. Secure the excess wire to the existing harness to protect it from damage.
  • Page 43 Indoor Blower Speeds use an external relay. See Figure 69 for control board configuration. This terminal is energized in the heating When the thermostat is set to “FAN ON”, the indoor mode when the combustion air inducer is operating. blower will run continuously on the heating speed when there is no cooling or heating demand.
  • Page 44 045-2 045-3 070-2 070-3 090-3 090-4 110-4 110-5 135-5 DO NOT USE RED (LOW SPD) MOTOR LEAD FOR HEATING. LEAVE ON PARK TERMINAL FOR 070B2, 070BP2, 090C3, 090CP3, 110C4, 110CP4, 135D5, AND 135DP5 Figure 67. Typical Wiring Diagram Page 44 of 61 Issue 1716 507715-01...

  • Page 45: Unit Start-Up

    Terminal Designations Humidifier (120 VAC) LINE Input (120 VAC) XFMR Transformer (120 VAC) Electronic Air Cleaner (120 VAC) COOL Blower - Cooling Speed (120 VAC) HEAT Blower - Heating Speed (120 VAC) PARK Dead terminals to park alternate speed taps NEUTRALS Neutral terminals (120 VAC) Figure 69.
  • Page 46 Priming Condensate Trap Move gas valve switch to ON. See Figure 70. The condensate trap should be primed with water prior Replace the upper access panel. to start-up to ensure proper condensate drainage. Either 10. Turn on all electrical power to the unit. pour 10 fl.
  • Page 47 Gas Pressure Adjustment Start unit and allow 5 minutes for unit to reach steady state. Gas Flow (Approximate) While waiting for the unit to stabilize, observe the Seconds for One Revolution flame. Flame should be stable and should not lift from Natural burner.
  • Page 48 11U68 Pressure switch is factory set. No adjustment necessary. All models use the factory-installed pressure switch from 0-4500 feet (0-1371 m). GUH95A Pressure Switch Requirements at Varying Altitudes 0 - 4500 ft 4501 - 7500 ft 7501 - 10000 ft...

  • Page 49: Testing For Proper Venting And Sufficient Combustion Air For Non-Direct Vent Applications

    Testing for Proper Venting and Sufficient Combustion Air for Non-Direct Vent Applications Seal any unused openings in the venting system. Visually inspect the venting system for proper size WARNING and horizontal pitch. Determine there is no blockage CARBON MONOXIDE POISONING HAZARD or restriction, leakage, corrosion, or other deficiencies which could cause an unsafe condition.

  • Page 50: Other Unit Adjustments

    Thermostat Heat Anticipation Other Unit Adjustments Set the heat anticipator setting (if adjustable) according to the amp draw listed on the wiring diagram that is attached to the unit. Primary Limit The primary limit is located on the heating compartment Electrical vestibule panel.

  • Page 51: Blower Performance Guh92A

    Blower Performance GUH92A GUH92A 045*B2 Performance (Less Filter) External Air Volume / Watts at Various Blower Speeds Static High Medium-High Medium-Low Pressure Watts Watts Watts Watts in. w.c. 0.00 1140 0.10 1135 0.20 1125 0.30 1090 0.40 1065 0.50 1020 0.60 0.70 0.80...
  • Page 52 GUH92A 070*B3 Performance (Less Filter) External Air Volume / Watts at Various Blower Speeds Static High Medium-High Medium-Low Pressure Watts Watts Watts Watts in. w.c. 0.00 1615 1355 1140 1030 0.10 1565 1365 1150 1020 0.20 1535 1340 1150 1025 0.30 1440 1300...
  • Page 53 GUH92A 110*C4 Performance (Less Filter) External Air Volume / Watts at Various Blower Speeds Static High Medium-High Medium-Low Pressure Watts Watts Watts Watts in. w.c. 0.00 2030 1750 1425 1225 0.10 1950 1755 1430 1215 0.20 1935 1675 1455 1230 0.30 1885 1660...

  • Page 54: Blower Performance Guh95A

    Blower Performance GUH95A GUH95A 070*B3 Performance (Less Filter) External Air Volume / Watts at Various Blower Speeds Static High Medium-High Medium-Low Pressure Watts Watts Watts Watts in. w.c. 0.00 1585 1340 1095 0.10 1560 1320 1085 0.20 1515 1300 1080 0.30...
  • Page 55 GUH95A 110*C5 Performance (Less Filter) Air Volume / Watts at Various Blower Speeds Bottom Return Air, Side Return Air with Optional Return Air Base, Single Side Return Air - Air volumes in bold require field fabricated External Return Air from Both Sides or Return Air from Bottom and One Side.

  • Page 56: Service

    Winterizing and Condensate Trap Care Service Turn off power to the furnace. Have a shallow pan ready to empty condensate water. Remove the clean out cap from the condensate trap WARNING and empty water. Inspect the trap then reinstall the ELECTRICAL SHOCK, FIRE, OR EXPLOSION clean out cap.
  • Page 57 19. Remove the primary limit from the vestibule panel. 41. Reconnect flame rollout switch wires. 20. Remove top cap screws to allow top cap to be 42. Reconnect sensor wire and reconnect 2 pin plug from tilted upward to allow clearance for removing heat ignitor.

  • Page 58: Planned Service

    Table 14. Diagnostic Codes Repair Parts List The following repair parts are available through Comfort-Aire / Century dealers. When ordering parts, include the complete furnace model number listed on the CSA nameplate. All service must be performed by a licensed professional installer (or equivalent), service agency, or gas supplier.

  • Page 59: Start-Up & Performance Checklist

    Start-Up & Performance Checklist UNIT SET UP Furnace: Model Number_______________ Serial Number_________________ SUPPLY Line Voltage GAS SUPPLY LP Propane Gas Natural Gas Piping Connections Tight Leak Tested Flter RETURN AIR Gas Supply Pressure DUCT SYSTEM SUPPLY AIR DUCT Sealed Insulated (if necessary) RETURN DUCT Sealed INTAKE / EXHAUST PIPE...
  • Page 60 UNIT OPERATION HEATING MODE COOLING MODE INDOOR BLOWER AMPS______ COMBUSTION SAMPLE CO CO PPM_______ TEMPERATURE DROP ______ Return Duct Temperature _________ INDOOR BLOWER AMPS______ Supply Duct Temperature _______ Temperature Drop = _________ TEMPERATURE RISE TOTAL EXTERNAL STATIC (dry coil) Supply Duct Temperature ________ Supply External Static _______ Return Duct Temperature _____...
  • Page 61 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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