Lennox International Inc Understanding Integrated Control Features in EL280UH Furnace Models

Integrated Control

EL280UH units are equipped with a two−stage integrated control. This control manages ignition timing and fan off delays based on selections made using the control DIP switches. The control includes an internal watchguard fea- ture which automatically resets the integrated control when it has been locked out. After one hour of continuous ther- mostat demand for heat, the watchguard will break and re- make thermostat demand to the furnace and automatically reset the control to relight the furnace.

DIP Switch Settings

Switch 1 −− Thermostat Selection −− This unit may be used with either a single−stage or two−stage thermostat. The thermostat selection is made using a DIP switch which must be properly positioned for the particular application. The DIP switch is factory−positioned for use with a two− stage thermostat. If a single−stage thermostat is to be used, the DIP switch must be repositioned.

a − Select " for two−stage heating operation con- trolled by a two−stage heating thermostat (factory set- ting);

b − Select " for two−stage heating operation con- trolled by a single−stage heating thermostat. This set- ting provides a timed delay before second−stage heat is initiated.

Switch 2 −− Second Stage Delay (Used with Single− Stage Thermostat Only) −− This switch is used to deter- mine the second stage on delay when a single−stage ther- mostat is being used. The switch is factory−set in the OFF position, which provides a 10−minute delay before second− stage heat is initiated. If the switch is toggled to the ON position, it will provide a 15−minute delay before second− stage heat is initiated. This switch is only activated when the thermostat selector jumper is positioned for SINGLE− stage thermostat use.

Switches 3 and 4 −− Heating Blower−Off Delay −− The heating blower−on delay of 30 seconds is not adjustable. The heating blower−off delay (time that the blower operates after the heating demand has been satisfied) can be ad-

justed by moving switches 3 and 4 on the integrated con- trol. The unit is shipped from the factory with a heating blower−off delay of 90 seconds. The heating blower off delay affects comfort and is adjustable to satisfy individual applications. Adjust the blower off delay to achieve a sup- ply air temperature between 90° and 110°F at the exact moment that the blower is de−energized. Longer off delay settings provide lower supply air temperatures; shorter set- tings provide higher supply air temperatures.Table 11 pro- vides the blower off timings that will result from different switch settings.

TABLE 11

Heating Blower−Off Delay Switch Settings

Blower Off Delay	Switch 3	Switch 4
(Seconds)
60	Off	On
90	Off	Off
(factorysetting)
120	On	Off
180	On	On

Switch 5 −− Cooling Blower−Off Delay −− The cooling blower−off delay (time that the blower operates after the cooling demand has been satisfied) can be adjusted by moving switch 5 on the integrated control. The switch is fac- tory−set in the OFF position, which provides a cooling blow- er−off delay of 45 seconds. If the switch is toggled to the ON position, it will provide a 2−second cooling blower−off delay

On−Board Link W951 Heat Pump (R to O)

On−board link W951 is a clippable connection between ter- minals R and O on the integrated control. W951 must be cut when the furnace is installed in applications which include a heat pump unit and a thermostat which features dual fuel use. If the link is left intact, terminal

gized eliminating the HEAT MODE in the heat pump. On−Board Link W915 2 Stage Compr (Y1 to Y2) On−board link W915 is a clippable connection between ter- minals Y1 and Y2 on the integrated control. W915 must be cut if two−stage cooling will be used. If the link is not cut the outdoor unit will operate in second−stage cooling only and the indoor blower will operate on high cool speed only.

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