Lennox International Inc EL280DF installation instructions Heating Sequence of Operation

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Heating Sequence of Operation

When there is a call for heat, the integrated control runs a self check. The control checks for S10 primary limit, S21 secondary limit (s) and S47 rollout switch normally closed contacts. The control also checks for S102 high heat and S128 low heat prove switch normally open contacts. Once self check is complete and all safety switches are opera- tional, heat call can continue.

Two−Stage Thermostat, Two Stage Heat. Dip Switch set at

1− SureLight control energizes combustion air inducer B6 on low heat speed. Combustion air inducer runs until S128 low heat prove switch contacts close (switch must close within 2 1/2 minutes or control goes into Watchguard Pressure Switch mode. High heat prove switch S102 may also close). A 15 second pre−purge follows once S128 closes.

NOTE − If the low fire pressure switch does not close the combustion air inducer will switch to high fire. After a 15 second pre−purge the high fire pressure switch will close and the unit will begin operation on high fire. After 10 to 20 seconds of high fire operation the unit will switch to low fire. NOTE − If the furnace is operating on continuous fan mode (terminal in-

ducer will energize on high speed, the gas valve will ener- gize on second−stage heat and the furnace will operate on high fire. Furnace will stay on high fire for 60 seconds then switch to low fire.

2− SureLight control begins 20 second ignitor warm up period.

3− Gas valve opens on first stage for a 4 second trial for ignition. Ignitor stays energized during the trial or until flame sensed.

4− Flame is sensed, gas valve remains on first stage heat, ignitor de−energizes.

5− After 30 second delay, indoor blower B3 is energized on low heat speed.

The furnace will stay in this mode until first stage de- mand is satisfied OR a second stage heat demand is initiated.

6− Second stage heat demand initiated. A 30 second sec- ond stage recognition period begins.

7− The combustion air inducer ramps up to high heat speed.

8− S102 high heat prove switch closes and the gas valve energizes second stage heat.

9− B3 indoor blower switches to high heat speed.

Single−Stage Thermostat, Two Stage Heat. Dip Switch set at SINGLE"

1− SureLight control energizes combustion air inducer B6 on low heat speed. Combustion air inducer runs until S128 low heat prove switch contacts close (switch must close within 2 1/2 minutes or control goes into Watchguard Pressure Switch mode. High heat prove switch S102 may also close). A 15 second pre−purge follows once S128 closes.

NOTE − If the low fire pressure switch does not close the combustion air inducer will switch to high fire. After a 15 second pre−purge the high fire pressure switch will close and the unit will begin operation on high fire. After 10 to 20 seconds of high fire operation the unit will switch to low fire.

NOTE − If the furnace is operating on continuous fan mode (terminal in-

ducer will energize on high speed, the gas valve will ener- gize on second−stage heat and the furnace will operate on high fire. Furnace will stay on high fire for 60 seconds then switch to low fire.

2− SureLight control begins 20 second ignitor warm up period.

3− Gas valve opens on first stage for a 4 second trial for ignition. Ignitor stays energized during the trial or until flame sensed.

4− Flame is sensed, gas valve remains on first stage heat, ignitor de−energizes.

5− After 30 second delay, indoor blower B3 is energized on low heat speed.

6− A 10 minute (factory set) or 15 minute (field set) second stage heat delay period begins.

7− After the delay the combustion air inducer ramps up to high heat speed.

8− S102 high heat prove switch closes and the gas valve energizes second stage heat.

9− B3 indoor blower switches to high heat speed.

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Contents Installation Instructions EL280DF Table of ContentsUnit Dimensions − inches mm TOP ViewEL280DF Gas Furnace Safety InformationShipping and Packing List Use of Furnace as Construction Heater GeneralCombustion, Dilution & Ventilation Air Equipment in Confined Space ALL AIR from Inside Equipment in Confined Space NON−COMBUSTIBLE Floor Opening Size Downflow InstallationCombustible Floor Opening Size Setting Equipment Filters Duct System VentingTables for installations Mm of connector diameter as follows MIN MAX FAN + FAN FAN + NAT Gas Piping Carbon Monoxide Poisoning HazardGas Pipe Capacity − ft3/hr m3/hr Electrical Interior MAKE−UP BOX InstallationElectrostatic Discharge ESD Page Field Wiring Applications OFF EL280DF Schematic Wiring Diagram Integrated Control TWO−STAGE Integrated ControlFor Your Safety Read Before Lighting Unit Start−UpGas Pressure Adjustment GAS Meter Clocking ChartEL280DF DialProper Combustion High AltitudeOther Unit Adjustments Heat FAN-OFF Time in SecondsHeating Sequence of Operation Service Electrical SHOCK, Fire Or Explosion HazardEL280DF BURNER, Combustion AIR Inducer Assembly Repair Parts ListHeat Exchanger Removal Start−Up & Performance Check List Cooling Mode Temperature RiseUnit Operation Drain Line
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EL280DF specifications

Lennox International Inc. has been a leader in the HVAC (Heating, Ventilation, and Air Conditioning) industry for decades, consistently delivering high-quality and energy-efficient products. Among their lineup, the Lennox EL280DF Gas Furnace stands out as an excellent option for homeowners seeking reliable heating solutions.

The EL280DF is a two-stage gas furnace that offers improved efficiency and comfort, making it an ideal choice for moderate climates. One of the main features of the EL280DF is its energy efficiency, boasting an AFUE (Annual Fuel Utilization Efficiency) rating of up to 80%. This means that a significant portion of the fuel consumed is converted into heating energy, resulting in lower energy bills and reduced environmental impact.

Another noteworthy characteristic of the EL280DF is its quiet operation. Equipped with advanced sound-dampening technologies, the furnace operates with minimal noise, ensuring that your home remains a serene environment. This is especially important during the colder months when the furnace is often in frequent use.

The EL280DF also employs a two-stage heating system, which allows it to operate at a lower capacity during milder temperatures and ramp up to full capacity during the coldest days. This feature not only enhances comfort by maintaining a more consistent temperature but also contributes to energy savings by reducing unnecessary energy consumption.

In terms of installation, the EL280DF is designed for flexibility. It can be configured for various types of homes and installations, making it suitable for both new constructions and system replacements. Its compact size allows it to fit in tight spaces, providing versatility in home design.

Moreover, the EL280DF is equipped with a durable heat exchanger that ensures longevity and reliability. Lennox has also included features like a self-diagnostic control board, making troubleshooting easier and enhancing the overall reliability of the system.

In conclusion, the Lennox EL280DF Gas Furnace is a remarkable combination of efficiency, quiet operation, and versatility. With its two-stage heating capabilities and advanced technologies, it stands as a solid choice for homeowners looking to invest in a durable and energy-efficient heating solution. Whether building a new home or upgrading an old system, the EL280DF promises comfort and reliability during the coldest months of the year.
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