4
1.4 Wire the thermostat.
Once wiring is complete turn on 24vac.
S1
S1
W
Y
G
W2
Y2
A
S1
S1
O/B
Y
G
AUX
-E
Y2
L/A
K
RC
R
U1
U1
U2
U2
C
CONVENTIONAL
HEAT PUMP
Terminal Designations
Conventional System
Heat Pump
Terminal
Description
Terminal
Description
C
Common wire from secondary side of
cooling transformer (if 2 transformers).
C
Common wire from secondary side of
cooling transformer.
Rc*
Cooling power.
Rc
Cooling power.
R*
Heating power.
R
Heating power.
W
Heat Stage 1
O/B
Changeover valve for heat pumps.
W2
Heat Stage 2
AUX-E
Backup Heat/Emergency Heat
Y
Compressor Stage 1
Y
Compressor Stage 1
Y2
Compressor Stage 2
Y2
Compressor Stage 2
G
Fan Relay
G
Fan Relay
A
Connect to Economizer Module or
Lighting Panel (TOD).
L/A
Connect to Compressor Monitor, Zone
Panel, Economizer Module or Lighting
Panel (TOD).
U1 / U1
Universal relay for humidification,
dehumidification, ventilation, or a stage of
heating/cooling.
U1 / U1
Universal relay for humidification,
dehumidification, ventilation, or a stage of
heating/cooling.
S1 / S1
Universal input for a wired indoor, outdoor
or discharge sensor.
S1 / S1
Universal input for a wired indoor, outdoor
or discharge sensor.
K**
Connect to K on Wire Saver module.
K**
Connect to K on Wire Saver module.
*
Remove factory installed jumper for two transformer systems.
**
The THP9045A1023 Wire Saver module is used on heat/cool systems when you only have four wires at the thermostat and you
would like the thermostat to be powered with a common wire. Use the
K terminal
in place of the Y and G terminals on conventional
or heat pump systems to provide control of the fan and the compressor through a single wire—the unused wire then becomes your
common wire. See THP9045 instructions for more information.