Aprilaire 8554 - Manual (Page 22)

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can still be programmed, the optional outdoor temperature sensor will work and the heat pump 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 heat pump.
Setting High And Low Balance Points
If your system is installed with the required Model 8041 Remote Outdoor Sensor, the high and low
balance points should have been properly set by your contractor.
Heat Pumps operate by extracting energy out of the outdoor air and transferring it to the indoor air.
This process is efficient over a wide range of temperatures. However, at low outdoor temperatures
there is a point at which it becomes more economical to operate the back-up heat without the heat
pump. Conversely, the use of back-up heat with the heat pump during mild weather could use more
energy than is required to heat the home.
To review the set points, press and hold the OUTDOOR button, then press the FAN button. “Hi bP” and
its temperature value will appear on the display. Next, press the OUTDOOR button again and “Lo bP”
and its temperature value will appear on the display. After approximately 15 seconds the display will
return to normal.
110-792B 7/12/01 8:28 AM Page 22