Aprilaire 8553 User Manual
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• Automatic Heating and Cooling: This mode can be useful during times of the year and in climates
when it is cool at night requiring heating but warm in the afternoon requiring cooling. Press and
release the MODE button until the word "AUTO" appears on the display. In this mode the furnace/air
conditioner will maintain temperature according to the programming previously completed unless
an override temperature has been entered. The furnace/air conditioner will operate in either the
heating or cooling mode depending on which programmed set point is closest to the room
temperature. Note that both the Snowflake “ “
and
Flame “ “ icons are on the display. The
Snowflake will flash or the Flame will flicker depending on which mode the furnace/air conditioner
is operating in.
• Turning the System Off: Press the MODE button until the word "OFF" appears on the display. In this
mode the furnace/air conditioner will not operate regardless of the temperature. The thermostat can
still be programmed, the optional outdoor temperature sensor will work and the fan will turn on if
the FAN button is pressed. To avoid frozen water pipes, DO NOT use the OFF mode for long periods
of time during sub-freezing temperatures.
NOTE: After selecting a new mode, the thermostat initiates a delay of up to 4 minutes to protect the heating and
cooling equipment.
110-790B 7/11/01 3:11 PM Page 21