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Wiring
1.
If you are replacing a thermostat, make
note of the terminal connections on the
thermostat that is being replaced. In some
cases the wiring connections will not be
color coded. For example, the green wire
may not be connected to the G terminal.
2.
Loosen the terminal block screws. Insert
wires then retighten terminal block screws.
3.
Place nonflammable insulation into wall
opening to prevent drafts.
Terminal Designations
This thermostat is shipped from the factory to operate a conventional heating and cooling system. This thermostat will
also operate a heat pump system. See the "heat pump" configuration step on page 8 of this manual to configure the
thermostat for heat pump applications.
2 Heat 2 Cool
Terminal
Conventional System
Transformer power
RC
(cooling)
Transformer power
RH
(heating)
Transformer common
C
Energized in heating
B
Energized in cooling
O
Fan relay
G
First stage of heat
W/E
Y
First stage of cool
Y2
Second stage of cool
W2
Second stage of heat
PRO1 Tips:
C terminal
The C (common wire) terminal does not
have to be connected when the thermostat is
powered by batteries.
Wire specifications
Use shielded or non-shielded
18 - 22 gauge thermostat wire.
2 Heat 2 Cool
Heat Pump System
Transformer power
(cooling)
Transformer power
(heating)
Transformer common
Heat pump changeover valve
energized in heating
Heat pump changeover valve
energized in cooling
Fan relay
Emergency heat relay
First stage of heat & cool
Second stage of cool
Auxiliary heat relay,
second stage of heat
Note:
In many systems with no emergency
heat relay a jumper can be installed
between E and W2.
Warning:
All components of the control
system and the thermostat
installation must conform to
Class II circuits per the NEC Code.
3 Heat 2 Cool
Heat Pump System
Transformer power
(cooling)
Transformer power
(heating)
Transformer common
Heat pump changeover valve
energized in heating
Heat pump changeover valve
energized in cooling
Fan relay
Emergency heat relay
First stage of heat & cool
Second stage of cool
& second stage of heat
Auxiliary heat relay,
third stage of heat
WIRING
5
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