Other Unit Adjustments

Primary and Secondary Limits

The primary limit is located on the heating compartment vestibule panel. The secondary limits (if equipped) are lo- cated in the blower compartment, attached to the back side of the blower. These auto reset limits are factory−set and re- quire no adjustment.

Flame Rollout Switches

These manually reset switches are located on the burner box.

Pressure Switch

The pressure switch is located in the heating compartment adjacent to the combustion air inducer. The switch checks for proper combustion air inducer operation before allow- ing ignition trial. The switch is factory−set and requires no adjustment.

Temperature Rise

After the furnace has been started, and supply and return air temperatures have been allowed to stabilize, check the temperature rise. If necessary, adjust the blower speed to maintain the temperature rise within the range shown on the unit nameplate. Increase the blower speed to decrease the temperature. Decrease the blower speed to increase the temperature rise. Failure to adjust the temperature rise may cause erratic limit operation.

Fan Control

The fan−on time of 30 seconds is not adjustable. The heat fan−off delay (amount of time that the blower operates after the heat demand has been satisfied) may be adjusted by changing DIP switches 3 and 4. See figure 23 and table 10. The unit is shipped with a factory fan−off delay setting of 90 seconds. The fan−off delay affects comfort and is adjust- able to satisfy individual applications. Adjust the fan−off delay to achieve a supply air temperature between 90° and 110°F at the moment that the blower is de−energized. Lon- ger off delay settings provide lower return air temperatures; shorter settings provide higher return air temperatures. See figure 23.

HEAT FAN-OFF TIME IN SECONDS

60sec.90sec.





1	2	3	4	5	1		2	3	4	5
	120sec.						180sec.





1	2	3	4	5		1	2	3	4	5

To adjust fan−off timing, flip dip switch to desired setting.

FIGURE 23

Input Voltage Requirements

The circuit is designed to be operated with AC voltage. A voltage of 12 to 33VAC is required to energize the motor. Expected current draw will be less than 20mA.

Blower Speeds

Follow the steps below to change the blower speeds. 1 − Turn off electrical power to furnace.

2 − Remove blower access panel.

3 − Disconnect existing speed tap at integrated control speed terminal.

NOTE − Termination of any unused motor leads must be insulated.

4 − Place unused blower speed tap on integrated control PARK" terminal or insulate.

5 − Refer to blower speed selection chart on unit wiring dia- gram for desired heating or cooling speed. See Blower performance data beginning on the next page.

6 − Connect selected speed tap at integrated control speed terminal.

7 − Resecure blower access panel.

8 − Turn on electrical power to furnace.

9 − Recheck temperature rise. Electronic Ignition

The integrated control has an added feature of an internal Watchguard control. The feature serves as an automatic re- set device for integrated control lockout caused by ignition failure. This type of lockout is usually due to low gas line pressure. After one hour of continuous thermostat demand for heat, the Watchguard will break and remake thermostat demand to the furnace and automatically reset the inte- grated control to begin the ignition sequence.

Page 27

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.