Switch C is active ONLY on heat pump and 2-speed models.
When set to ON (AC only), output O/W2 becomes a second-stage
heat output, allowing the thermostat to control 2-stage heating
equipment. When set to OFF for heat pump operation, O/W2 is
energized during cooling for reversing valve control.
Switch D - Staging Select (Active on 2S models only)
Set switch D to ON only for special 3-stage electric heat with
single-speed heat pump. (See Fig. 14.) Set to OFF for standard
1-stage electric heat with 2-speed heat pump. (See Fig. 13.)
When using the 2-speed thermostat model with a single-speed heat
pump, the low speed output becomes a second-stage auxiliary heat
output (Y1/W2 terminal). In addition, the auxiliary heat output
sequence is: 1st stage = W/W1 only; 2nd stage = Y1/W2 only; 3rd
stage = W/W1 and Y1/W2. Special 2-stage heaters with 1:2
capacity ratio provide 3 equal stages of auxiliary heat. Only the
FK4B fan coil may be used in this application.
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
terminal marking.
d. Discard or recycle old thermostat.
NOTE:
Mercury is a hazardous waste and MUST be disposed of
properly.
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.
Allow an extra 10 to 12 in. of wire for connection to terminals.
Remove outer sheath over this entire length for added flex-
ibility.
5. Level mounting base against wall and mark wall through 2
mounting holes.
6. Drill two 3/16-in. mounting holes in wall where marked.
7. Secure mounting base to wall with 2 screws and anchors
provided, making sure all wires extend through mounting
base.
8. Adjust wire length and routing to allow proper closure of
thermostat. Strip each wire end no more than 1/4 in. to prevent
adjacent wires from shorting together. Match and connect
equipment lead wires to the correct terminals of the thermostat
connector. (See Table 1 and Fig. 2 through 14.) 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 excess wiring into wall. Seal hole in wall to prevent
drafts.
10. Snap hinge back together.
11. Close thermostat door.
12. Turn ON power to unit.
On power up, LCD readout shows selected setup mode AC, HP,
A2, H2, or HS for a few seconds depending on model and dip
switch settings.
Step 4—Set Thermostat Configuration
Two configuration options are available for the thermostat.
Fahrenheit/Celsius Selection
Thermostat displays actual room temperature and desired room
temperature in Fahrenheit or Celsius. Thermostat is factory set to
Fahrenheit.
Anticipator Adjustment
Thermostat is factory set to an anticipator value of 3. Anticipator
value can be adjusted between 1 and 9, with smaller numbers
increasing equipment cycling and larger numbers decreasing
equipment cycling. Maximum cycle rate is limited to 4 cycles per
hr.
To enter the configuration mode:
1. Press and hold FAN button for approximately 10 sec until
room temperature disappears and LCD readout reads "--".
NOTE:
If no button is pressed for 10 sec, thermostat will exit
mode and resume normal operation. To re-enter configuration
mode, FAN button must be pressed and held again.
2. Press the RESET FILTER button to display an F for Fahren-
heit or a C for Celsius.
NOTE:
Thermostat is factory set to Fahrenheit. If Celsius con-
figuration is desired, press up or down button once so LCD readout
shows C.
3. Press MODE button to display anticipator value, factory set at
3.
4. Press up or down button to select desired anticipator value.
Step 5—Hold, Fan, Mode Button Operation
1. Pressing HOLD button disables the time/temperature schedule
and
″
holds
″
the current desired temperature. When active, the
HOLD annunciator is turned on. A second press of the HOLD
button releases the hold feature and turns off the annunciator.
Table 1—Model Selection and Wiring Diagram Chart
OUTDOOR
UNIT
AIR CONDITIONER
HEAT PUMP
1 Speed
2 Speed
1 Speed
2 Speed
1-Stage
Furnace
Model AC
See Fig. 2
Model 2S
See Fig. 8
Requires
Interface Control
Model 2S
See Fig. 11
2-Stage
Furnace
Model AC
See Fig. 3
Model HP
See Fig. 4
Model 2S
See Fig. 9
Requires
Interface Control
Model 2S
See Fig. 12
Fan Coil
Model AC
See Fig. 5
Model HP
See Fig. 6
Model 2S
See Fig. 10
Model HP
See Fig. 7
Model 2S
See Fig. 13
FK4B
Fan Coil
Model 2S
See Fig. 14
2
