Lennox International Inc G61MP Combustion air inducer energizes, Roll−out switch trips during

Page 52

PROBLEM 5: BURNERS LIGHT WITH HEATING DEMAND BUT UNIT SHUTS DOWN

PREMATURELY (CONT.)

Condition

Possible Cause

Corrective Action/Comments

 

 

 

5.3

 

ACTION 1 − Check that the manifold pressure

− Combustion air inducer energizes

 

matches value listed on nameplate. See installa-

 

tion instructions for proper procedure.

with a heating demand.

5.3.1

ACTION 2 − Verify that the installed orifice size

− Burners light.

Unit is firing above 100% of the

match the size listed on the nameplate or installa-

− Roll−out switch trips during the

tion instructions.

nameplate input.

ACTION 3 − Check gas valve sensing hose to in-

heating demand.

 

sure no leaks are present.

− Diagnostic lights flash roll−out fail-

 

ACTION 4 − Check the input rate to verify rate

ure.

 

matches value listed on nameplate.

 

5.3.2

ACTION 1 − Tighten orifice until leak is sealed.

 

NOTE: Be careful not to strip orifice threads.

 

 

LED#1−On

Gas orifices leak at the manifold

ACTION 2 − Check for gas leakage at the

threaded orifice connection. Use approved meth-

LED#2−Slow Flash

connection.

od for leak detection (see unit instructions).

 

 

 

 

 

 

5.3.3

ACTION 1 − Check for air leakage at all joints in

 

Air leakage at the connections

the heat exchanger assembly. Condition will

 

cause high CO2 with high CO.

 

between the primary heat exchanger,

 

ACTION 2 − Seal leakage if possible, replace

 

secondary heat exchanger, and

heat exchanger if necessary, tag and return heat

 

combustion air blower.

exchanger to proper Lennox personnel.

 

 

 

 

5.3.4

ACTION 1 − Check for sooting deposits or other

 

Insufficient flow through the heat

restrictions in the heat exchanger assembly.

 

Clean assembly as outlined in instruction manu-

 

exchanger caused by a sooted or

 

al.

 

restricted heat exchanger.

ACTION 2 − Check for proper combustion.

 

 

 

 

5.3.5

ACTION 1 − Check that the burners are firing into

 

 

 

Burners are not properly located in

the center of the heat exchanger openings. Cor-

 

the burner box.

rect the location of the burners if necessary.

 

 

 

 

 

5.4

5.4.1

 

− Combustion air inducer energizes

ACTION 1 − Check for proper flow of exhaust

Recirculation of flue gases. This

gases away from intake vent. Remove any ob-

with a heating demand.

stacles in front of the intake and exhaust vent

− Burners light roughly and the unit

condition causes rough ignitions and

which would cause recirculation.

fails to stay lit.

operation. Problem is characterized

ACTION 2 − Check for correct intake and exhaust

− Diagnostic lights flash watchguard

by nuisance flame failures.

vent installation. See instructions

 

flame failure.

 

 

 

5.4.2

ACTION 1 − Remove burner and inspect the

LED#1−Alternating Slow Flash

cross−overs for burrs, or any restriction or if

Improper burner cross−overs

crossover is warped. Remove restriction or re-

LED#2−Alternating Slow Flash

place burners.

 

 

 

 

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Contents Table of Contents G61MPOptional Accessories − Must be Ordered Extra SpecificationsAfue Direct Vent Blower Data G61MP−36B−045 Performance Less Filter1495 2340 1285 1385 2410 Glass Assembly G61MP Parts ArrangementTOP CAP Sight BlowerDoor Interlock Switch S51 Circuit Breaker CB8−Control Box Control Transformer T1 Integrated Control Board A92Page TWO−STAGE Integrated Control Board Integrated Control Board Terminals 120VAC Neutral120VAC Line Integrated Control Board 5 Pin Terminal−Blower Compartment Blower Motor B3 and Capacitor C4 Secondary Limit Controls S21DS1 DS2 Description Supply AIR Blower−Heating Components Flame Sensor IgnitorBurners Figure Ignitor Bracket Burners Front View Burners TOP ViewFlame Rollout Switches S47 Combustion Air Inducer Prove Switch S18Clamshell Heat Exchanger Primary Limit Control S10CAI & Cold END Header BOX Assembly Dual Combustion AIR Prove SwitchFirst stage Negative Pressure Second stage Positive Combustion Air Inducer B6 II−PLACEMENT and Installation Outdoor Termination Kits and Corresponding Equivalencies−Vent Piping Guidelines Minimum Vent Pipe Lengths −PVC Joint Cementing ProcedureMaximum Vent Pipe Lengths − Venting Practices Upflow or Downflow Direct or NON-DIRECT Vent ApplicationsTypical Exhaust Pipe Connections Direct Vent applications where combustion air is taken From indoors and flue gases are discharged outdoorsReducer Plug 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 ApplicationCondensate Piping G61MP NON−DIRECT Vent Application Using Existing ChimneySide View NON−DIRECT Vent Wall Ring Termination Condensate Assembly Vent Nipple TEE Screw Coupling CLEAN−OUT AccessHose clamp −RINGS CAP HI/LO Screws−Preliminary and Seasonal Checks For Your Safety Read Before Operating−Heating Start-Up −Safety or Emergency Shutdown IV−HEATING System Service Checks A−C.S.A. Certification−Testing Gas Piping −Extended Period Shutdown−Testing Gas Supply Pressure −Check Manifold Pressure− Proper Gas Flow Approximate − Proper Combustion− High Altitude − Condensate pH Range−Temperature Rise −Flame Signal−External Static Pressure 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 Single VIII− Field Wiring Applications and Jumper SettingsTWO Cool Transformer− Both diagnostic lights fail to light up LED#2−Off Miswiring of furnace or improper conDoor interlock switch failure − Diagnostic lights flash the roll−outUous fan demand Primary, secondary or backup secon − Diagnostic lights flash the limit failure modeLED#1−Slow Flash Miswiring of furnace or improper Connections at limit switchesSwitch failure code 2.5 minutes after LED#1−Off Prove switch lines damagedCondensate in prove switch line Prove switch does not close due to aTerminating the unit − Diagnostic lights flash the pressure Switch codeWith a heating demand Installed − After 5 tries the control diagnostics− Roll−out switch trips during − Diagnostic lights flash roll−out failFails to stay lit Operation. Problem is characterized − Combustion air inducer energizesMode Er motor Nostic lights flash low flame sense BurnerLED#1−Slow Flash 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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