Lennox International Inc G61MP Flame Signal, Temperature Rise, External Static Pressure

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TRANSDUCER (PART #78H5401)
FIGURE 38

J−Flame Signal

Amicroamp DC meter is needed to check the flame signal on the ignition control.

Flame (microamp) signal is an electrical current which passes from the furnace control through the sensor during unit opera- tion. Current passes from the sensor through the flame to ground to complete a safety circuit.

To Measure Flame Signal − Ignition Control:

A transducer (Part #78H5401 available from Lennox Repair Parts) is required to measure flame signal if meter used will not read a low micro amp sig- nal. figure38. The transducer converts mi-

croamps to volts on a 1:1 conversion. Flame signal for the SureLight control should read 0.23 or greater microamps with a lockout signal of 0.16 microamps. A digital readout meter must be used. The transducer plugs into most meters. See figure 39 for proper use of transducer.

1 − Set the volt meter to the DC voltage scale. Insert transducer into the VDC and common inputs. Ob- serve correct polarities. Failure to do so results in negative (−) values.

2 − Turn off supply voltage to control.

3 − Disconnect ignition control flame sensor wire from the flame sensor.

4 − Connect (−) lead of the transducer to flame sensor.

5 − Connect (+) lead of transducer to the ignition control sen- sor wire.

6 − Turn supply voltage on and close thermostat contacts to cycle system.

7 − When main burners are in operation for two minutes, take reading. Remember 1 DC volt = 1 DC microamp.

NOTE−MUST USE DIGITAL METER

SET DIAL TO MEASURE

VDC

(+)

RED COLLAR

INDICATES

 

 

POSITIVE

 

LEAD

(−)

(−) TO

FLAME SENSOR

(+)TO

IGNITION CONTROL SENSOR WIRE

FIGURE 39

V−TYPICAL OPERATING CHARACTERISTICS A−Blower Operation and Adjustment

1 − Blower operation is dependent on thermostat control system.

2 − Generally, blower operation is set at thermostat sub- base fan switch. With fan switch in ON position, blower operates continuously. With fan switch in AUTO position, blower cycles with demand or runs continuously while heating or cooling circuit cycles.

3 − Depending on the type of indoor thermostat, blower and entire unit will be off when the system switch is in OFF position.

B−Temperature Rise

Temperature rise for G61MP units depends on unit input, blower speed, blower horsepower and static pressure as marked on the unit rating plate. The blower speed must be

set for unit operation within the range of . RISE °F" listed on the unit rating plate.

To Measure Temperature Rise:

1 − Place plenum thermometers in the supply and return air plenums. Locate supply air thermometer in the first hori- zontal run of the plenum where it will not pick up radiant heat from the heat exchanger.

2 − Set thermostat to highest setting.

3 − After plenum thermometers have reached their high- est and steadiest readings, subtract the two readings. The difference should be in the range listed on the unit rating plate. If the temperature is too low, decrease blower speed. If temperature is too high, first check the firing rate. Provided the firing rate is acceptable, in- crease blower speed to reduce temperature. To change blower speed taps see the Blower Speed Taps section in this manual.

C−External Static Pressure

1 − Tap locations shown in figure 40.

2 − Punch a 1/4" diameter hole STATIC PRESSURE TEST

in supply and return air ple-

 

nums. Insert manometer

 

hose flush with inside edge

 

of hole or insulation. Seal

 

around the hose with perma-

 

gum. Connect the zero end

 

of the manometer to the dis-

FIGURE 40

 

charge (supply) side of the system. On ducted sys-

tems, connect the other end of manometer to the return

duct as above. For systems with non−ducted returns, leave the other end of the manometer open to the at- mosphere.

3 − With only the blower motor running and the evaporator coil dry, observe the manometer reading. Adjust blow- er motor speed to deliver the air desired according to the job requirements.

4 − External static pressure drop must not be more than 0.8" W.C.

5 − Seal around the hole when the check is complete.

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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 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 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 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 ApplicationCondensate Piping G61MP NON−DIRECT Vent Application Using Existing ChimneySide View NON−DIRECT Vent Wall Ring Termination Hose clamp Condensate AssemblyVent Nipple TEE Screw Coupling CLEAN−OUT Access −RINGS CAP HI/LO Screws−Preliminary and Seasonal Checks For Your Safety Read Before Operating−Heating Start-Up −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−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 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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