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2
Mounting
Hole
Mounting
Hole
Place Level
across
Mounting Tabs
(for appearance only)
Y2
W/E
W2
Place Level
across
Mounting Tabs
(for appearance only)
2 "AA" Batteries
WIRING CONNECTIONS
Refer to equipment manufacturers' instructions for specific
system wiring information. After wiring, see CONFIGURA-
TION section for proper thermostat configuration.
For wiring diagrams, see 37-6740A.
Wiring diagrams shown are for typical systems and describe
the thermostat terminal functions.
WARNING
!
Thermostat installation and all components of the
control system shall conform to Class II circuits per
the NEC code.
INSTALLATION
Battery Location
2 "AA" alkaline batteries are included in the thermostat at
the factory with a battery tag to prevent power drainage.
Remove the battery tag to engage the batteries.
To replace batteries, set system to OFF, remove thermostat
from wall and install the batteries in the rear along the top of
the thermostat (see Figure 1).
Figure 1 – Thermostat base and rear view of thermostat
Remove Old Thermostat
A standard heat/cool thermostat consists of three basic parts:
1. The cover, which may be either a snap-on or hinge type.
2. The base, which is removed by loosening all captive screws.
3. The switching subbase, which is removed by unscrewing
the mounting screws that hold it on the wall or adapter
plate. Before removing wires from old thermostat,
label each wire with the terminal designation from
which it was attached. Disconnect the wires from the old
thermostat one at a time. Do not let wires fall back into
the wall.
Installing New Thermostat
1. Pull the thermostat body off the thermostat base. Forcing
or prying on the thermostat will cause damage to the unit.
2. Place base over hole in wall and mark mounting hole
locations on wall using base as a template.
3. Move base out of the way. Drill mounting holes. If you
are using existing mounting holes and the holes drilled
are too large and do not allow you to tighten base snug-
ly, use plastic screw anchors to secure the base.
4. Fasten base snugly to wall using mounting holes shown
in Figure 1 and two mounting screws. Leveling is for
appearance only and will not affect thermostat operation.
5. Connect wires to terminal block on base using
appropriate wiring schematic (see diagram sheet
37-6740A).
Terminal Designation Description
L . . . . . . . . . . . . . . . . Heat pump malfunction indicator for
systems with malfunction connection
O . . . . . . . . . . . . . . . . Changeover valve for heat pump energized
constantly in cooling
B . . . . . . . . . . . . . . . . Changeover valve for heat pump energized
constantly in heating
Y . . . . . . . . . . . . . . . . Compressor Relay
Y2 . . . . . . . . . . . . . . . 2nd Stage Compressor
W/E . . . . . . . . . . . . . . . Heat Relay/Emergency Heat Relay (Stage 1)
W2 . . . . . . . . . . . . . . . 2nd Stage Heat (3rd Stage Heat in HP2)
G . . . . . . . . . . . . . . . . Fan Relay
RH . . . . . . . . . . . . . . . Power for Heating
RC . . . . . . . . . . . . . . . Power for Cooling
C . . . . . . . . . . . . . . . . Common wire from secondary side of cooling
system transformer or heat only system transformer
2
6. Push excess wire into wall and plug hole with a fire re-
sistant material (such as fiberglass insulation) to prevent
drafts from affecting thermostat operation.
7. Carefully line the thermostat up with the base and snap
into place.
TERMINAL DESIGNATION DESCRIPTIONS