Heat Pumps With Supplemental Heat - Honeywell T8631A Owner's Manual

HEAT PUMP WITH SUPPLEMENTAL HEAT
HEAT PUMPS ARE DIFFERENT (T8631R)
Heat pump systems usually have a supplemental,
second stage heating system that operates only
when necessary . The Honeywell Chronotherm III
Thermostat for heat pumps is designed to minimize
the more expensive second-stage operation,
indicated by the green AUX light on the switching
subbase.
With your Chronotherm III Thermostat, you will
notice that your compressor operates continuously
during the recovery period . This may appear to
waste energy, but it is actually more efficient.
Multiple ON-OFF cycles are neither necessary to
achieve comfort, nor as efficient for heat pump
systems. By reducing the number of cycles, you
reduce the strain on your system and extend
equipment life.
HEAT PUMPS ARE TWO SYSTEMS IN ONE
MILD WEATHER
OUTDOORS
OUTDOOR
AIR
HEAT
TRANSFER
In mild weather, almost all of the demand for heat in
buildings can be met by the heat pump compressor.
This first stage process of moving heat indoors is
very economical. As the air becomes colder outside,
the first stage may be unable to deliver enough heat
to maintain the desired comfort level in the building.
INDOORS OUTDOORS
AUXILIARY
HEATING
ELEMENT
OFF
OUTDOOR
AIR
INDOOR
AIR
HEAT
TRANSFER
During high heat demand, the thermostat will call for
additional second stage power from the auxiliary
heat system . This auxiliary heat is commonly
electric resistance heat and is two to three times
more expensive to operate than the compressor.
SEVERE WEATHER
31
INDOORS
AUXILIARY
HEATING
ELEMENT
ON
INDOOR
AIR
32