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507867-02P

Page 1 of 55

Issue 1933

INSTALLATION INSTRUCTIONS

GUH92C

Warm Air Gas Furnace

Upflow/Horizontal Left and Right Air Discharge

Save these instructions for future reference

 

(P) 507867-02P

*P507867-02P*

Manufactured By

Comfort-Aire / Century

1900 Wellworth Ave.

Jackson, MI 49203

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

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

Table of Contents

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 ....................................................

33

Gas Piping

 .................................................................

36

Electrical ....................................................................

39

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

42

Testing for Proper Venting and Sufficient Combustion 

Air for Non-Direct Vent Applications ..........................

46

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

46

Blower Performance GUH92C ..................................

48

Service.......................................................................

51

Planned Service ........................................................

54

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

54

Summary of Contents for GUH92C

Page 1: ...l 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 Table of Contents Unit Dimensions 2 Parts Arrangement 3 Gas Furnace 4 Shipping and Pac...

Page 2: ...le side return air with optional RAB Return Air Base 3 Bottom return air 4 Return air from both sides 5 Bottom and one side return air See Blower Performance tables for additional information 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 Capa...

Page 3: ...Valve Combustion Air Inducer Blower Access Door Combustion Air Pressure Prove Switch Cold End Header Box Control Box includes integrated ignition control transformer and interlock switch Blower Assembly Bag Assemblies Cabinet Top Cap Heat Exchanger Assembly Flexible No HJB Exhaust Collar ...

Page 4: ... bushing 1 Snap Plug 1 Wire tie 1 Condensate trap 1 Condensate trap cap 1 Condensate trap clamp 1 2 diameter debris screen 1 3 4 Threaded street elbow Check equipment for shipping damage If you find any damage immediately contact the last carrier Please refer to specification sheets for available accessories Safety Information Improper installation adjustment alteration service or maintenance can ...

Page 5: ...urnace must be adjusted to obtain a temperature rise within the range specified on the unit nameplate Failure to do so may cause erratic limit operation and premature heat exchanger failure This furnace must be installed so that its electrical components are protected from water Installed in Combination with a Cooling Coil When this furnace is used with cooling units Figure 4 it shall be installed...

Page 6: ...L OF THE FOLLOWING CRITERIA ARE MET a Furnace must be in its final location The vent system must be permanently installed per these installation instructions b Furnace must be installed as a two pipe system and one hundred percent 100 outdoor air must be provided for combustion air requirements during construction c A room thermostat must control the furnace The use of fixed jumpers that will prov...

Page 7: ...sion from the National Fuel Gas Code ANSI Z223 1 NFPA 54 This reprinted material is not the complete and official position of ANSI on the referenced subject which is represented only by the standard in its entirely In Canada refer to the CSA B149 Installation codes Do not install the furnace in a corrosive or contaminated atmosphere Meet all combustion and ventilation air requirements as well as a...

Page 8: ... be within 12 305 mm of the top of the enclosure and one within 12 305 mm of the bottom These openings must communicate directly or by ducts with the outdoors or spaces crawl or attic that freely communicate with the outdoors or indirectly through vertical ducts Each opening shall have a minimum free area of 1 square inch per 4 000 Btu 645 mm per 59 kW per hour of total input rating of all equipme...

Page 9: ... Minimum 12 in 305mm above Crawl Space Floor Coupling or 3 in to 2 in Transition Field Provided 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 645mm2 per 1 17kW per hour of the total input rating of all equipment in the enclosure Figure 10 Equipment in Confined Space All Air from Outside Shipping Bolt Remo...

Page 10: ...rnace can result in personal injury or death Combustion and flue products must never be allowed to enter the return air system or air in the living space Use sheet metal screws and joint tape to seal return air system to furnace In platform installations with furnace return the furnace should be sealed airtight to the return air plenum A door must never be used as a portion of the return air duct ...

Page 11: ...ing SIDE VIEW 3 1 4 83 1 23 584 Overall Maximum 584 23 3 4 19 1 22 7 16 570 Overall Maximum SIDE RETURN AIR OPENINGS Either Side 5 5 8 143 1 Minimum 11 279 2 Maximum 14 356 683 26 7 8 7 1 4 184 FURNACE FRONT AIR FLOW IF BASE IS USED WITHOUT IAQ CABINET A SINGLE RETURN AIR PLENUM MUST COVER BOTH UNIT AND RETURN AIR BASE OPENINGS INDOOR AIR QUALITY CABINET AIR BASE OPTIONAL RETURN 17 1 2 446 B Width...

Page 12: ...tion Installation Clearances Top Plenum 1 in 25 mm Front 0 Back 0 Sides 0 Vent 0 Floor 0 Front clearance in alcove installation must be 24 in 610 mm Maintain a minimum of 24 in 610 mm for front service access Allow proper clearances to accommodate condensate trap For installations on a combustible floor do not install the furnace directly on carpeting tile or other combustible materials other than...

Page 13: ... 16 Filters This unit is not equipped with a filter or rack Afield provided filter is required for the unit to operate properly Table 1 list recommended filter sizes A filter must be in place whenever the is operating Table 1 Furnace Cabinet Width Filter Size Side Return Bottom Return B 17 1 2 16 x 25 x 1 1 16 x 25 x 1 1 C 21 20 x 25 x 1 1 Duct System Use industry approved standards to size and in...

Page 14: ...nt pipe hangers Uniformly apply a liberal coat of PVC primer for PVC or use a clean dry cloth for ABS to clean inside socket surface of fitting and male end of pipe to depth of fitting socket Canadian Applications Only Pipe fittings primer and solvent cement used to vent exhaust this appliance must be certified to ULC S636 and supplied by a single manufacturer as part of an approved vent exhaust s...

Page 15: ...t to pipe and while both inside socket surface and end of pipe are wet with cement forcefully insert end of pipe into socket until it bottoms out Turn PVC pipe 1 4 turn Capacity VENT PIPE DIA in STANDARD CONCENTRIC Outdoor Exhaust Accelerator Dia X Length Outdoor Exhaust Accelerator Dia X Length Flush Mount Kit 1 1 2 Concentric Kit 2 Concentric Kit 3 Concentric Kit 1 1 2 X 12 2 X 12 51W11 71M80 or...

Page 16: ...o blockage restriction leakage corrosion or other deficiencies which could cause an unsafe condition 3 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 Turn ON clothes dryers and any appliances not connected to the common venting system Turn ON any exhaust fans ...

Page 17: ...as central furnace NOTE In non Direct Vent installations combustion air is taken from indoors and flue gases are discharged outdoors In Direct Vent installations combustion air is taken from outdoors and flue gases are discharged outdoors Intake and exhaust pipe sizing Size pipe according to Table 4 and Table 5 through Table 6 Table 4 lists the minimum vent pipe lengths permitted Table 5 and Table...

Page 18: ...block the terminations IMPORTANT Use Figure 24 to correctly size vent pipe diameter 045 070 090 110 Standard or Concentric See Table 3 Intake or Exhaust 1 1 2 2 2 1 2 or 3 Furnace capacity 1 Which termination 2 Which needs most elbows 3 How many 4 Desired pipe size 5 What is the altitude 6 Use Table 5 or Table 6 to find max pipe length 7 Figure 24 ...

Page 19: ...n a 75 60 28 n a 97 97 78 78 9 36 21 70 55 23 92 92 73 73 10 31 16 65 50 18 87 87 68 68 Concentric Termination Elevation 0 10 000 ft Number of 90 Elbows Used 1 1 2 Pipe 2 Pipe 2 1 2 Pipe 3 Pipe Capacity Capacity Capacity Capacity 045 070 090 110 045 070 090 110 045 070 090 110 045 070 090 110 1 20 15 n a n a 68 53 37 17 100 85 59 34 116 116 109 109 2 15 10 63 48 32 12 95 80 54 29 111 111 104 104 3...

Page 20: ... 82 82 63 63 8 31 16 60 45 13 77 77 58 58 9 26 11 55 40 8 72 72 53 53 NOTE Additional vent pipe and elbows used to terminate the vent pipe outside the structure must be included in the total vent length calculation TYPICAL EXHAUST PIPE CONNECTIONS IN UPFLOW DIRECT OR NON DIRECT VENT APPLICATIONS When transitioning up in pipe size use the shortest length of 2 PVC pipe possible When transitioning do...

Page 21: ...n horizontal runs of exhaust pipe When transitioning up in pipe size use the shortest length of 2 PVC pipe possible When transitioning down in pipe size use at least 1 foot of 2 PVC pipe NOTE Exhaust pipe and intake pipe must be the same diameter Figure 26 Figure 27 TYPICAL INTAKE PIPE CONNECTIONS IN UPFLOW DIRECT OR NON DIRECT VENT APPLICATIONS 2 2 2 2 or AIR INTAKE 2 TRANSITION 3 2 2 1 1 2 or TR...

Page 22: ...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 Follow the next two steps when installing the unit in Direct Vent applications where combustion air is taken from outdoors and flue gases are discharged outdoors The provided air intake screen must n...

Page 23: ...oose insulation or other items that may clog the debris screen 2 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 6 If 3 diameter pipe is used reduce to 2 diameter pipe at the termination point to accommodate the debris screen 3 Use a sheet metal screw to secure the intake pipe to the connector...

Page 24: ... 2 PP PVC 2 PP PVC 2 PP 1 1 2 in 25 N A 25 N A N A N A N A N A 2 in 18 16 31 28 50 48 30 30 2 1 2 in 13 N A 24 N A 42 N A 56 N A 3 in 9 9 18 18 35 35 47 47 20 to 1 7 to 17 1 1 2 in 15 N A 20 N A N A N A N A N A 2 in 9 8 18 16 32 29 30 30 2 1 2 in 5 N A 13 N A 24 N A 34 N A 3 in N A N A 8 8 19 19 26 26 0 to 20 18 to 29 1 1 2 in 10 N A 15 N A N A N A N A N A 2 in 5 3 12 10 22 19 30 27 2 1 2 in N A N...

Page 25: ...nce under veranda porch deck or balcony 12 Equal to or greater than soffit depth 3 feet 9m 12 3 feet 9m within a height 15 feet 4 5m above the meter regulator assembly 3 feet 9m 6 inches 152mm for appliances 10 000 Btuh 3kw 12 inches 305mm for appliances 10 000 Btuh 3kw and 100 000 Btuh 30kw 36 inches 9m for appliances 100 000 Btuh 30kw 3 feet 9m above if within 10 feet 3m horizontally 6 feet 1 8m...

Page 26: ...2mm for appliances 10 000 pliances 10 000 Btuh 3kw and 50 000 pliances 50 000 Btuh 15kw 6 inches 152mm for appliances 10 000 Btuh 3kw 12 inches 305mm for appliances 10 000 Btuh 3kw and 100 000 Btuh 30kw 36 inches 9m for appliances 100 000 Btuh 30kw 3 feet 9m above if within 10 feet 3m horizontally 6 feet 1 8m 7 feet 2 1m 12 inches 305mm 1 In accordance with the current ANSI Z223 1 NFPA 54 Natural ...

Page 27: ...49 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 IMPORTANT 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 s...

Page 28: ...e 44 6 On field supplied terminations a minimum distance between the end of the exhaust pipe and the end of the intake pipe without a termination elbow is 8 and a minimum distance of 6 with a termination elbow See Figure 44 7 If intake and exhaust piping must be run up a side wall to position above snow accumulation or other obstructions piping must be supported every 24 610 mm as shown in Figure ...

Page 29: ...ED TO ADAPT DIFFERENT VENT PIPE SIZE TO TERMINATION Figure 41 Direct Vent Concentric Wall Termination 71M80 69M29 or 60L46 US 44W92 or 44W93 Canada Figure 42 3 8 76MM 203MM STRAIGHT CUT OR ANGLE CUT IN DIRECTION OF ROOF SLOPE SHOULDER OF FITTINGS PROVIDE SUPPORT OF PIPE ON TOP PLATE ALTERNATE INTAKE PIPE INTAKE PIPE INSULATION optional EXTERIOR PORTION OF CHIMNEY INSULATE TO FORM SEAL SHEET METAL ...

Page 30: ...uld be connected to the 2 or 3 PVC flue pipe as shown in the illustration Do not use an accelerator in applications that include an exhaust termination tee The accelerator is not required 2 As required Flue gas may be acidic and may adversely affect some building materials If a side wall vent termination is used and flue gases will impinge on the building materials a corrosion resistant shield 24 ...

Page 31: ...EXHAUST LINES 12 305MM ABOVE AVE SNOW ACCUMULATION SIZE PER EXHAUST PIPE TERMINATION SIZE REDUCTION TABLE Figure 46 Non Direct Vent Field Supplied Wall Termination SIZE TERMINATION PER EXHAUST PIPE TERMINATION SIZE REDUCTION TABLE FIELD PROVIDED REDUCER MAY BE REQUIRED TO ADAPT DIFFERENT VENT PIPE SIZE TO TERMINATION Figure 47 Non Direct Vent Field Supplied Wall Termination Extermination SIZE TERM...

Page 32: ...Termination Drain Trap assembled Figure 49 Kit 51W18 USA 15Z70 Canada Parts Identification and Assembly Exhaust from Furnace To Termination Exhaust from Furnace To Termination Kit 51W18 is shown Figure 50 Crawl Space Vent Pipe Drain Trap Assembled Incorrectly Figure 51 Upflow or Downflow Furnace with Exhaust through Crawl Space KIT 51W18 USA Basement Floor To Termination 1 2 PVC to Code Approved D...

Page 33: ...fittings glue all joints Glue the provided drain trap as shown in Figure 58 Route the condensate line to an open drain Condensate line must maintain a 1 4 downward slope from the furnace to the drain Do not use copper tubing or existing copper condensate lines for drain line CAUTION 5 Install field provided vent on trap assembly as shown in Figure 53 through Figure 59 Trap must extend at least 1 a...

Page 34: ... Piping from furnace must slope down a minimum of 1 4 per ft toward trap 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 per ft toward trap Figure 57 Evaporator Coil Using a Common Drain Unit shown in horizontal left hand discharge position ...

Page 35: ...507867 02P Page 35 of 55 Issue 1933 Figure 58 Trap Drain Assembly Using 1 2 PVC or 3 4 PVC ...

Page 36: ... line through piping hole Gas line should not touch side of unit See Figure 61 and Figure 62 4 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 Install a drip leg in vertical pipe runs to serve as a trap for sediment or condensate 5 ...

Page 37: ...eted WARNING Figure 61 Gas Piping Upflow Applications NOTE BLACK IRON PIPE ONLY TO BE ROUTED INSIDE OF CABINET FIELD PROVIDED AND INSTALLED GROUND JOINT UNION DRIP LEG MANUAL MAIN SHUT OFF VALVE Upflow Application Right Side Piping Alternate Gas Valve GROUND JOINT UNION Upflow Application Left Side Piping Standard DRIP LEG MANUAL MAIN SHUT OFF VALVE Gas Valve Figure 62 Gas Piping Horizontal Applic...

Page 38: ...0 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 2100 59 46 460 41 34 1180 33 41 990 28 03 900 25 48 810 22 94 750 21 24 690 19 54 650 18 41 620 17 56 2 50 8 2 067 52 502 3950 111 85 2750 77 87 2200 62 30 1900 53 80 1680 47 57 1520 43 04 1400 39 64 1300 36 81 1220 34 55 1150 32 56 2 1 2 63 5 2 469 67 713 6300 178 39 4350 123 17 3520 99 67 3000 84 95 2650 75 04 2400...

Page 39: ...lower for service Complete the wiring connections to the equipment Use the provided unit wiring diagram and the field wiring diagram shown in Figure 66 Use 18 gauge wire or larger that is suitable for Class II rating for thermostat connections Electrically ground the unit according to local codes or in the absence of local codes according to the current National Electric Code ANSI HFPA No 70 for t...

Page 40: ...uously on the heating speed when there is no cooling or heating demand See Table 16 for allowable continuous circulation speeds 2 When the furnace is running in the heating mode the indoor blower will run on the heating speed 3 When there is a cooling demand the indoor blower will run on the cooling speed Generator Use Voltage Requirements The furnace requires 120 volts 10 Range 108 volts to 132 v...

Page 41: ...507867 02P Page 41 of 55 Issue 1933 045B3 070B3 090C3 090C4 110C4 110C5 Figure 67 Typical Wiring Diagram ...

Page 42: ...WARNING Danger of explosion Can cause injury or product or property damage Should the gas supply fail to shut off or if overheating occurs shut off the gas valve to the furnace before shutting off the electrical blower deck before performing any service procedure WARNING Before attempting to perform any service or maintenance turn the electrical power to unit OFF at disconnect switch CAUTION BEFOR...

Page 43: ...er to the unit 11 Set the thermostat to desired setting NOTE When unit is initially started steps 1 through 11 may need to be repeated to purge air from gas line 12 If the appliance will not operate follow the instructions Turning Off Gas to Unit and call your service technician or gas supplier Turning Off Gas to Unit 1 Set the thermostat to the lowest setting 2 Turn off all electrical power to th...

Page 44: ...tabilize observe the flame Flame should be stable and should not lift from burner Natural gas should burn blue 4 After allowing unit to stabilize for 5 minutes record manifold pressure and compare to value given in Table 12 NOTE Shut unit off and remove manometer as soon as an accurate reading has been obtained Take care to remove barbed fitting and replace threaded plug Proper Combustion Furnace ...

Page 45: ...lation of a gas valve regulator spring which is provided with the gas conversion Kit LP Kits include low line pressure switch Table 13 Burner Orifice Conversion Kits at Varying Altitudes Capacity 0 4500 ft 0 1371m 4501 7500 ft 1371 2286m 7501 10000 ft 2286 3048m 045 No Change 11U65 11U66 070 090 110 Pressure switch is factory set No adjustment necessary All models use the factory installed pressur...

Page 46: ...ed and other spaces of the building 4 Close fireplace dampers 5 Turn on clothes dryers and any appliances not connected to the venting system Turn on any exhaust fans such as range hoods and bathroom exhausts so they will operate at maximum speed Do not operate a summer exhaust fan 6 Follow the lighting instruction to place the appliance being inspected into operation Adjust thermostat so applianc...

Page 47: ...el in place Motor Nameplate__________Actual__________ Blower Speeds Follow the steps below to change the blower speeds 1 Turn off electrical power to furnace 2 Remove blower access panel 3 Disconnect existing speed tap at control board speed terminal NOTE Termination of any unused motor leads must be insulated 4 Place unused blower speed tap on integrated control PARK terminal or insulate 5 Refer ...

Page 48: ... 10 1395 337 1270 256 1145 192 910 107 705 71 0 20 1365 344 1245 269 1100 199 865 115 655 76 0 30 1340 357 1215 275 1080 210 815 123 600 82 0 40 1305 367 1180 285 1040 219 760 133 550 93 0 50 1270 377 1145 296 1005 230 720 139 505 95 0 60 1250 393 1110 305 970 237 685 147 455 100 0 70 1210 401 1080 316 930 247 635 152 405 109 0 80 1185 412 1045 325 885 255 600 158 355 114 GUH92C090C3M Performance ...

Page 49: ...105 268 1015 229 875 184 0 80 1445 464 1230 332 1085 275 980 240 830 195 GUH92C110C4M Performance Less Filter External Static Pressure in w c Air Volume Watts at Various Blower Speeds High Medium High Medium Medium Low Low cfm Watts cfm Watts cfm Watts cfm Watts cfm Watts 0 10 1715 380 1495 262 1380 208 1295 176 1175 135 0 20 1680 391 1470 272 1355 220 1255 184 1135 145 0 30 1640 405 1425 284 1300...

Page 50: ...0 441 1715 353 1605 288 1435 210 2135 614 1885 421 1705 342 1595 280 1415 207 0 20 2085 648 1830 455 1665 362 1560 298 1360 220 2085 628 1830 437 1670 351 1545 293 1370 218 0 30 2040 663 1795 468 1630 374 1515 317 1325 229 2035 647 1790 451 1625 364 1500 308 1315 227 0 40 2005 675 1760 482 1585 386 1470 327 1270 244 1995 657 1755 469 1590 378 1460 319 1275 240 0 50 1965 688 1710 496 1540 399 1425 ...

Page 51: ...e Pipes Check the exhaust and air intake pipes and all connections for tightness and to make sure there is no blockage NOTE After any heavy snow ice or frozen fog event the furnace vent pipes may become restricted Always check the vent system and remove any snow or ice that may be obstructing the plastic intake or exhaust pipes Electrical 1 Check all wiring for loose connections 2 Check for the co...

Page 52: ... limit from the vestibule panel 20 Remove top cap screws to allow top cap to be tilted upward to allow clearance for removing heat exchanger 21 Remove two screws from the front cabinet flange at the blower deck Spread cabinet sides slightly to allow clearance for removal of heat exchanger 22 Remove screws along vestibule sides and bottom which secure vestibule panel and heat exchanger assembly to ...

Page 53: ... Reconnect wires to gas valve 44 Replace the blower compartment access panel 45 Refer to instruction on verifying gas and electrical connections when reestablishing supplies 46 Follow lighting instructions to light and operate furnace for 5 minutes to ensure that heat exchanger is clean and dry and that furnace is operating properly 47 Replace heating compartment access panel Cleaning the Burner A...

Page 54: ...roblems detected during the inspection may make it necessary to temporarily shut down the furnace until the items can be repaired or replaced Instruct the homeowners to pay attention to their furnace Situations can arise between annual furnace inspections that may result in unsafe operation For instance items innocently stored next to the furnace may obstruct the combustion air supply This could c...

Page 55: ...m height of eight 8 feet above grade directly in line with the exhaust vent terminal for the horizontally vented gas fueled heating appliance or equipment The sign shall read in print size no less than one half 1 2 inch in size GAS VENT DIRECTLY BELOW KEEP CLEAR OF ALL OBSTRUCTIONS 4 INSPECTION The state or local gas inspector of the side wall horizontally vented gas fueled equipment shall not app...

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