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.

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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Elite Series Gas Furnace Upflow/Horizontal Air Discharge, EL280UH specifications

Lennox International Inc. has established itself as a leader in the heating and cooling industry, providing innovative solutions for both residential and commercial environments. One of their notable products is the EL280UH, a high-efficiency gas furnace designed to offer optimal comfort while minimizing energy consumption.

The EL280UH operates with an impressive Annual Fuel Utilization Efficiency (AFUE) rating of up to 80%. This efficiency rating means that 80% of the fuel consumed is converted into heat, making it a cost-effective option for homeowners looking to reduce their utility bills. The furnace’s design is tailored to deliver reliable warmth during the coldest months, ensuring a comfortable home environment.

A key feature of the EL280UH is its two-stage heating capability. This technology allows the furnace to operate at a lower heating output for less demanding conditions, which not only conserves energy but also helps maintain a more consistent temperature in the home. When the demand for heat increases, the furnace can seamlessly transition to its higher output setting, providing quick and effective heating when needed.

Additionally, the EL280UH is equipped with a durable cabinet that minimizes heat loss, enhancing overall performance. The design incorporates several sound-dampening features as well, which contributes to quieter operation, allowing homeowners to enjoy a serene indoor environment.

The furnace also includes an advanced control system that integrates easily with smart home technology. This feature enables users to monitor and adjust their heating settings from anywhere using a smartphone app, creating added convenience and control over home heating.

Safety is another paramount aspect of the EL280UH. It includes an integrated flame sensor and pressure switch, ensuring reliable operation while minimizing risks associated with furnace malfunctions. The design adheres to stringent safety standards, providing users with peace of mind.

In summary, the Lennox EL280UH furnace stands out for its high efficiency, advanced features, and commitment to user safety. Its two-stage heating capability, quiet operation, and smart home integration make it an excellent choice for homeowners looking to enhance their heating system while being energy-conscious. The EL280UH embodies Lennox's dedication to quality and innovation, ensuring that comfort and efficiency go hand in hand.