Wiring conventional systems: forced air and hydronics
1H/1C System (1 transformer)
R
Power [1]
Rc
[R+Rc joined by Slider Tab] [2]
Y
Compressor contactor
C
24VAC common [3]
W
Heat
G
Fan
Heat-only System
R
Power [1]
Rc
[R+Rc joined by Slider Tab] [2]
C
24VAC common [3]
W
Heat
Heat-only System (Series 20) [5]
R
Series 20 valve terminal "R" [1]
Rc
[R+Rc joined by Slider Tab] [2]
Y
Series 20 valve terminal "W"
C
24VAC common [3]
W
Series 20 valve terminal "B"
Heat-only System
(power open zone valve) [5]
R
Power [1]
Rc
[R+Rc joined by Slider Tab] [2]
W
Valve
C
24VAC common [3]
Wiring heat pump systems
1H/1C Heat Pump System
R
Power [1]
Rc
[R+Rc joined by Slider Tab] [2]
Y
Compressor contactor
C
24VAC common [3]
O/B Changeover valve [7]
G
Fan
W
Do not use this terminal for heat pump
applications!
NOTES
Wire specifications: Use 18- to 22-gauge thermostat wire. Shielded cable is not required.
[1]
Power supply. Provide disconnect means and overload
protection as required.
[2]
Move R-Slider Tab on UWP to the R setting. For more
information, see "Setting Slider Tabs" on page 3
[3]
Optional 24VAC common connection.
[4]
Common connection must come from cooling transformer.
1H/1C System (2 transformers)
R
Power (heating transformer) [1]
Rc
Power (cooling transformer) [1]
Y
Compressor contactor
C
24VAC common [3, 4]
W
Heat
G
Fan
Heat-only System with Fan
R
Power [1]
Rc
[R+Rc joined by Slider Tab] [2]
C
24VAC common [3]
W
Heat
G
Fan
Cool-only System
R
Power [1]
Rc
[R+Rc joined by Slider Tab] [2]
Y
Compressor contactor
C
24VAC common [3]
G
Fan
2H/1C Heat Pump System (TH4210U only)
R
Power [1]
Rc
[R+Rc joined by Slider Tab] [2]
Y
Compressor contactor
C
24VAC common [3]
O/B Changeover valve [7]
G
Fan
AUX Auxiliary heat
E
Emergency heat
W
Do not use this terminal for heat pump
applications!
[5]
In ISU set Heat system type to Radiant Heat. Set number of
cool stages to 0.
[7]
In Installer Setup, set changeover valve to O (for cool
changeover) or B (for heat changeover).
4