Comfort Stat CDT901 - Manual (Page 94)

CDT900 Series Touchscreen Programmable Thermostata
Operation in Heat Mode
When the outdoor temperature is below the
Compressor Lockout Temperature, only the
Auxiliary Heat operates.
When the outdoor temperature is above the
Auxiliary Lockout Temperature, only the
Compressor operates. See Fig. 34.
AUXILIARY LOCKOUT
TEMPERATURE
COMPRESSOR
LOCKOUT
TEMPERATURE
OU
TDOO
R
TE
MPE
R
A
T
URE
BOTH
OMPRESSOR AND
AUXILIARY HEAT
AUXILIARY ONLY
COMPRESSOR
Fig. 34. Heat Pump Operation with Lockout
Temperatures Set.
When the outdoor temperature is between the
two temperatures, both the Compressor and
Auxiliary Heat operate.
Operation in Emergency Heat Mode
Once the thermostat is placed into the
Emergency Heat mode, the compressor and
auxiliary lockout features are turned off. In
the Emergency heat mode, the compressor
is locked out. The first stage of heat is
whatever is connected to the E terminal.
The second stage of heat is connected to
the Aux. terminal. Usually the emergency
and auxiliary heat sources are electric strip
heat in these cases.
Operating Sequence
The thermostat energizes specific
terminal(s), depending on the demand for
heating, cooling or fan. The thermostat
screen shows the time, inside temperature,
system and fan selections. Additional
indicators are shown when the heating,
cooling or fan is energized. See Tables 9 - 11
for specification information.
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