TH8320U AND TH8321U TOUCH SCREEN PROGRAMMABLE THERMOSTATS
69-1706
6
Fig. 14. Typical hookup of multistage heat pump with no auxiliary/backup heat (2H/2C heat pump).
Fig. 15. Typical hookup of single-stage heat pump with auxiliary/backup heat (2H/1C heat pump).
RC
R
O/B
Y
G
C
Y2
L
E
AUX
SI
S2
HEAT PUMP
COMPRESSOR 1
COMPRESSOR 2
M19904
CHANGEOVER
VALVE
FAN RELAY
R
C
1
1
2
2
3
4
5
5
4
4
3
3
OPTIONAL 24 VAC
COMMON CONNECTION
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED.
FACTORY INSTALLED JUMPER.
MUST CONNECT THE 24 VAC COMMON WHEN USING L. THE TERMINAL IS SHOWN AS EQUIPMENT MONITOR, CAN ALSO BE USED AS A 24 VAC
OUTPUT. SEE "L TERMINAL" SECTION FOR MORE INFORMATION.
"O/B" TERMINAL SET TO CONTROL AS EITHER "O" OR "B" IN THE INSTALLER SETUP.
OPTIONAL OUTDOOR OR INDOOR REMOTE SENSOR. AVAILABLE ON SELECT MODELS. WIRES MUST HAVE A CABLE SEPARATE FROM THE
THERMOSTAT CABLE.
OUTDOOR/INDOOR
TEMPERATURE
SENSOR
R
O/B
Y
G
C
Y2
L
E
AUX
SI
S2
HEAT PUMP
COMPRESSOR
RELAY
M19905
CHANGEOVER
VALVE
FAN RELAY
HEAT 2 RELAY
(AUXILIARY HEAT)
R
C
1
1
2
2
3
4
5
6
6
6
4
5
5
OPTIONAL 24 VAC
COMMON CONNECTION
EQUIPMENT
MONITOR
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED.
FACTORY INSTALLED JUMPER.
OUTDOOR SENSOR REQUIRED IN SYSTEM WITH FOSSIL FUEL BACKUP HEAT THAT IS NOT USING AN EXTERNAL FOSSIL FUEL KIT.
OPTIONAL OUTDOOR OR INDOOR REMOTE SENSOR. AVAILABLE ON SELECT MODELS. WIRES MUST HAVE A CABLE SEPARATE
FROM THE THERMOSTAT CABLE.
MUST CONNECT THE 24 VAC COMMON WHEN USING L. THE TERMINAL IS SHOWN AS EQUIPMENT MONITOR, CAN ALSO BE USED AS
A 24 VAC OUTPUT. SEE "L TERMINAL" SECTION FOR MORE INFORMATION.
"O/B" TERMINAL SET TO CONTROL AS EITHER "O" OR "B" IN THE INSTALLER SETUP.
EMERGENCY
HEAT RELAY
3
OUTDOOR/INDOOR
TEMPERATURE
SENSOR
