Aprilaire 8535 - Manual (Page 13)

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Setting High And Low Balance Points
(Models 8536 & 8537 only)
High and low balance points can only be accessed if the Aprilaire Model 8041 Remote Outdoor Sensor
has been installed. To check if this optional accessory has been installed, press the Outdoor button. If a
temperature appears, the Model 8041 Remote Outdoor Sensor has been installed.
During heating, 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. This is called the Low Balance Point, “Lo bP”.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. At
outdoor temperatures exceeding the High Balance Point, “Hi bP”, use of the back-up heat is limited
to Emergency Heat operation only.
To review the set points, press and hold the Outdoor button and 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.
110-965B 7/12/01 9:12 AM Page 13