Tank Heater Switch - Bunn CW-APS Operating & Service Manual

SERVICE (cont.)

TANK HEATER SWITCH

FIG. 14 TANK HEATER SWITCH
Location:
The tank heater switch is located on the rear of
the brewer on the upper left side of the trunk.
Test Procedure:
1. Disconnect the brewer from the power source.
2. Disconnect the black wire from the limit thermo-
stat.
3. With the tank heater switch in the "ON"(upper)
position, and with a voltmeter, check the voltage
between the black wire removed from the limit
thermostat and the white wire or red wire on the
tank heater. Connect the brewer to the power
source. The indication must be:
a) 120V volts ac on two wire 120 volt models.
b) 240 volts ac on three wire 120/240 volt mod-
els.
c) 200 to 240 volts ac on 200 volt or 240 volt
models.
d) 100 volts ac for 100 volt models.
4. Disconnect the brewer from the power source.
If voltage is present as described, proceed to #5.
If voltage is not present as described, refer to the
Wiring Diagrams and check the brewer wiring har-
ness.
5. Check for continuity between the black wire re-
moved from the limit thermostat and the black
insert on the terminal block. with the tank heater
switch in the "ON" upper position. Continuity should
not be present in the "OFF" lower position.
If continuity is present as described, the tank heater
switch is operating properly.
If continuity is not present as described, replace the
tank heater switch.
Removal and Replacement:
1. Shut off and disconnect the incoming water sup-
ply to the brewer.
2. On automatic brewers gently remove the fill tube
P1127.40
from back of fill basin.
3. Remove the tank inlet fitting securing fill basin the
tank lid. Remove fill basin and gasket. Set all three
parts aside for reassembly.
4. On brewers with faucets, disconnect the water
supply to coil assembly and remove the tube from
the tank to the faucet.
5. Remove sprayhead and hex nut securing spray-
head tube to the hood. Set aside for reassembly.
6. Disconnect the wires on the limit thermostat and
the tank heater and the control thermostat (early
models).
7. Gently pull the thermostat sensor and grommet
from the tank lid.
8. Insert a tube to the bottom of the tank and syphon
ALL of the water out.
9. Gently reinstall the thermostat sensor and grom-
met in the tank lid.
10. Remove the two #8-32 screws securing the tank
assembly to the hood.
11. Lift tank and components out as an assembly and
set aside for reassembly.
12. Disconnect the two black wires from the tank
heater switch.
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