Control Thermostat - Bunn OT Operating & Service Manual

Part II
SERVICE (cont.)

Control Thermostat

FIG. 6 CONTROL THERMOSTAT
Location:
The control thermostat is located behind the front
panel, FIG. 6 to the left of the tank.
To test the control thermostat, access will also
be needed to the tank heater located in the top of the
brewer.
Test Procedure:
1. Disconnect the brewer from the power source.
2. Check the voltage across the blue wire on the
control thermostat and the white or red wire on
the tank heater with a voltmeter. Connect the
brewer to the power source. The indication must
be:
a) 120 volts ac for two wire 120 volt models.
b) 200 or 240 volts ac for two wire 200 volt or
240 volt models and three wire 120/240 volt
models.
c) 100 volts ac for two wire 100 volt models.
3. Disconnect the brewer from the power source.
If voltage is present as described, proceed to #4.
If voltage is not present as described, refer to the Wir-
ing Diagrams and check the brewer wiring harness.
4. Check the voltage across the black wire terminal
of the control thermostat and the white or red
wire on the tank heater with a voltmeter when
the control thermostat is turned "ON" (fully
clockwise). Connect the brewer to the power
source. The indication must be as described in
step 2. Voltage must not be indicated across
these terminals when the thermostat is turned
"OFF" (fully counterclockwise).
5. Disconnect the brewer from the power source.
If voltage is present as described, the control thermo-
stat is operating properly.
If voltage is not present as described, replace the
control thermostat.
Removal and Replacement:
1. Remove both wires from the control thermostat
terminals.
2. Remove the top lid from the brewer to gain access
to the thermostat bulb.
3. Remove the thermostat bulb by firmly pulling-
up on the capillary tube at the tank lid. This will
disengage the grommet from the tank lid.
4. Remove the two #8-32 screws holding the control
thermostat to the bracket.
5. Fasten the new control thermostat to the brewer
housing.
P1689
6. Route the capillary tube up though the brewer
trunk.
NOTE - Make sure that the capillary tube is away from
any electrical termination and is not kinked.
7. Slide the grommet to the red mark on the capillary
tube.
8. Insert the bulb through the hole in the tank lid
and press the grommet firmly and evenly so that
the groove in the grommet fits into the tank lid.
9. Carefully bend the capillary tube so that the tube
and bulb inside the tank are in a vertical posi-
tion.
10. Refer to FIG. 7 when reconnecting the wires.
11. Readjust the control thermostat dial as re-
quired.
Page 16
BLU to Limit Thermostat
BLK to Tank Heater
FIG. 7 THERMOSTAT WIRING
P1098
32440 070700