Honeywell T10 Pro Install Manual page 2

Wiring UWP
Push down on the tabs to put the wires into the inner holes of their corresponding
termi nals on the UWP (one wire per terminal) until they are firmly in place. Gently
tug on the wires to verify they are secure. If you need to release the wires again,
push down the terminal tabs on the sides of the UWP.
Terminal designations
Conventional Systems
Terminal
Input for a wired indoor,
S/S
outdoor sensor
Y Compressor Stage 1
Y2 Compressor Stage 2
G Fan Relay
24VAC Common wire from
C secondary side of cooling
transformer (if 2 transformers)
Connect to K on C-wire
K*
adaptor
Relay for humidifier,
U/U**
dehumidifier, or ventilator
A
W Heat Stage 1
W2 Heat Stage 2
R 24 VAC Heating transformer
Rc 24 VAC Cooling transformer
* The THP9045A1098 C-wire adaptor is used on heat/cool systems when you only have four wires at
the thermostat and you need a fifth wire for 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.
** See note on Wiring U terminals on the following page.
This wiring is just an example,
yours may vary.
Description
Heat pump systems
Terminal
Input for a wired indoor,
S/S
outdoor sensor
Y Compressor Stage 1
Y2 Compressor Stage 2
G Fan Relay
24VAC Common wire from
C secondary side of cooling
transformer
Connect to K on C-wire
K*
adaptor
Relay for humidifier,
U/U**
dehumidifier, or ventilator
Connect to compressor
L/A
monitor
Changeover valve for heat
O/B
pumps
Aux Backup Heat
E Emergency Heat
R 24 VAC Heating transformer
Rc 24 VAC Cooling transformer
3
Description