Lennox International Inc G61MP specifications Clamshell Heat Exchanger, Flame Rollout Switches S47

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6. Clamshell Heat Exchanger

G61MP units use an aluminized steel primary and stain- less steel secondary heat exchanger assembly. Heat is transferred to the air stream from all surfaces of the heat exchanger. The shape of the heat exchanger ensures maximum efficiency.

The combustion air inducer pulls fresh air through the air intake box. This air is mixed with gas in the burner venturi and at the corbel orifices. The gas / air mixture is then burned at the entrance of each clamshell. Combustion gases are then pulled through the primary and secondary heat exchangers and exhausted out the exhaust vent pipe.

7. Flame Rollout Switches (S47)

Flame rollout switch S47 is a high temperature limit located on each side of the burner box. Each furnace is equipped with two identical switches. The limit is a N.C. SPST manu- al-reset limit connected in series with the primary limit S10. When S47 senses rollout, the circuit breaks and the ignition control immediately stops ignition and closes the gas valve.

If unit is running and flame rollout is detected, the gas valve will close and ignition control will be disabled. Rollout can be caused by a blocked heat exchanger, flue or lack of combustion air. The switch is factory set to trip (open) at 250°F and cannot be adjusted. The switch can be manually reset. To manually reset a tripped switch, push the reset but- ton located on the control.

8. Primary Limit Control (S10)

Figure 8 shows the primary limit (S10) used on G61MP units located in the heating vestibule panel. S10 is provided with a shield on some models (figure 8) and must not be removed. Note orientation of shield and limit if limit is replaced. When ex- cess heat is sensed in the heat exchanger, the limit will open. Once the limit opens, the furnace control energizes the supply air blower and de−energizes the gas valve. The limit automatically resets when unit temperature returns to nor- mal. The switch is factory set and cannot be adjusted.

9.Backup Secondary Limit Control (S113) (G61MP−090, 110, 135 only)

Backup secondary limit control S113 is a N.C. auto−reset switch located on the combustion air inducer. S113 acts as a backup to primary limit S10 in the event of an indoor blow- er failure. S113 contacts open when temperature on the CAI reaches 142°.

10. Gas Valve (GV1)

The G61MP uses a two−stage gas valve manufactured by Honeywell (figure 35) or White Rodgers (figure 36). The valves are internally redundant to assure safety shut−off. If the gas valve must be replaced, the same type valve must be used.

24VAC terminals and gas control knob or switch are located on the valve. All terminals on the gas valve are connected to wires from the electronic ignition control. 24V applied to the ter- minals energizes the valve.

Inlet and outlet pressure taps are located on the valve. A regu- lator adjustment screw is located on the valve.

LPG change over kit s are available from Lennox. Kits include burner orifices and a gas valve regulator conversion kit.

The burner box is sealed and operates under a negative pressure. A pressure hose is connected from the burner box to the gas valve. The gas valve senses the pressure in the burner box and changes gas valve outlet (manifold) pressure based on changes in the burner box pressure. The intent is to compensate for different vent configura- tions which can greatly affect the rate of the unit.

PRIMARY LIMIT LOCATION

limit shield

090, −110 and

−135 only

limit faces shield

FIGURE 8

11.Combustion Air Inducer Prove Switch (S18)

All G61MP units are equipped with combustion air prove switches located on the combustion air inducer housing. G61MP−045 and −070 (figure 10) units have two combustion air proving switches. G61MP−090, −110 and −135 units are equipped with two dual prove switch semblies" consist- ing of two switches acting as one. See figure 9. The switches are connected to the cold end header box by means of a flexible hose that monitors negative air pressure in the cold end header box.

The switches are a single-pole single-throw proving switch electrically connected to the furnace control. The purpose of the switch is to prevent burner operation if the combustion air inducer is not operating or if the flue becomes obstructed.

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Contents G61MP Table of ContentsOptional Accessories − Must be Ordered Extra SpecificationsAfue Direct Vent G61MP−36B−045 Performance Less Filter Blower Data1495 2340 1285 1385 2410 G61MP Parts Arrangement Glass AssemblyTOP CAP Sight BlowerCircuit Breaker CB8 Door Interlock Switch S51−Control Box Control Transformer T1 Integrated Control Board A92Page Integrated Control Board Terminals 120VAC Neutral TWO−STAGE Integrated Control Board120VAC Line Integrated Control Board 5 Pin TerminalSecondary Limit Controls S21 −Blower Compartment Blower Motor B3 and Capacitor C4DS1 DS2 Description Supply AIR BlowerIgnitor −Heating Components Flame SensorBurners Figure Ignitor Bracket Burners Front View Burners TOP ViewCombustion Air Inducer Prove Switch S18 Flame Rollout Switches S47Clamshell 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 Outdoor Termination Kits and Corresponding Equivalencies II−PLACEMENT and Installation−Vent Piping Guidelines Minimum Vent Pipe Lengths −PVC Joint Cementing ProcedureMaximum Vent Pipe Lengths Upflow or Downflow Direct or NON-DIRECT Vent Applications − Venting PracticesTypical Exhaust Pipe Connections From indoors and flue gases are discharged outdoors Direct Vent applications where combustion air is takenReducer Plug ReducerSweep ELL Carbon Monoxide Poisoning HazardPage − G61MP Vent Termination − AIR Inlet of Other Appliance Exhaust Pipe Termination Size Reduction Side View Front ViewG61MP Direct Vent Application Using Existing Chimney ANGLE−CUT in DirectionCondensate Piping G61MP NON−DIRECT Vent Application Using Existing ChimneySide View NON−DIRECT Vent Wall Ring Termination Vent Nipple TEE Screw Coupling CLEAN−OUT Access Condensate AssemblyHose clamp −RINGS CAP HI/LO Screws−Preliminary and Seasonal Checks For Your Safety Read Before Operating−Heating Start-Up IV−HEATING System Service Checks A−C.S.A. Certification −Safety or Emergency Shutdown−Testing Gas Piping −Extended Period Shutdown−Check Manifold Pressure −Testing Gas Supply Pressure− Proper Gas Flow Approximate − Proper Combustion− Condensate pH Range − High Altitude−Temperature Rise −Flame Signal−External Static Pressure −Blower Speed Taps VI−MAINTENANCEPage Page VII− Wiring and Sequence of Operation Sequence of Operation On Next Heating Sequence of Operation Normal Operation DS1 and DS2 Simultaneous Slow Flash YES See BOX a LOW Flame Signal 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 Transformer CoolLED#2−Off Miswiring of furnace or improper con − Both diagnostic lights fail to light upDoor interlock switch failure − Diagnostic lights flash the roll−out− Diagnostic lights flash the limit failure mode Uous fan demand Primary, secondary or backup seconLED#1−Slow Flash Miswiring of furnace or improper Connections at limit switchesLED#1−Off Prove switch lines damaged Switch failure code 2.5 minutes afterCondensate in prove switch line Prove switch does not close due to aSwitch code Terminating the unit − Diagnostic lights flash the pressureWith a heating demand Installed − After 5 tries the control diagnostics− Diagnostic lights flash roll−out fail − Roll−out switch trips duringFails to stay lit Operation. Problem is characterized − Combustion air inducer energizesNostic lights flash low flame sense Burner Mode Er motorLED#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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