Page 1: Table Of Contents
INSTALLATION INSTRUCTIONS E 2010 Lennox Industries Inc. Dallas, Texas, USA G43UF MERIT SERIES GAS FURNACE UPFLOW AIR DISCHARGE 506497−01 03/2010 Supersedes 505,064M Litho U.S.A. THIS MANUAL MUST BE LEFT WITH THE HOMEOWNER FOR FUTURE REFERENCE This a safety alert symbol and should never be ignored.
Page 2: Unit Dimensions
1−15/16 (49) 5/8 (16) 23−1/2 3/4 (19) (597) 4−1/4 3/4 (19) *Bottom Return *Bottom Return (108) Air Opening Air Opening FRONT VIEW SIDE VIEW Model No. G43UF−24B−045 G43UF−24B−070 17−1/2 16−3/8 G43UF−36B−070 G43UF−36C−090 G43UF−36C−090H G43UF−48C−090 19−7/8 19−1/2 G43UF−48C−110 G43UF−48C−110H G43UF−60C−110 G43UF−60D−135 24−1/2 23−3/8...
Page 3: Parts Identification
Parts Arrangement G43UF PARTS IDENTIFICATION TOP CAP DuralokPlus HEAT EXCHANGER ASSEMBLY CABINET BURNER BOX ASSEMBLY GAS VALVE AND MANIFOLD FLUE COLLAR COMBUSTION AIR PRESSURE WARM HEADER PROVE SWITCH (COLLECTOR) COMBUSTION AIR INDUCER CONDENSER COIL BURNER PRIMARY LIMIT ACCESS PANEL COLD HEADER...
Page 4: Shipping And Packing List
G43UF−60C−110 units with 2" street elbow Y0162. Replace the provided 3" X 2" reducing elbow shipped with the The G43UF can be installed as either a Direct Vent or a G43UF−60D−135 units with 3" X 2" reducing elbow 40W22. Non−Direct Vent gas central furnace.
Page 5: Use Of Furnace As Constrction Heater
For installation in a residential garage, the furnace must be installed so that the burner(s) and the ignition source Lennox does not recommend the use of G43UF units as a are located no less than 18 inches (457 mm) above the construction heater during any phase of construction.
Page 6: General
In Canada, refer to the CSA B149 installation codes. Combustion, Dilution & Ventilation Air If the G43UF is installed as a Non−Direct Vent Furnace, CAUTION follow the guidelines in this section. NOTE − In Non−Direct Vent installations, combustion air Do not install the furnace in a corrosive or contami- is taken from indoors and flue gases are discharged out−...
Page 7 HAUST PIPE (ALTER- This space also includes adjacent rooms which are not NATE LOCATION) G43UF separated by a door. Though an area may appear to be un- confined, it might be necessary to bring in outdoor air for combustion if the structure does not provide enough air by NOTE −...
Page 8: Installation − Setting Equipment
TERMINATED (Ends 12" above VENTILATION TERMINATED EXHAUST PIPE bottom) LOUVERS EXHAUST PIPE (ALTERNATE G43UF INLET (For unheated (ALTERNATE LOCATION) G43UF crawl space) LOCATION) NOTE−The inlet and outlet air openings shall each have a free area of at least one square inch per 4,000 Btu (645mm per 1.17kW) per hour...
Page 9 The G43UF gas furnace can be installed as shipped in WARNING the upflow position only. Refer to figure 8 for clearances. Select a location that allows for the required clearances Improper installation of the furnace can result in per- that are listed on the unit nameplate. Also consider gas sonal injury or death.
Page 10 5 − Return air from bottom and one side. Plenum Refer to Engineering Handbook for additional information. G43UF applications which include side return air and a condensate trap installed on the same side of the cabi- net require either a return air base or field−fabricated...
Page 11: Filters
Leveling an Upflow Unit Removing the Bottom Panel When the side return air inlets are used in an upflow ap- plication, it may be necessary to install leveling bolts on the bottom of the furnace. Use field−supplied corrosion−resist- ant 5/16 inch machine bolts (4) and nuts (8). See figure 12. NOTE −...
Page 12: Pipe & Fittings Specifications
Table 3 lists the available exhaust termination kits, as well as vent pipe equivalencies which must be used when siz- ing vent pipe. All Lennox vent terminations are PVC. Page 12...
Page 13 ***For use only in non−direct vent applications, when snow riser is which must be installed on the exhaust outlet when this kit is used not required. Requires field−provided and installed 2" exhaust ac- with the G43UF−24B−045, G43UF−24B−070 and G43UF−36B−070 celerator. furnaces.
Page 14: Vent Piping Guidelines
***G43UF−60D−135 must have 3" to 2" reducing ell (supplied or field replace- termination, in spite of the 12−inch vertical offset. ment Canadian kit) installed directly into unit flue collar.
Page 15: Joint Cementing Procedure
Joint Cementing Procedure Venting Practices The thickness of construction through which vent pipes All cementing of joints should be done according to the may be installed is 24" (610mm) maximum and 3/4" specifications outlined in ASTM D 2855. (19mm) minimum. 1 −...
Page 16 TYPICAL EXHAUST PIPE CONNECTIONS AND CONDENSATE TRAP INSTALLATION IN UPFLOW DIRECT OR NON−DIRECT VENT APPLICATIONS (Right−Hand Exit) 45° 45° 2−1/2", 3", OR 4" 2" TRANSITION 2" −045, −070, or −090 with 2" VENT PLUG 2" 2−1/2", 3", or 4" −110 with 2" SIDE VIEW (Must be 2"...
Page 17 The G43UF furnace may be installed in either direct vent or non−direct vent applications. In non−direct vent ap- Refer to figure 16 for pipe sizes.
Page 18 In Direct Vent applications, combustion air is taken from outdoors and the flue gases are discharged to the out- IMPORTANT doors. The G43UF is then classified as a direct vent, Cate- Do not use screens or perforated metal in exhaust gory IV gas furnace.
Page 19: Vent Termination Clearances
‡ Permitted only if veranda, porch, deck or balcony is fully open on a minimum of two sides beneath the floor. Lennox recommends avoiding this location if possible. FIGURE 18 Page 19...
Page 20 ‡ Permitted only if veranda, porch, deck or balcony is fully open on a minimum of two sides beneath the floor. Lennox recommends avoiding this location if possible. FIGURE 19 Page 20...
Page 21 Details of Intake and Exhaust Piping Terminations for FIELD SUPPLIED WALL TERMINATION OR Direct Vent Installation (15F74) WALL RING TERMINATION KIT NOTE − In Direct Vent installations, combustion air is tak- en from outdoors and flue gases are discharged to out- NOTE −...
Page 22 TABLE 6 FIELD SUPPLIED WALL TERMINATION OR EXHAUST PIPE TERMINATION SIZE REDUCTION (15F74) WALL RING TERMINATION KIT G43UF Termination With INTAKE ELBOW Exhaust Pipe Size MODEL Pipe Size 1−1/2" (38mm) 045 and 070 NOTE − FIELD PROVIDED 2" (51mm), 2−1/2" (64mm), 2"...
Page 23 1 1/2" (38mm) accelerator EXHAUST VENT Front View provided on 71M80 & 44W92 kits for SIZE G43UF−24B−045, 070 & TERMINATION 36B−070 PIPE PER INTAKE FLASHING TABLE 6. 12” (305mm) (Not Furnished) INTAKE Minimum Above Average Snow Accumulation Top View 1/2" (13mm) Foam Insulation...
Page 24 WALL TERMINATION KITS (CLOSE−COUPLE) EXTENDED VENT FOR GRADE CLEARANCE 2 inch (51 mm) 22G44 (US) 3 inch (76 mm) 44J40 (US) If Intake and Exhaust Pipe is less than 12 in. (305 mm) above snow accumulation or other obstructions, FIELD−PROVIDED field fabricated piping must be installed.
Page 25 G43MP DIRECT VENT APPLICATION SIZE TERMINATION STRAIGHT−CUT OR USING EXISTING CHIMNEY ANGLE−CUT IN DIRECTION PIPE PER TABLE 6. OF ROOF SLOPE * 12" (305mm) ABOVE AVE. SNOW 1/2" (13mm) FOAM 3" − 8" EXHAUST VENT ACCUMULATION (76mm− INSULATION 8" − 12" 1/2"...
Page 26 24" but less than 48". same side as the condensate trap, filter rack FIGURE 33 must be installed beyond condensate trap to avoid interference. G43UF NON−DIRECT VENT APPLICATION USING EXISTING CHIMNEY FIGURE 35 SIZE TERMINATION STRAIGHT−CUT OR ANGLE−CUT IN DIRECTION PIPE PER TABLE 6.
Page 27: Gas Piping
3 − Gas piping must not run in or through air ducts, clothes Heating cable kit is available from Lennox in various chutes, chimneys or gas vents, dumb waiters or eleva- lengths;...
Page 28 4 − Piping should be sloped 1/4 inch per 15 feet (6mm per Leak Check 5.6m) upward toward the gas meter from the furnace. After gas piping is completed, carefully check all piping The piping must be supported at proper intervals, ev- connections (factory−...
Page 29 TABLE 7 GAS PIPE CAPACITY − FT /HR (kL/HR) Length of Pipe−Feet(m) Nominal Internal Iron Pipe Size Diameter −Inches(mm) −Inches(mm) (3.048) (6.096) (9.144) (12.192) (15.240) (18.288) (21.336) (24.384) (27.432) (30.480) .364 (6.35) (9.246) (1.13) (.82) (.68) (.57) (.51) (.45) (.42) (.40) (.37) (.34)
Page 30: Electrical
FIGURE 39 standard C22.1) for Canada. A green ground wire is INTERIOR MAKE−UP BOX INSTALLATION provided in the field make−up box. NOTE − The G43UF furnace contains electronic com- MAKE−UP ponents that are polarity sensitive. Make sure that the Left side furnace is wired correctly and is properly grounded.
Page 31 CONDENSING UNIT COOLING when there is no cooling or heating demand. INDOOR BLOWER 2 − When the G43UF is running in the heating mode, the CONDENSING COMMON UNIT COMMON indoor blower will run on the heating speed. 3 − When there is a cooling demand, the indoor blower will FIGURE 41 run on the cooling speed.
Page 32 TYPICAL G43UF WIRING DIAGRAM FIGURE 43 Page 32...
Page 33: Unit Start−Up
INTEGRATED CONTROL BOARD (Automatic Hot Surface Ignition System) TERMINAL DESIGNATIONS Humidifier (120VAC) LINE Input (120VAC) XFMR Transformer (120VAC) Electronic Air Cleaner (120VAC) COOL Blower − Cooling Speed (120VAC) HEAT Blower − Heating Speed (120VAC) PARK Dead terminals to park alternate spd taps FLAME Flame senser NEUTRALS...
Page 34 White Rodgers 36G Series Gas Valve floor. OUTLET PRESSURE The gas valve on the G43UF is equipped with a gas con- POST trol switch (lever). Use only your hand to move switch. Never use tools. If the the switch will not move by hand, do not try to repair it.
Page 35: Gas Pressure Adjustment
Heat". Heating sequence then restarts at step 1. tive burner box must be considered. Use pressure test Gas Pressure Adjustment adapter kit (available as Lennox part 10L34) to assist in measurement. Gas Flow (Approximate) 1 − Remove the threaded plug from the outlet side of the 1 −...
Page 36: High Altitude Information
High Altitude Information NOTE − In Canada, certification for installations at eleva- TABLE 9 tions over 4500 feet (1372 m) is the jurisdiction of local au- Manifold Pressure (Outlet) inches w.c. thorities. Altitude (feet) Model The manifold pressure may require adjustment to ensure Fuel Input 0−...
Page 37: Testing For Venting And Combustion Air
Do not operate a summer exhaust fan. After the G43UF gas furnace has been started, the follow- 6 − Follow the lighting instruction to place the appliance ing test should be conducted to ensure proper venting and being inspected into operation.
Page 38: Other Unit Adjustments
Electrical Other Unit Adjustments 1 − Check all wiring for loose connections. Primary Limit 2 − Check for the correct voltage at the furnace (furnace operating). The primary limit is located on the heating compartment 3 − Check amp-draw on the blower motor. vestibule panel.
Page 39: Blower Performance Data
Blower Motor Performance G43UF−24B−045 PERFORMANCE (Less Filter) G43UF−24B−070 PERFORMANCE (Less Filter) Air Volume / Watts at Different Blower Speeds Air Volume / Watts at Different Blower Speeds External External Medium− Medium− Medium− Medium− Static Static High High High High Pressure Pressure in.
Page 40 G43UF−60C−110 PERFORMANCE (Less Filter) External Bottom Return Air, Side Return Air with Optional RAB Single Side Return Air − Air volumes in bold require field Return Air Base, Return Air from Both Sides or Return fabricated transition to accommodate 20 x 25 x 1 in. air Static Air from Bottom and One Side.
Page 41: Service
11 − Disconnect condensate drain tubing from flue collar. Filters Remove screws that secure both flue collars into All G43UF filters are installed external to the unit. Filters place. Remove flue collars. It may be necessary to cut should be inspected monthly. Clean or replace the filters the exiting exhaust pipe for removal of the fittings.
Page 42 19 − Remove screws along vestibule sides and bottom 38 − Secure burner box assembly to vestibule panel using which secure vestibule panel and heat exchanger as- four existing screws. Make sure burners line up in sembly to cabinet. Remove two screws from blower center of burner ports.
Page 43: Planned Service
Return air duct − Must be properly attached and provide Planned Service an air seal to the unit. A service technician should check the following items dur- Operating performance − Unit must be observed during ing an annual inspection. Power to the unit must be shut off operation to monitor proper performance of the unit and the for safety.
Page 44: Troubleshooting
Troubleshooting: Heating Sequence of Operation HEATING SEQUENCE OF OPERATION ABNORMAL HEATING MODE NORMAL HEATING MODE POWER ON GAS VALVE OFF. COMBUSTION AIR INDUCER OFF. INDOOR BLOWER DELAY OFF. CONTROL SELF−CHECK OKAY? LED #1 ON LED #2 ON (RESET CONTROL BY TURNING MAIN POWER OFF.) POLARITY REVERSED.
Page 45 Troubleshooting: Heating Sequence of Operation (Continued) HEATING SEQUENCE CONTINUED NORMAL HEATING MODE ABNORMAL HEATING MODE 15-SECOND COMBUSTION AIR INDUCER PREPURGE INITIATED BY CLOSED PRESSURE SWITCH. LEDS SIGNAL ALTERNATING FAST FLASH UNTIL IGNITOR WARM-UP −− 20 SECONDS. IS VOLTAGE ABOVE 90 VOLTS? VOLTAGE IS ABOVE 95 VOLTS, THEN RESTARTS HEATING...
Page 46: Troubleshooting: Cooling Sequence Of Operation
Troubleshooting: Cooling Sequence of Operation COOLING SEQUENCE OF OPERATION NORMAL COOLING MODE ABNORMAL COOLING MODE POWER ON IGNITION CONTROL MAIN POWER ON. GAS VALVE OFF. COMBUSTION AIR INDUCER OFF. INDOOR BLOWER OFF WITH NORMAL DELAY. CONTROL SELF DIAGNOSTIC CHECK. SIGNAL CIRCUIT BOARD FAILURE AT LED. IS CONTROL OPERATING NORMALLY? INTERRUPT MAIN POWER TO RESET CONTROL.
Page 47: Repair Parts List
The following repair parts are available through Lennox dealers. When ordering parts, include the complete furnace model number listed on the CSA nameplate −− Example: G43UF−24B−045−3. All service must be performed by a licensed pro- fessional installer (or equivalent), service agency, or gas supplier.
Page 48: Vent Pipe Sizing Worksheet
Vent Pipe Sizing Worksheet Step 1 Proposed vent pipe size : ______ Equivalent Feet Step 2 Termination kit catalog number : _____________ Vent pipe equivalency value from table 3 : ______ Step 3 Total number of 90° elbows required (indoors and outdoors) ______ X 5 = ______ equivalent feet of pipe Step 4 Total number of 45°...
Page 49: Start−Up & Performance Check List
Start−Up & Performance Check List UNIT SET UP Furnace: Model Number_______________ Serial Number_________________ SUPPLY Line Voltage GAS SUPPLY LP Propane Gas Natural Gas Piping Connections Tight Leak Tested Flter Supply Line Pressure W.C.________ RETURN AIR Gas Supply Pressure DUCT SYSTEM SUPPLY AIR DUCT Sealed Insulated (if necessary)
Page 50 UNIT OPERATION HEATING MODE COOLING MODE GAS MANIFOLD PRESSURE W.C._____ INDOOR BLOWER AMPS______ COMBUSTION SAMPLE CO CO PPM_______ TEMPERATURE DROP ______ Return Duct Temperature _________ INDOOR BLOWER AMPS______ Supply Duct Temperature _______ Temperature Drop = _________ TEMPERATURE RISE TOTAL DUCT STATIC (dry coil) Supply Duct Temperature ________ Total Static = ________ Return Duct Temperature...
Page 51 Requirements for Commonwealth of Massachusetts Modifications to NFPA−54, Chapter 10 4 − 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 re- shall not approve the installation unless, upon inspec- quirements: tion, the inspector observes carbon monoxide detec- For all side wall, horizontally vented, gas−fueled equipment...

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