7
69-0750—1
THERMOSTAT
This thermostat was calibrated at the factory and should
not need recalibration in the field. If recalibration seems
necessary, first be sure wallplate or subbase is accurately
leveled. Then check thermometer calibration.
To check thermostat calibration, allow several hours of
operation after installation. Then read the thermometer and
remove the cover. Push the temperature levers together to a
setting the below room temperature. Slowly move them up
the scale together until the mercury slides across the tube.
IF THE THERMOMETER READING AND THE HIGH
TEMPERATURE LEVER POSITION ARE APPROXI-
MATELY THE SAME AT THE INSTANT THE MER-
CURY MOVES TO THE OTHER END, NO
RECALIBRATION IS NEEDED.
If calibration is necessary, proceed as follows:
1. Remove the cover.
2. Place open-end calibration wrench, part no. 104994A
(ordered separately), on the hex nut under the bimetallic coil
controlled by the red lever. See Fig. 14. Hold lever so it does
not move, and gently turn the wrench clockwise until
the mercury rests securely in the right end of the tube.
3. Put the thermostat cover on and wait ten minutes.
4. Read the thermometer. Then remove the cover. Mov-
ing both levers, place the HIGH lever at the thermometer
reading. Hold lever so it does not move, and gently turn the
wrench counterclockwise until the mercury just slides
to the left end of the tube but no farther. Try to do this quickly
so the heat from your hands does not affect the thermostat.
5. Repeat this procedure for the blue lever.
If thermostat fails any test, refer to the Troubleshooting
Guide in the Owner’s Manual.
Reset both temperature setting levers to the desired
temperatures.
HEATING/COOLING SYSTEM
Turn on power to the furnace and cooling system.
Place the system switch lever to HEAT and fan switch
lever to AUTO.
Push both temperature setting levers together at least
5
°
F [3
°
C] above room temperature. The main burner
should come on. The fan will start when the furnace heats
up. (If central electric heat, fan coil or heat pump system,
fan starts immediately.)
5. If the readings are different, insert a small screwdriver
in the thermometer and turn it until the thermometers have
the same reading. See Fig. 13.
6. Replace the thermostat cover and put the system into
operation.
NOTE: Radiant heat from your hands will offset the ther-
mometer reading. After making each adjustment, wait
five or ten minutes for the thermometer to stabilize before
comparing.
Fig. 13—Thermometer calibration.
Move both levers 5
°
F [3
°
C] below room temperature.
The burner should shut off.
Place the system switch lever to COOL and the fan
switch lever to AUTO. The cooling equipment will oper-
ate, and the fan will start. Allow for any time delay that may
be built into the compressor control circuit.
NOTE: To avoid compressor damage, do not operate the
system when outdoor temperature is below 50
°
F [10
°
C].
Refer to manufacturer recommendations.
Move together both temperature setting levers at least
5
°
F [3
°
C] above room temperature. The cooling equip-
ment should shut off.
Place the fan switch to ON. The fan should run continu-
ously with the system switch in any position.
Place the system switch to OFF. Move both temperature
setting levers to various positions. The heating and cooling
systems should not operate.
Operate the entire system for at least one complete cycle
with the system switch at COOL and one complete cycle
with the switch at HEAT.
If thermostat fails any test, refer to the Troubleshooting
Guide in the Owner’s Manual.
Reset both temperature setting levers to the desired
temperatures.
Leave Owner’s Manual and assistance information in a
convenient place for the building occupant or provide with
other appliance manuals.
Calibration
THERMOMETER
The thermometer in your thermostat was accurately
calibrated at the factory. The thermometer should need
adjustment only if it has been dropped or shifted due to
mishandling. If the setpoint lever and the thermometer
reading do not agree:
1. Remove the thermostat cover by pulling up from the
bottom of cover until it clears the mounting slots.
2. Set the thermostat cover on a table near an accurate
thermometer.
3. Allow five minutes for cover thermometer to sense
area temperature; compare the readings. Be careful not to
touch thermometer or breathe on it.
4. If the readings are the same, replace the cover and put
the system into operation.
M5128
INCREASE