Aprilaire 8553 User Manual
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Optional Settings For Additional Thermostat Features
The Model 8553 thermostat is equipped with 5 DIP switches located inside the thermostat on the printed
circuit board. These switches are preset by the factory to typical home heating and cooling system
requirements. The installing contractor also reviewed the settings during installation to be sure the
thermostat will operate properly with your heating and cooling system.
The DIP switches can however be changed to customize the thermostat’s operation to your particular
needs. This should only be done after consulting with your contractor.
The Model 8553 DIP switches control the following functions:
No. 1 – 4 or 2 Events Per Day. The switch is factory preset for 4 events per day; Morning, Day, Evening,
and Night. If it is more convenient you can select a 2-event day, Morning and Night, by moving this
switch to the ON position.
No. 2 – Smart Fan. The thermostat is factory preset with the Smart Fan option off. This allows the system
fan to operate normally with the heating and cooling equipment. If the Smart Fan option is turned on
by placing the DIP switch in the ON position when the Fan button on the thermostat is pushed
(indicated by the fan icon on the display), the system fan will run continuously during the Morning,
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