• Close to or in a frequently used room, preferably on an inside
• On a section of wall without pipes or duct work.
Thermostat should NOT be mounted:
• Close to a window, on an outside wall, or next to a door leading
to the outside.
• Exposed to direct light and heat from a lamp, sun, fireplace, or
other temperature-radiating object which may cause a false
• Close to or in direct airflow from supply registers and return-air
• In areas with poor air circulation, such as behind a door or in
Step 2—Set DIP Switches
There is a 4 section DIP switch within the thermostat which must
be properly set by the installer. It is easiest to set these 4 switches
before the thermostat is mounted to the wall, so STOP and
complete the following steps:
1. Open hinged thermostat cover.
2. Remove cover completely by snapping it apart at hinge.
3. Open thermostat by pressing back half of the right end of
plastic case inward while, at the same time, pulling front and
back halves apart at the right end. The 2 halves will swing
4. Snap hinge apart to completely separate the 2 halves.
5. Switches are located in upper right corner of circuit board. To
change switch position, use corner of a small screwdriver to
slide switch to opposite position.
6. After switches have been set, do not reassemble the 2 halves.
The rear plastic will be first mounted to wall.
Switch A - Zoning Select (Active on all models)
This switch selects or defeats the 4 cycles per hour limit and a
5-minute compressor timeguard. These timers MUST be enabled
for normal operation and disabled for zoning applications. (In
zoning applications the zone control center performs these timing
OFF— for normal operation. This is the factory default.
ON—for zoned installations ONLY.
Switch B - Setback Recovery (Active on all models)
Selects between normal and smart recovery from setback. Normal
recovery changes to the new setpoint at the programmed time.
Smart recovery, which is active in heating mode only, starts earlier
and adjusts the setpoint slowly so that room temperature will arrive
at the programmed temperature at the programmed time.
OFF—for smart recovery. This is the factory default.
ON—for normal recovery.
Switch C - HP/AC Select (Active on HP and 2S models only)
Use to select between AC and HP installations. HP and 2S models
have an extra relay to control the HP reversing valve. When a HP
thermostat is placed in the AC mode, this extra relay is converted
to a second stage heat output. This allows thermostat control of
2-stage furnaces or 2-stage strip heat with AC systems. (AC mode
also uses W rather than Y for first-stage heat.)
OFF—for HP applications. Extra relay controls reversing valve.
This is factory default.
ON—for AC applications. Extra output can be used for 2-stage
Switch D - Intelligent Heat Staging Select
(Active on 2S models only)
This switch converts a 2-speed heat pump thermostat with 1 stage
of auxiliary heat into a 1-speed heat pump thermostat with 3 stages
of auxiliary heat for comfortable leaving air temperature. It
requires selected heaters with 2:1 ratio element sizes plus an FK,
FV, 40FKA fan coil. Refer to variable-speed fan coil literature for
OFF—for normal 2-speed operation. This is factory default.
ON—for intelligent 3-stage heat with FK, FV, 40FKA fan coil.
Step 3—Install Thermostat
Before installing thermostat, turn off all power to unit. There
may be more than 1 power disconnect. Electrical shock can
cause personal injury or death.
1. Turn OFF all power to unit.
2. If an existing thermostat is being replaced:
a. Remove existing thermostat from wall.
b. Disconnect wires from existing thermostat, 1 at a time. Be
careful not to allow wires to fall back into the wall.
c. As each wire is disconnected, record wire color and
d. Discard or recycle old thermostat.
NOTE: Mercury is a hazardous waste and MUST be disposed of
3. Open thermostat rear door (mounting base) to expose mount-
ing holes. The base can be removed to simplify mounting.
Snap apart carefully at hinge to separate mounting base from
remainder of thermostat.
4. Route thermostat wires through large hole in mounting base.
Level mounting base against wall (for aesthetic value
only—thermostat need not be leveled for proper operation)
and mark wall through 2 mounting holes.
5. Drill two 3/16-in. mounting holes in wall where marked.
6. Secure mounting base to wall with 2 screws and anchors
provided, (additional anchoring holes available for more
secure mounting if needed) making sure all wires extend
through hole in mounting base.
7. Adjust length and routing of each wire to reach proper
terminal and connector block on mounting base with 1/4 in. of
extra wire. Strip only 1/4 in. of insulation from each wire to
prevent adjacent wires from shorting together when con-
8. Match and connect equipment wires to proper terminals of the
connector blocks. (See Table 1, and Fig. 2 through 24.) Both
R and C must be connected for proper thermostat operation.
Improper wiring or installation may damage the thermostat.
Check to make sure wiring is correct before proceeding with
installation or turning on unit.
9. Push any excess wire into wall and against mounting base.
Seal hole in wall to prevent air leaks. Leaks can affect
10. Snap hinge back together.
11. Close thermostat assembly making sure pins on back of circuit
board align with sockets in connector.