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