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507867-02

Page 42 of 55

Issue 1933

Figure 68. Integrated Control

(Automatic Hot Surface Ignition System)

Terminal Designations

120 HUM

Humidifier (120 VAC)

LINE

Input (120 VAC)

XFMR

Transformer (120 VAC)

CIRC

Indoor Blower (120 VAC)

EAC

Electronic Air Cleaner (120 VAC)

COOL

Blower - Cooling Speed (24 VAC)

HEAT

Blower - Heating Speed (24 VAC)

FAN

Blower - Fan Speed (24 VAC)

PARK

Dead terminals to park all speed taps

NEUTRALS

Neutral Terminals (120 VAC)

FS

Flame Sense

24 COM

Common (24 VAC)

HUM 24

Humidifier (24 VAC)

Unit Start-Up

FOR YOUR SAFETY READ BEFORE OPERATING

Do not use this furnace if any part has been underwater. 

A  flood-damaged  furnace  is  extremely  dangerous. 

Attempts to use the furnace can result in fire or explosion. 

Immediately call a qualified service technician to inspect 

the  furnace  and  to  replace  all  gas  controls,  control 

system parts, and electrical parts that have been wet or 

to replace the furnace, if deemed necessary.

 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

BEFORE LIGHTING

 the unit, smell all around the furnace 

area for gas. Be sure to smell next to the floor because 

some gas is heavier than air and will settle on the floor.

The gas valve on the unit is equipped with a gas control 

switch (lever). Use only your hand to move switch. Never 

use tools. If the switch will not move by hand, do not try to 

repair it. Force or attempted repair may result in a fire or 

explosion.

Placing the Furnace into Operation

This  furnace  is  equipped  with  an  automatic  hot  surface 

ignition system. Do not attempt to manually light burners 

on this furnace. Each time the thermostat calls for heat, the 

burners will automatically light. The ignitor does not get hot 

when there is no call for heat on these units.

Summary of Contents for BG921-E

Page 1: ...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 person...

Page 2: ...ide 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 E...

Page 3: ...lve 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...

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 a...

Page 5: ...rnace 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 furnac...

Page 6: ...ALL 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 pi...

Page 7: ...ion 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...

Page 8: ...e 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 commun...

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 l...

Page 10: ...ace 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 re...

Page 11: ...ng 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...

Page 12: ...ion 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...

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...

Page 14: ...t 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...

Page 15: ...et 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 Accel...

Page 16: ...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 remain...

Page 17: ...al 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...

Page 18: ...ck the terminations IMPORTANT Use Figure 24 to correctly size vent pipe diameter 030 045 070 090 110 Standard or Concentric See Table 3 Intake or Exhaust 1 1 2 2 2 1 2 or 3 Furnace capacity 1 Which te...

Page 19: ...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 Capacit...

Page 20: ...50 18 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...

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...

Page 22: ...ntake 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 23: ...se 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...

Page 24: ...N A 25 N A N A N A N A N A 2 in N A N A 18 16 31 28 50 48 30 30 2 1 2 in N A N A 13 N A 24 N A 42 N A 56 N A 3 in N A N A 9 9 18 18 35 35 47 47 20 to 1 7 to 17 1 1 2 in N A N A 15 N A 20 N A N A N A N...

Page 25: ...arance 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...

Page 26: ...s 152mm 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 Btu...

Page 27: ...tallation 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...

Page 28: ...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 terminatio...

Page 29: ...D 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...

Page 30: ...d 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...

Page 31: ...XHAUST 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 TER...

Page 32: ...ermination 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...

Page 33: ...ittings 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 D...

Page 34: ...iping 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 do...

Page 35: ...507867 02 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 pi...

Page 37: ...ted 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...

Page 38: ...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 50...

Page 39: ...wer 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 C...

Page 40: ...ously 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...

Page 41: ...507867 02 Page 41 of 55 Issue 1933 Figure 67 Typical Wiring Diagram...

Page 42: ...ARNING 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...

Page 43: ...r 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 fo...

Page 44: ...bilize 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 va...

Page 45: ...s installation 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 Capac...

Page 46: ...d 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 e...

Page 47: ...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 ex...

Page 48: ...0 1390 348 1270 271 1135 199 885 109 735 71 0 20 1355 349 1230 280 1100 207 850 119 680 81 0 30 1330 368 1205 291 1060 220 795 126 625 84 0 40 1295 378 1180 298 1025 226 755 134 570 91 0 50 1265 386 1...

Page 49: ...06 1275 173 1160 135 0 20 1655 392 1460 273 1315 219 1230 185 1110 142 0 30 1615 408 1410 282 1290 225 1195 192 1065 151 0 40 1595 416 1365 295 1245 236 1155 203 1010 160 0 50 1560 429 1335 308 1200 2...

Page 50: ...33 1880 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 46...

Page 51: ...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 ven...

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 bl...

Page 53: ...econnect 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 instructi...

Page 54: ...s Problems 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 furna...

Page 55: ...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...

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