035-18549-000-B-0402
Unitary Products Group
19
OPERATION BELOW 0°F OUTDOOR TEMPERATURE
1.
At 0°F outdoor temperature, the low temperature
compressor cutoff thermostat 1TH contacts 1 and 3
will open, de-energizing contactor 1M which shuts
down the compressor. Contacts 1 and 2 of thermo-
stat 1TH are closed when contacts 1 and 3 are
open. This feature allows the standby electric heat
(if installed) to operate under control of first stage
heating TH1 of the room thermostat whenever the
compressor is shut-down by the 1TH control. The
supplemental electric heat will continue to be con-
trolled by the second stage TH2 of the room ther-
mostat same as described under Item 8 of
HEATING OPERATION.
2.
The indoor section blower operation will be con-
trolled by the first stage heating TH1 of the room
thermostat if the fan switch is in the “AUTO” posi-
tion.
EMERGENCY HEAT OPERATION
When the system switch on the room thermostat is
placed in the EMERGENCY HEAT position, operation
is as follows:
1.
The emergency heat light on the room thermostat
will be energized.
2.
Compressor will not operate because the Y circuit
of the room thermostat cannot be energized.
3.
Supplemental
and
standby
electric
heat
(if
installed) will be controlled by first stage heating
TH1 of room thermostat.
4.
Indoor section blower will also be controlled by first
stage heating TH1 if fan switch is in the “AUTO”
position.
