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4
MOUNTING AND WIRING
CONTINUED FROM PAGE 2
CUT AND
TAPE OFF!
HOT
120 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
** Jumper required to use a single Aux Heat for both Second Stage Heat and Emergency
Figure 3. Typical wiring diagram for two transformer heat pump systems with NO safety circuits
O/B/Y2
Changeover
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
** Jumper required to use a single Aux Heat for both Second Stage Heat and Emergency
Figure 4. Typical wiring diagram for two transformer heat pump systems with safety circuits in BOTH systems
O/B/Y2
Y1
Changeover
Fan
Relay*
Compressor
Relay
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
** Jumper required to use a single Aux Heat for both Second Stage Heat and Emergency
Figure 2. Typical wiring diagram for single transformer heat pump systems
If safety circuits are in only one of the systems, remove
the transformer of the system with NO safety circuits.
O/B/Y2
Y1
Changeover
Relay*
24 VAC
Compressor
Contactor
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.
E/W1
Y1
G
W2
See Note **
Fan
Emergency
Relay
Relay
Aux
Relay
(Stage 2)
TWO COMMONS MUST
BE JUMPERED TOGETHER!
E/W1
G
W2
See Note **
Emergency
Aux
Relay
Relay
(Stage 2)
NOTE
E/W1
G
W2
See Note **
Fan
Emergency
Relay
Relay
Aux
Relay
(Stage 2)
TWO COMMONS MUST
BE JUMPERED TOGETHER!
NOTE
C
L
R
SYSTEM
MONITOR
SWITCH
Limit or
Safety
Switches
COMMON
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THERMOSTAT
C
L
R
SYSTEM
SYSTEM
MONITOR
SWITCH
Hot
24 VAC
120 VAC
Neutral
TRANSFORMER
(Class II Current Limited)
THERMOSTAT
C
L
R
SYSTEM
SYSTEM
Limit or
MONITOR
Safety
SWITCH
Switches
24 VAC
TRANSFORMER
(Class II Current Limited)
THERMOSTAT
SYSTEM
Limit or
Safety
Limit or
Switches
Safety
24 VAC
120 VAC
Switches
24 VAC
Auxiliary
ACCESSORY
Heating
RELAY N.O.
Transformer
The accessory relay scheme
CONTACT
(Class II
is
required
Current Limited)
circuits exist in both systems.
COMMON
Limit or
Safety
Switches
24 VAC
120 VAC
NEUTRAL
Heat Pump Transformer
(Class II Current Limited)
Hot
120 VAC
Neutral
HOT
NEUTRAL
NOTE
when
safety
HOT
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