PCB0001C-01-BHP-PDII0614
4. Single Heat Pump w/ 1 Additional Heater
The fourth category of wiring configuration
schemes follows a single heat pump system,
with 1 additional heater in the system. By
definition, a single transformer is shared
between the RC1 and RH1 of the heat pump,
while an additional transformer (and
transformer connection) is required for the
additional heater.
Optional outputs include Cool/Heat Stage 2
and Economizer Damper Control. Refer to the
following charts while wiring up your system.
Note that E should not be connected to
compressor controls as there are not any
minimum compressor on-times built into the
controls for E. Typically, E is connected to the
electric heat strips used for Emergency Heat
and for supplemental heat when the Heat
Pump is unable to keep up with the heating
demands of the current situation.
Please also note that it is important to record
how the reversing valve was wired up on your
previous thermostat. This is controlled using
either B (typically blue), O (typically orange),
O/B, or B/O. If B was wired up, this typically
means that the reversing valve is being
energized during heating mode. If O was
wired up, the reversing valve is being
energized during cooling mode. If O/B or B/O
was wired up, it is important to check your
existing thermostat to see if there is a jumper
or a setting which specifies how the reversing
valve was being energized (during cooling or
heating). This setting must be applied to the
Comfort Window on the Equipment Control
page.
Screw
Terminal
Number
Connect To
Function
Std.
Wire Color*
1
Jumper to 4
RC2
Red
2
Heater 2 Transformer
+24VAC
RH2
Red
3
Jumper to 4
RH1
Red
4
Compressor
Transformer
+24VAC
RC1
Red
5
Compressor Control
Y
Yellow
6
Fan Control
G
Green
7
Emergency Heat
Control
E
White
8
Change-Over Control
B/O
Blue
12
Heater 2 Control
WH2
Dark Purple
15
-24VAC (Ground)
C
Brown/Black
**
16
Indoor Temp Probe
T1in
Black*
17
Indoor Temp Probe
T2in
Yellow*
19
Indoor Temp Probe
T3in
Red*
Screw
Terminal
Number
Connect To
Function Proprietary
Wire Color
10
Cool/Heat Stage 2
Control
Y2
NA
11
Outside
Temp/Humidity Probe
OT2in
Yellow
13
Outside
Temp/Humidity Probe
OH1in
Green
14
Economizer Damper
Control
ECD
NA
16
Outdoor
Temp/Humidity Probe
OT1in
Black
18
Humidifier Output
HUM
NA
19
Outdoor
Temp/Humidity Probe
OT3in
Red
**Note: Brown or Black are the most common
colors for 24VAC ground; however, white and
blue are also frequently used.
24 of 24
Chart 9: Required Wiring for Single Heat
Pump w/ 1 Additional Heater Installations
Chart 10: Optional Wiring for Single Heat
Pump w/ 1 Additional Heater Installations
*
*
*Caution!
While there are some industry-wide
color-coding conventions, some thermostat makers
color-coding conventions, some thermostat makers
do not follow these conventions, so it is imperative to
record the previous configuration (both color and
function) so the correct wire can be connected to the
appropriate location on Comfort Window's wall-plate.