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WIRING DIAGRAMS
O/B
Changeover
Relay*
* Changeover Relay is energized in COOL when O/B switch is in the "O" position
Changeover Relay is energized in HEAT when O/B switch is in the "B" position
Figure 2. Typical wiring diagram for single transformer single stage systems
NOTE
If safety circuits are in
only one of the systems,
remove the transformer
of the system with NO
safety circuits.
CUT AND
TAPE OFF!
HOT
120 VAC
24 VAC
NEUTRAL
* Changeover Relay is energized in COOL when O/B switch is in the "O" position
Changeover Relay is energized in HEAT when O/B switch is in the "B" position
Figure 3. Typical wiring diagram for two transformer single stage systems with NO safety circuits
Optional Jumper for
Single Stage Heat Pump
O/B
Y
G
Changeover
Fan
Relay*
Relay
Compressor
Contactor
* Changeover Relay is energized in COOL when O/B switch is in the "O" position
Changeover Relay is energized in HEAT when O/B switch is in the "B" position
Figure 4. Typical wiring diagram for two transformer single stage systems with safety circuits in BOTH systems
Optional Jumper for
Single Stage Heat Pump
Y
G
Fan
Compressor
Relay
Heat Relay
Contactor
Optional Jumper for
Single Stage Heat Pump
O/B
Y
G
Changeover
Fan
Relay*
Relay
Compressor
Contactor
W
C
Optional
Heat
Relay
TWO COMMONS MUST
BE JUMPERED TOGETHER!
W
C
Optional
W
C
Optional
Heat Relay
TWO COMMONS MUST
BE JUMPERED TOGETHER!
Polarity must be observed. If the HOT side of the
second transformer is jumpered to the COMMON side
of the first transformer a short will be made. Damage
to equipment will occur when power is restored.
R
Limit or
Safety
Switches
24 VAC
ACCESSORY
RELAY N.O.
CONTACT
COMMON
Limit or
Safety
Switches
24 VAC
COMMON
Heat Pump Transformer
(Class II Current Limited)
3
THERMOSTAT
R
SYSTEM
Hot
24 VAC
120 VAC
Neutral
TRANSFORMER
(Class II Current Limited)
THERMOSTAT
R
SYSTEM
Limit or
Safety
Switches
24 VAC
TRANSFORMER
(Class II Current Limited)
NOTE
THERMOSTAT
SYSTEM
Limit or
Safety
Switches
24 VAC
120 VAC
NEUTRAL
Auxiliary
NOTE
Heating
Transformer
The accessory relay scheme
(Class II
is
required
Current Limited)
circuits exist in both systems.
Limit or
Safety
Switches
HOT
120 VAC
NEUTRAL
Hot
120 VAC
Neutral
HOT
when
safety
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