Bunn FMD-5 User Manual

50

FIG. 50 TANK HEATER

P4102.40

Location:
The tank heater is located inside the tank and secured to 

the tank lid.

Test Procedure:

1.  Disconnect the dispenser from the power source.

2.  With a voltmeter check the voltage across the black 

and white wires 120 volt or 240 volt models or black 

and red wires for 120/208 volt  models or 120/240 volt 

models. Connect the dispenser to the power source. 

The indication must be:

 

a) 120 volts ac for two wire 120 volt models;

 

b) 208 volts ac for three wire 120/208 volt models.

 

c) 240 volts ac for three wire 120/240 volt models and 

two wire 240 volt models.

 

d) 230 volts ac for two wire 230 volt models.

3.  Disconnect the dispenser from the power source.

If voltage is present as described, proceed to #4.

If voltage is not present as described, refer to the dispenser 

wiring diagram and check the wiring harness.

4.  Disconnect the black wire and the white or red  wire 

from the tank heater terminals.

5.  Check for continuity across the tank heater terminals.

If continuity is present as described, reconnect the wires, 

the tank heater is operating properly.

If continuity is not present as described, replace the tank 

heater.

NOTE - If the tank heater remains unable to heat, remove 

and inspect heater for cracks in the sheath.

Removal and Replacement:

1.  Shut off water supply to the dispenser.

2.  Disconnect the water supply tube on the tank lid.

3.  Disconnect the black wires on the limit thermostat.

FIG. 51 TANK HEATER TERMINALS

P1218

WHI or RED to Main 

Wiring Harness

BLK to Limit 

Thermostat

4.  Disconnect the black wire and the white or red wire from 

the tank heater terminals.

5.  Disconnect the pink wire from the liquid level probe.

6.  Disconnect the green wire from the tank.

7.  Remove the thermostat capillary bulb/temperature probe 

by firmly pulling up on the capillary at the tank lid. This 

will disengage the grommet from the tank lid.

8.   Remove the ten #8-32 nuts securing the tank lid to the 

tank.

9.  Remove tank lid with limit thermostat, liquid level probe 

and tank heater as an assembly.

10. Remove the two hex nuts securing the tank heater to 

the tank lid. Remove tank heater with gaskets and dis-

card.

11.  Install new tank heater with gaskets on the tank lid and 

secure with two hex nuts.

12. Install tank lid with limit thermostat, liquid level probe 

and tank heater on the tank and secure with ten #8-32 

hex nuts.

13.  Connect water inlet line to the tank lid.

14.  Reconnect the black wires to limit thermostat,  the pink 

wire to the liquid level probe and the green wire to the 

tank. Refer to the limit thermostat and the liquid level 

board and probe sections in this manual when recon-

necting wires.

15.  Refer to Fig. 51 when reconnecting the wires to the tank 

heater.

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