TESTING
conventional heat pump system with the exception that the heat pump is never allowed to
run when the fossil fuel furnace is energized. Whenever the thermostat calls for second
stage (auxiliary) heat, the compressor ‘Y’ relay is de-energized along with the fan ‘G’ relay
and the ‘A’ relay energizes the fossil fuel furnace. With the installation of an outdoor sensor,
both high and/or low balance point control can be used to prioritize heat pump or fossil fuel
operation based on a selected outdoor temperature.
TESTING LOW BALANCE POINT (Heat Pump or Fossil Fuel)
When an outdoor sensor is used with the 44-800, Installer Option 18:LB allows you to
select a low balance point temperature. When the outdoor temperature falls below the low
balance point setting, a call for heat from the thermostat automatically energizes the
auxiliary heat ‘A’ relay. To test the low balance point setting, set 18:LB above the displayed
outdoor temperature and force a call for heating. The ‘A’ relay will energize the compressor
‘Y’ relay will be bypassed. Set 18:LB below the displayed outdoor temperature and force a
call for heating. The compressor ‘Y’ relay will energize and the ‘A’ relay will not energize as
long as the thermostat does not call for second stage. After testing, reset the low balance
point temperature to a normal operating range.
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