Lennox International Inc G61MP Condition Possible Cause Corrective Action/Comments, Prove switch

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PROBLEM 2: UNIT FAILS TO FIRE IN THE HEATING MODE, COMBUSTION AIR INDUCER DOES

NOT ENERGIZE (CONT.).

Condition

Possible Cause

Corrective Action/Comments

 

 

 

2.3

 

 

− Unit operates with a cooling and con-

2.3.1

 

tinuous fan demand.

Miswiring of furnace or improper

ACTION 1 − Check for correct wiring and loose

− Combustion air inducer will not start

connections. Correct wiring and/or replace any

connections to combustion air induc-

loose connections.

with a Heating demand.

er.

 

− Diagnostic lights flash the pressure

 

 

 

switch failure code 2.5 minutes after

 

 

heating demand.

 

 

 

2.3.2

ACTION 1 − If there is 120V to combustion air in-

 

Combustion air inducer failure.

ducer and it does not operate, replace combus-

LED#1−Off,

tion air inducer.

 

 

LED#2−Slow Flash

 

 

 

 

 

PROBLEM 3: UNIT FAILS TO FIRE IN THE HEATING MODE, COMBUSTION AIR INDUCER

ENERGIZES, IGNITOR IS NOT ENERGIZED.

Condition

Possible Cause

Corrective Action/Comments

 

 

 

3.1

3.1.1

 

− Unit operates with a cooling and

Prove switch does not close due to

ACTION 1 − Check that the prove switch lines are

correctly routed. Correctly route pressure switch

continuous fan demand.

incorrect routing of the pressure

lines.

− Combustion air inducer energizes

switch lines.

 

with a heating demand.

 

 

3.1.2

 

− Diagnostic lights flash the pressure

ACTION 1 − Remove any obstructions from the

Prove switch does not close due to

switch failure code 2.5 minutes after

the pressure lines and/or taps.

heating demand.

obstructions in the pressure lines.

 

 

 

 

 

3.1.3

ACTION 1 − Check prove switch lines for leaks.

LED#1−Off

Prove switch lines damaged

Replace any broken lines.

 

 

 

LED#2−Slow Flash

3.1.4

ACTION 1 − Check prove switch lines for conden-

 

Condensate in prove switch line.

sate. Remove condensate from lines.

 

 

 

 

 

 

 

ACTION 1 − Check the differential pressure

 

3.1.5

across the prove switch. This pressure should

 

Prove switch does not close due to a

exceed the set point listed on the switch.

 

ACTION 2 − Check for restricted inlet vent. Re-

 

low differential pressure across the

 

move all blockage.

 

prove switch.

 

ACTION 3 − Check for proper vent sizing and

 

 

 

 

run length.

 

 

 

 

3.1.6

 

 

Wrong prove switch installed in the

ACTION 1 − Check that the proper prove switch

 

is installed in the unit. Replace prove switch if

 

unit, or prove switch is out of

 

necessary.

 

calibration.

 

 

 

 

 

3.1.7

ACTION 1 − Check for correct wiring and loose

 

 

 

Miswiring of furnace or improper

connections. Correct wiring and/or replace any

 

connections at prove switch.

loose connections.

 

 

 

 

 

 

3.1.8

ACTION 1 − If all the above modes of failure have

 

been checked, the prove switch may have failed.

 

Prove switch failure.

Replace prove switch and determine if unit will

 

operate.

 

 

 

 

 

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Contents Table of Contents G61MPAfue SpecificationsOptional Accessories − Must be Ordered Extra Direct Vent Blower Data G61MP−36B−045 Performance Less Filter1495 2340 1285 1385 2410 TOP CAP Glass AssemblyG61MP Parts Arrangement Sight Blower−Control Box Control Transformer T1 Door Interlock Switch S51Circuit Breaker CB8 Integrated Control Board A92Page 120VAC Line TWO−STAGE Integrated Control BoardIntegrated Control Board Terminals 120VAC Neutral Integrated Control Board 5 Pin TerminalDS1 DS2 Description −Blower Compartment Blower Motor B3 and Capacitor C4Secondary Limit Controls S21 Supply AIR BlowerBurners Figure −Heating Components Flame SensorIgnitor Ignitor Bracket Burners Front View Burners TOP ViewClamshell Heat Exchanger Flame Rollout Switches S47Combustion Air Inducer Prove Switch S18 Primary Limit Control S10First stage Negative Pressure Second stage Positive Dual Combustion AIR Prove SwitchCAI & Cold END Header BOX Assembly Combustion Air Inducer B6 II−PLACEMENT and Installation Outdoor Termination Kits and Corresponding Equivalencies−Vent Piping Guidelines Maximum Vent Pipe Lengths −PVC Joint Cementing ProcedureMinimum Vent Pipe Lengths − Venting Practices Upflow or Downflow Direct or NON-DIRECT Vent ApplicationsTypical Exhaust Pipe Connections Reducer Plug Direct Vent applications where combustion air is takenFrom indoors and flue gases are discharged outdoors ReducerCarbon Monoxide Poisoning Hazard Sweep ELLPage − G61MP Vent Termination − AIR Inlet of Other Appliance Exhaust Pipe Termination Size Reduction Front View Side ViewUsing Existing Chimney ANGLE−CUT in Direction G61MP Direct Vent ApplicationSide View NON−DIRECT Vent Wall Ring Termination G61MP NON−DIRECT Vent Application Using Existing ChimneyCondensate Piping Hose clamp Condensate AssemblyVent Nipple TEE Screw Coupling CLEAN−OUT Access −RINGS CAP HI/LO Screws−Heating Start-Up For Your Safety Read Before Operating−Preliminary and Seasonal Checks −Testing Gas Piping −Safety or Emergency ShutdownIV−HEATING System Service Checks A−C.S.A. Certification −Extended Period Shutdown− Proper Gas Flow Approximate −Testing Gas Supply Pressure−Check Manifold Pressure − Proper Combustion− High Altitude − Condensate pH Range−External Static Pressure −Flame Signal−Temperature Rise VI−MAINTENANCE −Blower Speed TapsPage Page VII− Wiring and Sequence of Operation Sequence of Operation On Next Heating Sequence of Operation See BOX a LOW Flame Signal YES Normal Operation DS1 and DS2 Simultaneous Slow Flash YESEN or Heat Demand is SATISFIED. a Five Cooling Sequence of Operation Continuous LOW Speed FAN Sequence of Operation TWO VIII− Field Wiring Applications and Jumper SettingsSingle Cool TransformerDoor interlock switch failure − Both diagnostic lights fail to light upLED#2−Off Miswiring of furnace or improper con − Diagnostic lights flash the roll−outLED#1−Slow Flash Miswiring of furnace or improper Uous fan demand Primary, secondary or backup secon− Diagnostic lights flash the limit failure mode Connections at limit switchesCondensate in prove switch line Switch failure code 2.5 minutes afterLED#1−Off Prove switch lines damaged Prove switch does not close due to aWith a heating demand Installed Terminating the unit − Diagnostic lights flash the pressureSwitch code − After 5 tries the control diagnosticsFails to stay lit Operation. Problem is characterized − Roll−out switch trips during− Diagnostic lights flash roll−out fail − Combustion air inducer energizesLED#1−Slow Flash Mode Er motorNostic lights flash low flame sense Burner Sensor rod is contaminatedService Notes

G61MP specifications

Lennox International Inc. has long been a leader in HVAC solutions, and the G61MP gas furnace exemplifies the company's commitment to innovation and energy efficiency. This high-efficiency gas furnace operates with an Annual Fuel Utilization Efficiency (AFUE) of up to 96%, allowing homeowners to save significantly on energy costs while maintaining a comfortable indoor environment.

One of the primary features of the G61MP is its modulating gas valve. This technology enables the furnace to operate at multiple levels of heating output, ensuring that it can adjust its performance according to the home’s heating demands. By modulating the heating output, the G61MP maximizes efficiency and minimizes energy waste, providing a consistent temperature and improved comfort.

The G61MP also incorporates advanced two-stage heating, which enhances its performance by reducing temperature fluctuations in the home. This feature is especially beneficial during transitional weather periods when heating needs may vary widely. With its ability to operate on a lower stage most of the time, the furnace can produce quieter operation and reduced energy consumption.

In terms of design, the G61MP includes a sealed combustion chamber that draws air from outside the home for combustion, enhancing safety and efficiency. This design feature eliminates the need for indoor air, improving indoor air quality. The furnace is also equipped with a high-efficiency ECM blower motor that not only boosts comfort but operates quietly and uses less electricity compared to traditional motors.

Further enhancing its efficiency, the G61MP utilizes a variable-speed blower, which allows for precise control of airflow throughout the home. This results in better humidity control and improved air distribution, providing an overall more comfortable environment.

The Lennox G61MP is compatible with the iComfort S30 smart thermostat, allowing homeowners to control their heating remotely, adjust settings based on their schedules, and access energy usage data. This connectivity transforms the G61MP into an integral part of a smart home ecosystem, facilitating energy conservation and comfort optimization.

Lastly, the G61MP is designed with durability in mind. Its robust construction and high-quality materials ensure reliable performance and lengthy service life. Homeowners can feel assured that they are investing in a heating solution that will meet their needs for many winters to come. In summary, the Lennox G61MP gas furnace stands out with its high efficiency, advanced technology, and user-friendly features, making it a top choice for homeowners seeking exceptional heating performance.
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