System
O
RH
+
B
CLASS II
TRANSFORMER
HOT
24VAC
NEUTRAL
120VAC
W/E
G
C
-
W2
No
Output
24 V A C
(Hot)
Cool
DC
supply
voltage
to re-
mote
Temp-
erature
Sensor
Remote
Temp-
erature
Sensor
signal
DC
Return
to
Remote
T e mp-
erature
Sensor
Y2 Y
RC
S
6
L
{
T o Remote T e mperature Sensor
24 V A C
(Hot)
Heat
24 V A C
Com-
mon
(option-
al) *
CLASS II
TRANSFORMER
120VAC
HOT
24VAC
NEUTRAL
HEATING
COOLING
Ener-
gized
in Heat
Mode
Energiz-
ed in
Cool &
Off
Mode
Cool
mode
2nd
Stage
(Com-
pressor)
Cool
Mode
1st
Stage
(Com-
pressor)
Blower/
Circula-
tor Fan
Energiz-
ed on
call for
Cool &
for Heat
(if ELE
is sel-
ected)
Heat
Mode
2nd
Stage
No
Output
Heat
Mode
1st
Stage
Ener-
gized
on call
for
Heat
Power
Closed
Conn-
ection
for
3-wire
zone
valve
Fault
Indicator
or
System
Malfunc-
tion
Switch
Single
Stage 1
(SS1)
Multi-
Stage 2
(MS2)
Comfort
Alert II module
or similar
malfunction
module
Single
Stage 1
(SS1)
Multi-
Stage 2
(MS2)
Energiz-
ed in
Cool &
Off
Mode
Ener-
gized
in Heat
Mode
System
O
RH
+
B
CLASS II
TRANSFORMER
HOT
24VAC
NEUTRAL
120VAC
W/E
G
C
-
W2
Jumper
No
Output
Cool
Mode
1st
Stage
(Com-
pressor)
Blower/
Circula-
tor Fan
Energiz-
ed on
call for
Cool &
for Heat
(if ELE
is sel-
ected)
24 V A C
(Hot)
Cool
DC
supply
voltage
to re-
mote
T e mp-
erature
Sensor
Remote
Temp-
erature
Sensor
signal
DC
Return
to
Remote
T e mp-
erature
Sensor
Heat
Mode
1st
Stage
Power
Closed
Conn-
ection
for
3-wire
zone
valve
Fault
Indicator
or
System
Malfunc-
tion
Switch
Y2 Y
RC
S
6
L
{
T o Remote T e mperature Sensor
Cool
mode
2nd
Stage
(Com-
pressor)
24 V A C
(Hot)
Heat
24 V A C
Com-
mon
(option-
al) *
Heat
Mode
2nd
Stage
No
Output
Ener-
gized
on call
for
Heat
Comfort
Alert II module
or similar
malfunction
module
Heat
Pump 1
(HP1)
Heat
Pump 2
(HP2)
Energiz-
ed in
Cool
& Off
Mode
Energiz-
ed in
Heat/
Emer-
gency
Mode
System
O
RH
+
B
CLASS II
TRANSFORMER
HOT
24VAC
NEUTRAL
120VAC
W/E
Jumper
G
C
-
W2
Jumper
No
Output
1st
Stage
Heat &
Cool
(Com-
pressor)
**
Blower/
Circula-
tor Fan
Energiz-
ed on
call for
Heat or
Cool
24 V A C
(Hot)
Cool
DC
supply
voltage
to re-
mote
T e mp-
erature
Sensor
Remote
Temp-
erature
Sensor
signal
DC
Return
to
Remote
T e mp-
erature
Sensor
Auxil-
iary &
Emer-
gency
Heat
1st
Stage
Power
Closed
Conn-
ection
for
3-wire
zone
valve
Fault
Indicator
or
System
Malfunc-
tion
Switch
Y2 Y
RC
S
6
L
{
T o Remote T e mperature Sensor
2nd
Stage
Heat/
Cool
(Com-
pressor)
24 V A C
(Hot)
Heat
24 V A C
Com-
mon
(option-
al) *
(Dual
Fuel
disabled)
Emer-
gency
heat
2nd stage
(Dual
Fuel
enabled)
Auxiliary
& Emer-
gency
heat
2nd stage
Comfort
Alert II module
or similar
malfunction
module
www.white-rodgers.com
Big Blue Universal Thermostat
Wiring Diagrams for 1F95-1277
PART NO. 37-6808D
Replaces 37-6808C
0904
Single Stage, Multi-Stage, Heat Pump
White-Rodgers is a division
of Emerson Electric Co.
www.white-rodgers.com
Printed In U.S.A.
Heat Pump Connections
If you do not have a heat pump system, refer to gures 2 & 3.
Refer to equipment manufacturers' instructions for specic system
wiring information.
You can congure the thermostat for use with the following heat
pump systems.
HEAT PUMP TYPE 1 (HP 1). Single stage compressor system; gas
or electric backup.
HEAT PUMP TYPE 2 (HP 2). Multi-stage compressor or two com-
pressor system with gas or electric backup.
After wiring, see INSTALLER CONFIGURATION section for proper
thermostat conguration.
NOTE: If your system does not
provide an E connection, jumper W2
to W/E to use the Auxiliary Heat in the
Emergency Mode.
* 24 VAC common connection
optional for system operation.
Required for fault or malfunction indi-
cation, remote temperature sensor, or
for continuous backlight operation.
** Dual fuel option de-energizes
compressor when auxiliary heat is
energized.
Figure 1 – Heat Pump Systems
Single Stage and Multi-Stage Connections
Refer to equipment manufacturers' instructions for specic system
wiring information.
This thermostat is designed to operate a single-transformer or two-
transformer system.
You can congure the thermostat for use with the following fossil fuel
systems:
SINGLE STAGE (SS 1) gas, oil or electric.
MULTI-STAGE (MS 2) gas, oil or electric.
After wiring, see INSTALLER CONFIGURATION section for proper
thermostat conguration.
Figure 2 – Single Stage or Multi-Stage System (No Heat Pump) with Single Transformer
Figure 3 – Single Stage or Multi-Stage System (No Heat Pump) with Two Transformers
* 24 VAC common connection
optional for system operation.
Required for fault or malfunc-
tion indication, remote temper-
ature sensor, or for continuous
backlight operation.
NOTE: If continuous backlight or hardwired
power input are desired but do not function
in both HEAT and COOL modes, cut the
heating transformer 24V wires and tape off.
Connect the neutral circuit disconnected
from the heating transformer to the neutral
circuit of the cooling transformer. Discon-
nect the wire to the RH terminal and install
a jumper between RH and RC. Depending
on the system requirements, replace the
cooling transformer with a 75VA class II
transformer if needed.
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