Page 1: Table Of Contents
Be careful when you handle this equipment. NOTICE A thermostat is not included and must be ordered HORIZONTAL RIGHT HORIZONTAL LEFT separately. D The Lennox icomfort Touch™ thermostat must be DOWNFLOW UPFLOW used in communicating applications. D In non−communicating applications, the Lennox ®...
Page 2: Unit Dimensions
G71MPP Unit Dimensions − inches (mm) NOTE − 60C and 60D size units that require air volumes over 1800 cfm (850 L/s) must have one of the following: a. Single side return air with transition, to accommodate 20 x 25 x 1 in. (508 x 635 x 25 mm) air filter. Required to SUPPLY AIR maintain proper air velocity.
Page 3: Figure
G71MPP Parts Arrangement BAG ASSEMBLIES (shipping location) HEAT EXCHANGER BURNER BOX ASSEMBLY WARM HEADER VARIABLE CAPACITY (COLLECTOR BOX) GAS VALVE CONDENSER COIL PRESSURE SWITCH COMBUSTION AIR ASSEMBLY WITH PRESSURE PRESSURE SWITCHES CONDITIONING DEVICE COLD HEADER VARIABLE SPEED (COLLECTOR BOX) COMBUSTION AIR INDUCER...
Page 4: Shipping And Packing List
A conversion kit (ordered separately) is re- quired for use in propane/LP gas applications. damage, immediately contact the last carrier. The G71MPP can be installed only as a Direct Vent gas The following items may also be ordered separately: central furnace.
Page 5: Use Of Furnace As Construction Heater
This G71MPP furnace may be used as a high−static unit heater. The G71MPP may also be installed in an aircraft Lennox does not recommend the use of G71MPP units as hangar in accordance with the Standard for Aircraft Han- a construction heater during any phase of construction.
Page 6: General
CAUTION supply connections, electrical supply, vent connection, condensate trap and drain connections, and installation G71MPP unit should not be installed in areas normal- and service clearances [24 inches (610 mm) at unit ly subject to freezing temperatures. front]. The unit must be level from side to side. The unit These instructions are intended as a general guide and do may be tilted slightly (maximum 1/2 in.) from back to...
Page 7 NOTE − G71MPP−36B and −36C units with 1/2 hp blower Installation Clearances motors are equipped with three flexible legs and one rigid leg. The rigid leg is equipped with a shipping bolt and a flat white plastic washer (rather than the rubber mounting grommet used with a flexible mounting leg).
Page 8 G71MPP applications which include side return air and 2 − Return air from single side with optional RAB Return Air Base. See figure 7. a condensate trap installed on the same side of the cabinet require either a return air base or field−fabri- 3 −...
Page 9 Setting an Upflow Unit Downflow Application Installation Clearances When the side return air inlets are used in an upflow ap- plication, it may be necessary to install shims on the bottom of the furnace. If desired, use field−supplied corrosion−re- sistant 5/16 inch machine bolts (4) and nuts (8) to level the furnace.
Page 10 3 − In all cases, plenum should be secured to top of fur- 11M62 25 − 3/4 (24.5") nace using sheet metal screws. 4 − Make certain that an adequate seal is made. G71MPP UNIT PLENUM SECURE FROM (Field Provided) OUTSIDE CABINET SUPPLY AIR PLENUM PROPERLY É...
Page 11 4 − Using 3/8 inch rods and support frame kit or field−fabri- cated supports, fabricate suspension hangers, keep- The G71MPP may also be installed as a unit heater. Either suspend the furnace as shown in figure 14, or install the ing in mind front service access clearances.
Page 12: Filters
Filters G71MPP Installed in Unit Heater Applications The G71MPP may also be installed as a unit heater. Either This unit is not equipped with a filter or rack. A field−pro- suspend the furnace from roof rafters or floor joists, as vided filter is required for the unit to operate properly.
Page 13: Table
dards. The solvent shall be free flowing and contain no Duct System lumps, undissolved particles or any foreign matter that ad- Use industry-approved standards to size and install the versely affects the joint strength or chemical resistance of supply and return air duct system. This will result in a quiet the cement.
Page 14 Table 5 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. TABLE 5 OUTDOOR TERMINATION KITS AND CORRESPONDING EQUIVALENCIES...
Page 15: 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 5 : ______ Step 3 Total number of 90° elbows required (indoors and outdoors) ______ X 5 = ______ equivalent feet of pipe Step 4 Total number of 45°...
Page 16: Figure
Vent Piping Guidelines The G71MPP can be installed only as a Direct Vent gas Terminations should be used. Exhaust vent termination central furnace. pipe is sized to optimize the velocity of the exhaust gas as it exits the termination. Refer to table 8.
Page 17: Joint Cementing Procedure
5. nadian kit) installed directly into unit flue collar. **G71MPP−60D−135 must have 3" to 2" reducing ell (supplied or field replace- 2 − Determine the number of 90° elbows required for both ment Canadian kit) installed directly into unit flue collar.
Page 18: Venting Practices
The thickness of construction through which vent pipes may be installed is 24" (610mm) maximum and 3/4" IMPORTANT (19mm) minimum. If a G71MPP furnace replaces a furnace which was commonly vented with another gas appliance, Exhaust piping and condensate trap must be...
Page 19 FIGURE 19 Intake Piping TYPICAL EXHAUST PIPE CONNECTIONS HORIZONTAL DIRECT VENT APPLICATIONS The G71MPP furnace may be installed only in direct vent (Horizontal Right−Hand Air Discharge Application Shown) applications. The G71MPP unit is designed for either left−side or right− side air intake connections in either upflow or downflow ap- −36B−070...
Page 20 −36C−090 −36C−090 −60C−090 −60C−090 −60C−090 −60C−110 −60C−110 −60D−135* *Limit pipe length to 4" in G71MPP−135 applications. FIGURE 21 TYPICAL AIR INTAKE PIPE CONNECTIONS HORIZONTAL DIRECT VENT APPLICATIONS (Horizontal Right−Hand Air Discharge Application Shown) −36B−070 2−1/2”, *Limit pipe −36C−090 3” OR 4”...
Page 21: 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 23 Page 21...
Page 22 In at- TABLE 8 tic or closet installations, vertical termination through the EXHAUST PIPE TERMINATION SIZE REDUCTION roof is preferred. Figures 25 through 32 show typical ter- G71MPP minations. Exhaust Pipe Size Termination Pipe Size MODEL 1 −...
Page 23: Front
12" (305) MAX. for 2" (51) 3(76) MAX. Inches(mm) SIZE TERMINATION (unless supported) Inches(mm) PIPE PER TABLE 8. UNCONDITIONED SPACE UNCONDITIONED 8 (203) ATTIC SPACE OUTSIDE WALL 8" (203) MIN MIN. 1/2" (13) FOAM SIZE INSULATION IN PROVIDE SUPPORT TERMINATION UNCONDITIONED 12"...
Page 24 INSTALLATION OF DIRECT VENT WALL TERMINATION KIT (30G28) FIGURE 31 Horizontal Horizontal left and right and optional optional downflow downflow G71MPP DIRECT VENT APPLICATION STRAIGHT−CUT OR USING EXISTING CHIMNEY ANGLE−CUT IN DIRECTION OF ROOF SLOPE * Optional Optional 3" − 8" EXHAUST VENT (76mm−...
Page 25 Use provided sheet Heating cable kit is available from Lennox in various metal screw to secure bottom trap flange to side of lengths;...
Page 26: Gas Piping
Gas Piping IMPORTANT CAUTION Compounds used on threaded joints of gas piping must be resistant to the actions of liquified petro- If a flexible gas connector is required or allowed by leum gases. the authority that has jurisdiction, black iron pipe shall be installed at the gas valve and extend outside the furnace cabinet.
Page 27 Horizontal Applications Possible Gas Piping Configurations MANUAL MAIN SHUT−OFF Horizontal Application VALVE Left−Side Air Discharge MANUAL MAIN SHUT−OFF VALVE GROUND JOINT UNION GROUND JOINT DRIP LEG UNION DRIP LEG Horizontal Application MANUAL Right−Side Air Discharge MAIN SHUT−OFF VALVE GROUND JOINT UNION DRIP LEG FIGURE 37...
Page 28: Electrical
FIGURE 38 NOTE − Do NOT make a wire connection between the room thermostat L terminal and the L terminal of the G71MPP integrated control unless this is a INTERIOR MAKE−UP BOX INSTALLATION communicating thermostat installation with a non− communicating outdoor unit.
Page 29 10 ft. when switches 6 and 7. wired with 18−gauge thermostat wire. 2 − When the G71MPP is running in the heating mode, the NOTE − Wiring distance between the furnace and the out- integrated control will automatically adjust the blower door air sensor should not exceed 200ft.
Page 30 Toucht Communicating Unit icomfort Toucht Communicating Systems non−Communicating Outdoor Unit icomfort Toucht Thermostat icomfort Toucht Thermostat icomfortt Enabled G71MPP Indoor Furnace icomfortt Enabled G71MPP Indoor Furnace icomfortt Outdoor Air Conditioner or Heat Pump Standard Outdoor Air Conditioner icomfortt ENABLED...
Page 31 Optional Accessories for use with any icomfortt System icomfortt NOTE: icomfortt T’STAT SENSES HUMIDITY & CONTROLS 24V ENABLED H" OUTPUT (& 120V H" OUTPUT) TO CYCLE HUMIDIFIER G71MPP BASED ON DEMAND. NO OTHER CONTROL OR HUMIDISTAT FURNACE REQUIRED. OPTIONAL OUTDOOR AIR SENSOR FOR USE WITH HU- MIDIFIER (IF NOT ALREADY IN THE SYSTEM FOR OTHER FUNCTIONS.
Page 32 TABLE 10 Field Wiring for Non−Communicating Thermostat Applications DIP Switch Settings and On−Board Links (figure 44) W914 W915 (DS to R) W951 (Y1 to Y2) Dehumidifi- Thermostat Wiring Connections DIP Switch 1 (O to R) Two−Stage cation or Heat Pumps Cooling Harmony IIIt...
Page 33 TABLE 10 Field Wiring for Non−Communicating Thermostat Applications (Continued) DIP Switch Settings and On−Board Links (figure 44) W914 W915 (DS to R) (Y1 to Y2) W951 Dehumidifi- Thermostat Wiring Connections DIP Switch 1 Two−Stage (O to R) cation or Cooling Heat Pumps Harmony IIIt...
Page 34 * Connect W1 to W1 ONLY if using defrost tempering kit 67M41 NOTE − Do NOT make a wire connection between the room thermostat L terminal and the L terminal of the G71MPP integrated control. Page 34...
Page 35 TYPICAL G71MPP WIRING DIAGRAM FIGURE 43 Page 35...
Page 36: Integrated Control
Integrated Control INTEGRATED CONTROL NEUTRAL TERMINALS COMBUSTION AIR INDUCER CONNECTOR IGNITOR CONNECTOR DIAGNOSTIC LINE VOLTAGE PUSH BUTTON TERMINALS FLAME SENSE DIP SWITCHES OUTDOOR AIR INDOOR SENSOR BLOWER TERMINALS 7−SEGMENT CONNECTOR DIAGNOSTIC LED DISCHARGE AIR ON−BOARD SENSOR LINKS TERMINALS W915 W951 W914 FACTORY TEST HEADER PINS.
Page 37 10 minutes fixed Two−Stage Heat (W1 70%, W2 100%) Two−Stage G71MPP units are equipped with a variable−capacity, vari- off delay affects comfort and is adjustable to satisfy individ- able−speed integrated control. This control manages igni- ual applications. Adjust the blower off delay to achieve a tion timing, combustion air inducer speed, heating mode supply air temperature between 90°...
Page 38 Switches 8 and 9 −− Cooling Mode Blower Speed −− TABLE 16 Cooling Mode Blower Speed Ramping Switches 8 and 9 are used to select cooling blower motor Ramping Option Switch 12 Switch 13 speed. The unit is shipped from the factory with the DIP A (Factory) switches positioned for high speed (4) indoor blower motor operation during the cooling mode.
Page 39 Refer to table 19 for operation sequence in ap- form the high−fire and low−fire pressure switch calibra- plications including G71MPP, a thermostat which features tions and display CAL". After calibration, the LED will humidity control and a single−speed outdoor unit. Table 20 return to the flashing −"...
Page 40 G71MPP INTEGRATED CONTROL CONFIGURATION GUIDE FIGURE 45 Page 40...
Page 41 TABLE 19 OPERATING SEQUENCE G71MPP, ComfortSenset 7000 Thermostat and Single−Stage Outdoor Unit OPERATING SYSTEM DEMAND SYSTEM RESPONSE SEQUENCE Thermostat Demand Relative Humidity Blower System Step Compressor Comments Condition Status (COOL) NO CALL FOR DEHUMIDIFICATION Compressor and in- Normal Operation Acceptable...
Page 42 TABLE 20 OPERATING SEQUENCE G71MPP, ComfortSenset 7000 Thermostat and Two−Stage Outdoor Unit OPERATING SYSTEM DEMAND SYSTEM RESPONSE SEQUENCE Thermostat Demand Relative Humidity Blower System Step Compressor Comments Condition Status (COOL) NO CALL FOR DEHUMIDIFICATION Normal Operation − Acceptable Compressor and indoor blower follow thermostat Normal Operation −...
Page 43: Blower Motor Performance
1105 The effect of static pressure is included in air volumes shown. Lennox Harmony IIIt Zone Control Applications − Minimum blower speed is 300 cfm. The following control configurations are available. See Installation Instructions for details and DIP switch settings.
Page 44 1100 The effect of static pressure is included in air volumes shown. Lennox Harmony IIIt Zone Control Applications − Minimum blower speed is 300 cfm. The following control configurations are available. See Installation Instructions for details and DIP switch settings.
Page 45 1755 The effect of static pressure is included in air volumes shown. Lennox Harmony IIIt Zone Control Applications − Minimum blower speed is 400 cfm. The following control configurations are available. See Installation Instructions for details and DIP switch settings.
Page 46 1735 The effect of static pressure is included in air volumes shown. Lennox Harmony IIIt Zone Control Applications − Minimum blower speed is 400 cfm. The following control configurations are available. See Installation Instructions for details and DIP switch settings.
Page 47 TABLE 25 G71MPP−60C−090 BLOWER PERFORMANCE (less filter) −− Side Return Air with Optional RAB Return Air Base 0 through 0.80 in. w.g. External Static Pressure Range HEATING BLOWER PERFORMANCE Heating Input Range and Blower Volume − CFM Heating Adjust CFM Selections...
Page 48 1790 The effect of static pressure is included in air volumes shown. Lennox Harmony IIIt Zone Control Applications − Minimum blower speed is 475 cfm. The following control configurations are available. See Installation Instructions for details and DIP switch settings.
Page 49 1755 The effect of static pressure is included in air volumes shown. Lennox Harmony IIIt Zone Control Applications − Minimum blower speed is 475 cfm. The following control configurations are available. See Installation Instructions for details and DIP switch settings.
Page 50 Continuous Fan speeds are approximately 28%, 38%, 70% and 100% (DIP switch selectable) of the same second−stage COOL speed position minimum 450 cfm. G71MPP−60C−110 BLOWER MOTOR WATTS − COOLING − Side Return Air with Optional RAB Return Air Base Motor Watts @ Various External Static Pressures − in. wg.
Page 51 1780 The effect of static pressure is included in air volumes shown. Lennox Harmony IIIt Zone Control Applications − Minimum blower speed is 475 cfm. The following control configurations are available. See Installation Instructions for details and DIP switch settings.
Page 52 1755 The effect of static pressure is included in air volumes shown. Lennox Harmony IIIt Zone Control Applications − Minimum blower speed is 475 cfm. The following control configurations are available. See Installation Instructions for details and DIP switch settings.
Page 53 Continuous Fan speeds are approximately 28%, 38%, 70% and 100% (DIP switch selectable) of the same second−stage COOL speed position minimum 450 cfm. G71MPP−60D−135 BLOWER MOTOR WATTS − COOLING − Side Return Air with Optional RAB Return Air Base Motor Watts @ Various External Static Pressures − in. wg.
Page 54: Unit Start−Up
WARNING The gas valve on the G71MPP is equipped with a gas control switch. Use only your hand to move the control Do not use this furnace if any part has been under- switch.
Page 55: Gas Pressure Measurement
1/2 cu ft Dial 1 cu ft Dial tive burner box must be considered. Use pressure test adapter kit (available as Lennox part 10L34) to assist in measurement. 1 − Remove the threaded plug from the outlet side of the gas valve and install a field−provided barbed fitting.
Page 56: Back
The gas valve should not be adjusted. thorities. The combustion air pressure switch is factory−set and re- G71MPP units require no manifold pressure adjustments quires no adjustment. for operation at altitudes up to 10,000 feet (3048m) above sea level. Units installed at altitude of 7,501 to 10,000 feet NOTE −...
Page 57: Ends
Failure To Operate stabilization delay expires, the inducer speed is ad- justed to the appropriate target rate. The inducer will If the unit fails to operate, check the following: remain at the 70 percent speed as long as the thermo- 1 −...
Page 58: Service
5 − If second−stage heat is required, the thermostat sec- 5 − If the heating demand continues beyond the second− ond−stage heat contacts close and send a signal to the stage on delay, the integrated control energizes the integrated control. The integrated control either in- combustion air inducer at 70 percent speed.
Page 59: Vent
10 − Disconnect condensate drain line from the conden- sate trap. Remove condensate trap (it may be neces- All G71MPP filters are installed external to the unit. Filters sary to cut drain pipe). Remove screws that secure should be inspected monthly. Clean or replace the filters condensate collars to either side of the furnace and re- when necessary to ensure proper furnace operation.
Page 60: Planned Service
NOTE − G71MPP−135 units are secured to the vesti- bule panel by two additional screws. These screws Instruct the homeowners to pay attention to their must be removed for servicing;...
Page 61: Integrated Control Diagnostic Codes
Integrated Control Diagnostic Codes Press the diagnostic push button and hold it to cycle through a menu of options. Every five seconds a new menu item will be displayed. Release the button when the desired mode is displayed. When a solid "P" is displayed, the furnace capacity/ size is programmed. When the solid E"...
Page 62 Integrated Control Diagnostic Codes (continued) Code Diagnostic Codes/Status of Equipment Action Required to Clear and Recover E 223 Low pressure switch failed open − Refer to troubleshooting in installation Check inches of water column pressure during operation of instruction. low pressure switch on heat call, measure inches of water column of operating pressure, inspect vent and combustion air inducer for correct operation and restriction.
Page 63 Integrated Control Diagnostic Codes (continued) Code Diagnostic Codes/Status of Equipment Action Required to Clear and Recover E 295 Indoor blower motor temperature is too high. Indoor blower motor over temperature (motor tripped on internal protector), Check motor bearings, amperes. Replace if necessary. E 310 Discharge error sensor failure −...
Page 64: Configuring Unit Size Codes
UNIT SIZE alarm present, CODE FURNACE MODEL furnace control will G71MPP−36B−070 display error code, if G71MPP−36C−090 alarm is not present solid dash starts blinking on G71MPP−60C−090 7−segment LED display G71MPP−60C−110 G71MPP−60D−135 Push and hold button until the solid P symbol is displayed on the 7−segment...
Page 65: Troubleshooting
Troubleshooting: Heating Sequence of Operation IGNITION AND CALL FOR LOW FIRE WITH TWO−STAGE THERMOSTAT Safety Check Verify There Is No Main Burner Flame After Indoor blower OFF Heat OFF Delay (Low Heat Speed) Limit Combustion Air Limit De−Energize Error Code Indoor Blower Inducer On Switch...
Page 66 Troubleshooting: Heating Sequence of Operation (Continued) CALL FOR HIGH FIRE WITH TWO−STAGE THERMOSTAT 2 Stage Thermostat 1st Call for High Fire? 2nd Stage Recognition Delay (30 Seconds) Combustion Air Inducer ON (100% Rate Speed) High Pressure Switch Increase Combustion Error Code Wait 5 Closes Within Air Inducer Speed...
Page 67 Troubleshooting: Heating Sequence of Operation (Continued) CALL FOR HEAT SATISFIED RUN MODE (TWO−STAGE THERMOSTAT) RUN MODE (SINGLE−STAGE THERMOSTAT) FIRST OR SECOND−STAGE CALL FOR HEAT ALL INPUTS MONITORED (LIMIT, PRESSURE, ALL INPUTS MONITORED (LIMIT, PRESSURE, CALL FOR HEAT/COOL, FLAME LEVEL). CALL FOR HEAT/COOL, FLAME LEVEL). 2nd Stage Heat 2nd Stage Call for Heat...
Page 68 Troubleshooting: Heating Sequence of Operation (Continued) IGNITION AND CALL FOR HEAT WITH SINGLE−STAGE THERMOSTAT Safety Check Verify There Is No Main Burner Indoor Blower OFF After Flame Heat OFF Delay (Low Heat Speed) Indoor Blower Limit Limit De−Energize Combustion Air Error Code Switch Closes Within 3...
Page 69: Troubleshooting: Cooling Sequence Of Operation
Troubleshooting: Cooling Sequence of Operation CALL FOR COOLING 1st Stage Cooling Request Received Energize 1st Stage Cooling Contactor (Compressor & Fan) Indoor Blower On After 2−second delay Energize Indoor Blower (Per Ramping Profile) 1st Stage 2nd Stage Cooling Request Cooling Still Active? Request? Energize 2nd Stage...
Page 70 Troubleshooting: Continuous Fan Sequence of Operation CONTINUOUS LOW SPEED INDOOR BLOWER SEQUENCE OF OPERATION Call for Continuous Blower Indoor Blower On (Speed Determined by Dip Switch settings) Request Maintain Indoor for Cooling Go to Call for Cooling Blower at set speed Received? Go to Call for Heat −−...
Page 71: 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: G71MPP−36B−070−7. All service must be performed by a licensed professional installer (or equivalent), service agency, or gas supplier.
Page 72 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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