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507712-01

Page 1  of  36

Issue 1642

Table of Contents

Unit Dimensions ............................................................2

Parts Arrangement.........................................................3

GDD80A Gas Furnace...................................................4

Shipping and Packing List .............................................4

Safety Information .........................................................4

Use of Furnace as a Construction Heater .....................5

General ..........................................................................6

Combustion, Dilution & Ventilation Air ...........................6

Setting Equipment .........................................................9

Filters ...........................................................................12

Duct System ................................................................12

Venting.........................................................................12

Gas Piping ...................................................................20

Electrical ......................................................................22

Wiring Diagrams ..........................................................24

Unit Start-Up ................................................................27

Other Unit Adjustments................................................29

Service.........................................................................31

Repair Parts List ..........................................................34

Start-Up & Performance Check List ............................35

This manual must be left with the homeowner for future reference.

INSTALLATION INSTRUCTIONS

GDD80A

Warm Air Gas Furnace 

Downflow 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.

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.

   WARNING

As with any mechanical equipment, personal injury can 

result from contact with sharp sheet metal edges. Be 

careful when you handle this equipment. 

   CAUTION

(P) 507712-01

*P507712-01*

Manufactured By

Comfort-Aire / Century

1900 Wellworth Ave.

Jackson, MI 49203

Summary of Contents for GDD80A

Page 1: ...ON INSTRUCTIONS GDD80A Warm Air Gas Furnace Downflow 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...

Page 2: ...ng Unit Dimensions Model Number A B C D GDD80A in mm in mm in mm in mm 045 3 14 1 2 368 13 3 8 340 13 330 4 3 4 121 070 2 070 3 090 3 17 1 2 446 16 3 8 416 16 406 6 1 4 159 090 4 110 4 21 533 19 7 8 5...

Page 3: ...sue 1642 Figure 1 BLOWER ASSEMBLY CABINET CONTROL BOX INTERNAL FLUE PIPE ASSEMBLY FLUE CHASE HEAT EXCHANGER GAS VALVE ACCESS PANEL BURNER BOX ASSEMBLY COMBUSTION AIR INDUCER ROLLOUT LOCATED INSIDE BUR...

Page 4: ...ng to the current National Fuel Gas Code ANSI Z223 1 The National Fuel Gas Code is available from the following address American National Standards Institute Inc 11 West 42nd Street New York NY 10036...

Page 5: ...bile homes recreational vehicles or outdoors Use of Furnace as a Construction Heater These units are not recommended for construction heating during any phase of construction Very low return air tempe...

Page 6: ...lem in bringing in sufficient outdoor air for combustion Infiltration provided all the air that was needed In today s homes tight construction practices make it necessary to bring in air from outside...

Page 7: ...taining 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 This is especially important when the fu...

Page 8: ...gs shall each have a free area of at least one square inch per 4 000 Btu 645 mm per 1 17 kW per hour of the total input rating of all equipment in the enclosure Inlet Air from Crawlspace Outlet Air to...

Page 9: ...met used with a flexible mounting leg The bolt and washer must be removed before the furnace is placed into operation After the bolt and washer have been removed the rigid leg will not touch the blowe...

Page 10: ...nsate trap and vent pipe installation The furnace may be installed on a combustible wood floor if an optional additive base is installed between the furnace and the combustible floor Installation on N...

Page 11: ...binet See Figure 13 NOTE Downflow combustible flooring kit is not used 1 Refer to reverse flow coil installation instructions for correctly sized opening in floor and installation of cabinet 2 When co...

Page 12: ...se flow of the flue gas may result in incomplete combustion and the formation of carbon monoxide gas This toxic gas might then be distributed throughout the house by the furnace duct system Venting A...

Page 13: ...red to be an exterior chimney An exterior masonry chimney that is not tile lined must be lined with B 1 vent or a listed insulated flexible metal vent An exterior tile lined chimney that is sealed and...

Page 14: ...provided venting tables 3 The minimum vent capacity determined by the sizing tables must be less than the low fire input rating and the maximum vent capacity must be greater than the high fire input...

Page 15: ...st be resized Removal of the Furnace from Common Vent In the event that an existing furnace is removed from a venting system commonly run with separate gas appliances the venting system is likely to b...

Page 16: ...15 136 20 226 22 339 5 22 65 30 130 39 219 49 330 10 29 59 40 121 51 206 64 315 15 35 53 48 112 61 195 75 301 20 0 0 97 0 202 0 349 0 540 2 10 75 14 149 18 250 20 377 5 21 71 29 143 38 242 47 367 10 2...

Page 17: ...69 57 136 80 225 115 337 5 51 63 75 128 102 216 144 326 10 NR NR 95 116 128 201 182 308 15 NR NR NR NR 158 186 220 290 20 0 35 96 54 200 78 346 114 537 2 37 74 56 148 78 248 113 375 5 50 68 73 140 10...

Page 18: ...2 52 146 69 220 15 1 21 50 33 89 47 142 64 220 2 22 53 35 96 49 153 66 235 3 24 55 36 102 51 163 68 248 20 1 21 54 33 99 46 157 62 246 2 22 57 34 105 48 167 64 259 3 23 60 35 110 50 176 66 271 30 1 20...

Page 19: ...60 77 110 112 175 169 278 2 51 62 81 115 117 185 177 290 3 54 64 85 119 122 193 185 300 NOTE Single appliance venting configurations with zero lateral lengths are assumed to have no elbows in the vent...

Page 20: ...quire the installation of a manual main shut off valve and union furnished by the installer external to the unit The union must be of the ground joint type Compounds used on threaded joints of gas pip...

Page 21: ...8 07 260 7 36 240 6 80 220 6 23 205 5 80 195 5 52 1 1 4 31 75 1 380 35 052 1400 39 64 950 26 90 770 21 80 660 18 69 580 16 42 530 15 01 490 13 87 460 13 03 430 12 18 400 11 33 1 1 2 38 1 1 610 40 894...

Page 22: ...matic wiring diagram and troubleshooting and Figure 25 for field wiring The power supply wiring must meet Class I restrictions Protected by either a fuse or circuit breaker select circuit protection a...

Page 23: ...lay Generator Use Voltage Requirements The following requirements must be kept in mind when specifying a generator for use with this equipment The furnace requires 120 volts 10 Range 108 volts to 132...

Page 24: ...507712 01 Page 24 of 36 Issue 1642 Figure 24 Wiring Diagrams...

Page 25: ...LOWER MOTOR B3 OUTDOOR UNIT C R G Y W Y G R C W Y C R ON OFF B6 3 5 BURNERS IGNITOR FLAME SENSOR S47 FLAME ROLLOUT SWITCH S47 FLAME ROLLOUT SWITCH R33 J159 P159 3 Field supplied ACC Wire 5 S145 is use...

Page 26: ...RALS RED GREEN W C R Y G C 2 3 4 1 1 2 3 4 5 6 7 8 9 10 11 12 3 AMP 32 VAC FUSE Terminal Designations HUM Humidifier 120 VAC LINE Input 120 VAC XFMR Transformer 120 VAC EAC Electronic Air Cleaner 120...

Page 27: ...sing property damage personal injury or death WARNING Gas Valve Operation See Figure 27 1 STOP Read the safety information at the beginning of this section 2 Set the thermostat to the lowest setting 3...

Page 28: ...f flame is not detected after first ignition trial the ignition control will repeat steps 3 and 4 four more times before locking out the gas valve The ignition control will then automatically repeat s...

Page 29: ...set and require no adjustment Flame Rollout Switches This manually reset switches are located on the front of the burner box Pressure Switch The pressure switch is located in the heating compartment a...

Page 30: ...Nat 4 5 10 0 No Change 0 0625 3 5 No Change 0 0625 3 5 No Change 0 0625 3 3 51W01 0 0550 3 5 LP Propane 11 0 13 0 11K50 0 034 10 0 11K50 0 034 10 0 11K50 0 034 10 0 11K45 0 032 10 0 090 Nat 4 5 10 0 N...

Page 31: ...ill break and remake thermostat demand to the furnace and automatically reset the integrated control to begin the ignition sequence Service ELECTRICAL SHOCK FIRE OR EXPLOSION HAZARD Failure to follow...

Page 32: ...r manifold assembly to the vestibule panel and remove the assembly from the unit 7 Remove screws securing burner box and remove burner box 8 NOx units only Remove screw securing NOx insert Remove NOx...

Page 33: ...other sources of ignition to check for gas leaks CAUTION 24 If a leak is detected shut gas and electricity off and repair leak 25 Repeat steps 24 and 26 until no leaks are detected 26 Replace access p...

Page 34: ...ofessional installer or equivalent service agency or gas supplier Cabinet Parts Upper access panel Blower panel Top cap Control Panel Parts Transformer Integrated control Door interlock switch Circuit...

Page 35: ...507712 01 Page 35 of 36 Issue 1642 UNIT SET UP Start Up Performance Check List...

Page 36: ...507712 01 Page 36 of 36 Issue 1642 UNIT OPERATION...

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