COMFORT-AIRE Century GDD95C Installation Instructions Manual
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COMFORT-AIRE Century GDD95C Installation Instructions Manual

Warm air gas furnace downflow air discharge
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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.
Unit Dimensions ..........................................................2
Parts Arrangement.......................................................3
Gas Furnace ................................................................4
Shipping and Packing List ...........................................4
Safety Information .......................................................4
General ........................................................................6
Combustion, Dilution & Ventilation Air .........................6
Installation ...................................................................9
Filters .........................................................................12
Duct System ..............................................................12
Venting Practices .......................................................14
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
507735-03
INSTALLATION INSTRUCTIONS
Warm Air Gas Furnace
Downflow Air Discharge
This manual must be left with the homeowner for future reference.

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WARNING
Save these instructions for future reference
GDD95C
Condensate Piping ....................................................28
Gas Piping .................................................................31
Electrical ....................................................................34
Unit Start-Up ..............................................................37
Air for Non-Direct Vent Applications ..........................41
Other Unit Adjustments..............................................42
Blower Performance Data .........................................43
Service.......................................................................44
Planned Service ........................................................46
Repair Parts List ........................................................52
As with any mechanical equipment, personal injury can
result from contact with sharp sheet metal edges. Be
careful when you handle this equipment.
Issue 1933
CAUTION
*P507735-03*
(P) 507735-03
Page 1 of 53

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Summary of Contents for COMFORT-AIRE Century GDD95C

  • Page 1: Table Of Contents

    (or careful when you handle this equipment. equivalent), service agency or the gas supplier. Manufactured By *P507735-03* Comfort-Aire / Century 1900 Wellworth Ave. (P) 507735-03 Jackson, MI 49203 Save these instructions for future reference...

  • Page 2: Unit Dimensions

    Unit Dimensions 9/16 (14) COMBUSTION AIR INTAKE Return Air Opening EXHAUST AIR OUTLET 2−1/16 (52) 9/16 2−1/4 (57) (14) (127) TOP VIEW 27−3/4 1 (25) Front Panel (705) 19−7/16 9/16 9/16 (494) (14) (14) FLOW ELECTRICAL INLET (Either Side) (838) 2 (51) Either Side CONDENSATE...

  • Page 3: Parts Arrangement

    Parts Arrangement CONTROL BOX (Includes integrated control, transformer and door switch) BAG ASSEMBLY BLOWER MOTOR (hidden) BLOWER COMPARTMENT ACCESS PANEL COMBUSTION AIR INDUCER BLOWER DECK HEATING PRIMARY LIMIT COMPARTMENT ACCESS PANEL COLD END HEADER BOX HEAT EXCHANGER GAS VALVE BURNER BOX ASSEMBLY (includes flame sensor, rollout switches and ignitor) Figure 1.

  • Page 4: Gas Furnace

    Gas Furnace Shipping and Packing List This Category IV gas furnace is shipped ready for 1 - Assembled Gas Unit installation in the downflow position. 1 - Bag assembly containing the following: 1 - Snap bushing The furnace is equipped for installation in natural gas applications.
  • Page 5 In order to ensure proper unit operation in non-direct vent Heating Unit Installed Parallell to Air Handler Unit applications, combustion and ventilation air supply must be provided according to the current National Fuel Gas Code or CSA-B149 standard. Locations and Clearances AIR HANDLER GAS UNIT This furnace is CSA International certified for installation...

  • Page 6: General

    FAILURE TO FOLLOW THE ABOVE INSTALLATION INSTRUCTIONS VOIDS MANUFACTURER’S EQUIPMENT LIMITED WARRANTY. COMFORT-AIRE / If this unit is installed as a Non-Direct Vent Furnace, follow CENTURY DISCLAIMS ALL LIABILITY IN CONNECTION the guidelines in this section. WITH INSTALLER’S FAILURE TO FOLLOW THE ABOVE INSTALLATION INSTRUCTIONS.
  • Page 7 not separated by a door. Though an area may appear to be unconfined, it might be necessary to bring in outdoor air WARNING for combustion if the structure does not provide enough air by infiltration. Insufficient combustion air can cause headaches, nausea, dizziness or asphyxiation.
  • Page 8 When communicating with the outdoors through horizontal ducts, each opening shall have a minimum free area of 1 square inch (645 mm²) per 2,000 Btu (.56 kW) per hour of the total input rating of all equipment in the enclosure. See ROOF TERMINATED EXHAUST PIPE Figure 7.

  • Page 9: Installation

    Installation Ventilation Louvers Inlet Air Roof Terminated (Minimum 12 in. Exhaust Pipe (305mm) above Setting Equipment Attic Floor) *Intake Debris CAUTION Screen (Provided) Do not install the furnace on its front, back or in the Furnace horizontal position. See Figure 12. Do no connect the return air ducts to the back of the furnace.
  • Page 10 AIR FLOW AIR FLOW AIR FLOW Left Side Right Side 1/2" max. SIDE VIEW FRONT VIEW SIDE VIEW Unit must be level side−to−side. Unit may be positioned Bottom from level to 1/2" toward the front to aid in draining. Figure 11. Setting Equipment *Front *Front Back...
  • Page 11 Check fiberglass strips on the combustible flooring base to make sure they are properly glued and FURNACE positioned. Lower supply air plenum into the combustible flooring base until plenum flanges seal against fiberglass PROPERLY strips. SIZED FLOOR SUPPLY AIR NOTE: Be careful not to damage fiberglass strips. OPENING PLENUM Check for a tight seal.

  • Page 12: Filters

    Return Air Plenum PLENUM NOTE: Return air must not be drawn from a room where SECURE FROM (Field Provided) OUTSIDE CABINET this furnace, or any other gas-fueled appliance (i.e., water heater), or carbon monoxide-producing device (i.e., wood fireplace) is installed. CABINET When return air is drawn from a room, a negative pressure SEALING STRIP...
  • Page 13 Pipe & Fittings Specifications All pipe, fittings, primer and solvent cement must conform IMPORTANT with American National Standard Institute and the American Society for Testing and Materials (ANSI/ASTM) standards. The exhaust and intake connections are made of PVC. The solvent shall be free flowing and contain no lumps, Use PVC primer and solvent cement when using PVC undissolved particles or any foreign matter that adversely vent pipe.

  • Page 14: Venting Practices

    Canadian Applications Only After assembly, wipe excess cement from pipe at end of fitting socket. A properly made joint will show a bead Pipe, fittings, primer and solvent cement used to vent around its entire perimeter. Any gaps may indicate (exhaust) this appliance must be certified to ULC S636 and an improper defective assembly due to insufficient supplied by a single manufacturer as part of an approved...
  • Page 15 In some applications which permit the use of several What is the altitude? 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. Use Table 7 to find max pipe length.
  • Page 16 Maximum Allowable Intake or Exhaust Vent Length in Feet Standard Termination at Elevation 0 − 10,000 ft. Number 1-1/2” Pipe 2” Pipe 2-1/2” Pipe 3” Pipe of 90° Capacity Capacity Capacity Capacity Elbows Used Concentric Termination Elevation 0 − 10,000 ft. Number 1-1/2”...
  • Page 17 Maximum Allowable Exhaust Vent Lengths with Furnace Installed in a Closet or Basement Using Ventilated Attic or Crawl Space for Intake Air in Feet Standard Termination at Elevation 0 − 10,000 ft. Number 1-1/2” Pipe 2” Pipe 2-1/2” Pipe 3” Pipe of 90°...
  • Page 18 Pipe size determined in table 7. 2” 2” 2” 2” 2” INTAKE EXHAUST TOP VIEW NOTE: 1-1/2” Vent Pipe Diameter Allowed Only on 045/070 Units TRANSITION 3” 1-1/2” *2” 3” TRANSITION TRANSITION *2” *2” *2” * When transitioning up in pipe size, use the shortest length of 2” PVC pipe possible. NOTE: Exhaust pipe and intake pipe must be the same diameter.
  • Page 19 General Guidelines for Vent Terminations Ventilation Louvers In Non-Direct Vent applications, combustion air is taken Inlet Air Roof Terminated (Minimum 12 in. from indoors and the flue gases are discharged to the Exhaust Pipe (305mm) above outdoors. This unit is then classified as a non-direct vent, Attic Floor) Category IV gas furnace.
  • Page 20 IMPORTANT For Canadian Installations Only In accordance to CSA International B149 installation codes, the minimum allowed distance between the combustion air intake inlet and the exhaust outlet of other appliances shall not be less than 12 inches (305 mm). Maximum Allowable Exhaust Vent Pipe Length (in ft.) without Insulation in Unconditioned Space for Winter Design Temperatures Single - Stage High Efficiency Furnace Unit Input Size...
  • Page 21 ‡ 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 27. Vent Termination Clearances...
  • Page 22 ‡ 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 28. Vent Termination Clearances...
  • Page 23 Details of Intake and Exhaust Piping 3” (76MM) MIN. SIZE PER EXHAUST PIPE Inches (MM) Terminations for Direct Vent Installations TERMINATION SIZE NOTE: In Direct Vent installations, combustion air is taken REDUCTION TABLE from outdoors and flue gases are discharged to outdoors. UNCONDITIONED ATTIC SPACE 8”...
  • Page 24 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 25 FIELD-PROVIDED REDUCER MAY BE REQUIRED TO ADAPT DIFFERENT VENT PIPE SIZE TO TERMINATION OUTSIDE INTAKE WALL EXHAUST EXHAUST Inlet Air Minimum 12 in. Exhaust Furnace 12” (305mm) Min. Pipe (305MM) above INTAKE INTAKE CLAMP above grade or grade or snow (Not Furnished) average snow accumulation...
  • Page 26 Details of Exhaust Piping Terminations for Non- Direct Vent Applications Exhaust pipe 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 27 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 28: Condensate Piping

    Condensate Piping This unit is designed for either right or left side exit of condensate piping in downflow applications. Refer to Figure 45 for condensate trap locations. NOTE: If necessary the condensate trap may be installed up to 5” away using PVC pipe from the furnace. Piping from furnace must slope down a minimum of 1/4”...
  • Page 29 Figure 47. Unit with Evaporator Coil Figure 48. Evaporator Coil Using a Common Drain CAUTION A separate drain line must be run to the drain from the condensate trap to ensure proper drainage and pressure switch operation. DO NOT connect the condensate trap drain into the drain line from the evaporator coil.
  • Page 30 Figure 50. Trap Drain Assembly Using 1/2” PVC or 3/4” PVC Page 30 of 53 Issue 1933 507735-03...

  • Page 31: Gas Piping

    Gas Piping IMPORTANT Compounds used on threaded joints of gas piping must be resistant to the actions of liquefied petroleum gases. CAUTION If a flexible gas connector is required or allowed by the authority that has jurisdiction, black iron pipe shall Leak Check be installed at the gas valve and extend outside the After gas piping is completed, carefully check all piping...
  • Page 32 Left Side Piping MANUAL (Standard) AUTOMATIC MAIN SHUT−OFF GAS VALVE MANUAL VALVE AUTOMATIC (with manual Plug MAIN SHUT−OFF (With 1/8 in. NPT GAS VALVE shut−o valve) VALVE Plugged Tap (with manual Plug (With 1/8 in. NPT Shown) shut−o valve) Plugged Tap Shown) GROUND JOINT UNION...
  • Page 33 Removal of the Furnace from Common Vent Seal any unused openings in the common venting system. In the event that an existing furnace is removed from a venting system commonly run with separate gas Inspect the venting system for proper size and appliances, the venting system is likely to be too large to horizontal pitch.

  • Page 34: Electrical

    The power supply wiring must meet Class I restrictions. Electrical Protected by either a fuse or circuit breaker, select circuit protection and wire size according to unit nameplate. ELECTROSTATIC DISCHARGE (ESD) NOTE: Unit nameplate states maximum current draw. Maximum Over-Current Protection allowed is 15 AMP. Precautions and Procedures Holes are on both sides of the furnace cabinet to facilitate wiring.
  • Page 35 Indoor Blower Speeds mode when the combustion air inducer is operating and the pressure switch is closed. Any humidifier rated up to When the thermostat is set to “FAN ON”, the indoor 0.5 amp can be connected to this terminal with the ground blower will run continuously on the fan speed when leg of the circuit connected to ground or the “C”...
  • Page 36 045B3 070B4 090C4 110C5 Figure 57. Typical Wiring Diagram Page 36 of 53 Issue 1933 507735-03...

  • Page 37: Unit Start-Up

    Terminal Designations 120 HUM Humidifier (120 VAC) LINE Input (120 VAC) XFMR Transformer (120 VAC) CIRC Indoor Blower (120 VAC) Electronic Air Cleaner (120 VAC) COOL Blower - Cooling Speed (24 VAC) HEAT Blower - Heating Speed (24 VAC) Blower - Fan Speed (24 VAC) PARK Dead terminals to park all speed taps NEUTRALS...
  • Page 38 Priming Condensate Trap Gas Valve Shown In “ON’ Position The condensate trap should be primed with water prior to start-up to ensure proper condensate drainage. Either MANIFOLD MANIFOLD pour 10 fl. oz. (300 ml) of water into the trap, or follow PRESSURE PRESSURE these steps to prime the trap:...
  • Page 39 Manifold Pressure Measurement If flame is not detected after first ignition trial, the ignition control will repeat steps 3 and 4 four more 1. Remove the threaded plug from the outlet side of times before locking out the gas valve. The ignition the gas valve and install a field provided barbed control will then automatically repeat steps 1 through fitting.
  • Page 40 Burner Orifice Conversion Kits at Varying Altitudes 0 - 7,500 ft 7,501 - 10,000 ft (0 - 2,286 m) (2,286 - 3048m) Capacity High Altitude High Altitude LP/ Natural to LP/ LP/Propane to Natural Burner Propane Burner Propane Natural Orifice Kit Orifice Kit 11K50†...

  • Page 41: 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 42: Other Unit Adjustments

    Other Unit Adjustments Primary Limit The primary limit is located on the heating compartment NO JUMPER vestibule panel. This limit is factory set and requires no To adjust fan−o timing, reposition jumper across pins to adjustment. achieve desired setting. 60 Second 90 Second 120 Second 180 Second...

  • Page 43: Blower Performance Data

    Blower Performance Data GDD95C045B3M Performance (Less Filter) Air Volume / Watts at Different Blower Speeds External Bottom Return Air, Side Return Air with Optional Return Air Base, Return Air from Both Sides or Return Air from Static Bottom and One Side. Pressure High Medium-High...

  • Page 44: Service

    GDD95C110C5M Performance (Less Filter) Air Volume / Watts at Different Blower Speeds External Bottom Return Air, Side Return Air with Optional Return Air Base, Return Air from Both Sides or Return Air from Static Bottom and One Side. Pressure High Medium-High Medium Medium-Low...
  • Page 45 Blower Disconnect wires from flame rollout switches. Check the blower wheel for debris and clean if necessary. Loosen clamps at vent elbow. Disconnect condensate The blower motors are pre-lubricated for extended bearing drain tubing from flue collar and remove the vent life.

  • Page 46: Planned Service

    24. Reinstall electrical junction box. 10. Reinstall the gas valve manifold assembly. Reconnect the gas supply line to the gas valve. Reinstall the 25. Reinstall the combustion air inducer. Reconnect the burner box cover. combustion air inducer to the wire harness. 11.
  • Page 47 -02 Integrated Control LED Codes Red LED Flash Code Diagnostic Codes / Status of Furnace LED Off No power to control or control hardware fault detected Heartbeat Control powered - displayed during all modes of operation if no errors are detected 1 Flash Reverse line voltage polarity 2 Flashes...
  • Page 48 Troubleshooting: Heating Sequence of Operation Page 48 of 53 Issue 1933 507735-03...
  • Page 49 Troubleshooting: Heating Sequence of Operation (continued) 507735-03 Issue 1933 Page 49 of 53...
  • Page 50 Troubleshooting: Cooling Sequence of Operation Page 50 of 53 Issue 1933 507735-03...
  • Page 51 Troubleshooting: Continuous Fan Sequence of Operation 507735-03 Issue 1933 Page 51 of 53...

  • Page 52: Repair Parts List

    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 53 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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