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Single Stage or Multi-Stage System (No Heat Pump) with Single Transformer
TYPICAL WIRING 1F95-0671
TYPICAL WIRING DIAGRAMS
Single
Stage 1
(SS1)
Multi-
Stage 2
(MS2)
O
Energized Constantly
in
Cool Mode
B
Energized Constantly
in Heat, Off,
Emergency
Mode
No
Output
Cool
Mode
2nd
Stage
Cool Mode
1st Stage
Blower/
Circulator
Fan Energized
on Call for
Cool (and
Heat if
configured
for Electric
Heat)
No Output
Heat Mode
2nd Stage
Heat
Mode
1st Stage
Optional*
24 Volt
(Com-
mon)
24 Volt
(Hot)
Cool
System
Y G W/E C L RC
CLASS II
TRANSFORMER
HOT
24VAC
NEUTRAL
120VAC
24 Volt
(Hot)
Heat
RH Y2 W2
Jumper
Diagnostic
Indicator
Input
or
System
Malfunction
Switch
Input
Comfort Alert II Module
or Similar System
Diagnostic Module
See Module Instructions
for details
O/B
* Common connection required for diagnostic or malfunction indication.
Single Stage or Multi-Stage System (No Heat Pump) with Two Transformers
Single
Stage 1
(SS1)
Multi-
Stage 2
(MS2)
No
Output
Cool
Mode
2nd
Stage
Cool Mode
1st Stage
Blower/
Circulator
Fan Energized
on Call for
Cool (and
Heat if
configured
for Electric
Heat)
No Output
Heat Mode
2nd Stage
Heat
Mode
1st Stage
Optional
24 Volt
(Com-
mon)
Diagnostic
Indicator
(Optional)
24 Volt
(Hot)
Cool
System
Y G W/E C L RC
CLASS II
TRANSFORMER
HOT
24VAC
NEUTRAL
120VAC
24 Volt
(Hot)
Heat
RH
120VAC
Remove Jumper Wire
between RH & RC
HOT
24VAC
NEUTRAL
CLASS II
TRANSFORMER
HEATING
COOLING
Y2 W2
Jumper
O/B
O
Energized Constantly
in
Cool Mode
B
Energized Constantly
in Heat, Off,
Emergency
Mode
Heat Pump Systems
Heat Pump 1
(HP1)
Heat Pump 2
(HP2)
O
Energized in
Cool Mode
B
Energized in
Heat, Off,
Emergency
Mode
No
Output
2nd
Stage
(Com-
pressor)
Heat and
Cool Mode
1st Stage
(Compressor)
Blower/
Circulator Fan
Energized on
Call for Heat
or Cool.
Set Elect/Gas
Option for
Emergency
mode
Heat Mode - 3rd
Stage, Emergency
Mode - 2nd Stage
Heat Mode-4th
Stage. Emergency
Mode - 2nd Stage
Heat Mode - 2nd
Stage, Emergency
Mode - 1st Stage
Heat Mode - 3rd
Stage, Emergency
Mode - 1st Stage
Optional*
24 Volt
(Com-
mon)
Diagnostic
Indicator
or System
Malfunction
Switch
24 Volt
(Hot)
Cool
System
Y + W/E C L RC
CLASS II
TRANSFORMER
HOT
24VAC
NEUTRAL
120VAC
24 Volt
(Hot)
Heat
RH
Jumper
Y2 + W2 G
Comfort Alert II Module
or Similar System
Diagnostic Module
See Module Instructions
for details
O/B
+Note: Dual Fuel option
de-energizes Heat mode
stage 1 (compressor)
when auxiliary heat
is energized
+ Note: Dual Fuel option
de-energizes Heat mode
stage 1 (compressor)
when auxiliary heat
is energized
+Note: Dual Fuel option
de-energizes Heat mode
stage 1 (compressor)
when auxiliary heat
is energized
+ Note: Dual Fuel option
de-energizes Heat mode
stage 1 (compressor)
when auxiliary heat
is energized
* Common connection required for diagnostic or malfunction indication.
+ Dual Fuel option, if selected turns off compressor(s) when Auxiliary stages energize.
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