Bunn FMD-4 User Guide

38

Removal and Replacement:

1.  Disconnect the dispenser from the power source.

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

3.  Disconnect  the  black    wires  on  the  limit  therm-

stat.

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 

and the green wire from the tank.

6.  Remove  the  thermostat  capillary  bulb  by  firmly 

pulling-up on the capillary at the tank lid. This will 

disengage the grommet from the tank lid.

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

the tank.

8.  Remove tank lid with limit thermostat, liquid level 

probe and tank heater as an assembly.

9.  Remove the two hex nuts securing the tank heater 

to the tank lid. Remove tank heater with gaskets 

and discard.

10. Install new tank heater with gaskets on the tank lid 

and secure with two hex nuts.

11. Install  tank  lid  with  limit  thermostat,  liquid  level 

probe and tank heater on the tank and secure with 

ten #8-32 hex nuts.

12. Connect water inlet line to the tank lid.

13. 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 reconnecting wires.

14. Refer to Fig. 36 when reconnecting the wires to the 

tank heater.

FIG. 36 TANK HEATER TERMINALS

P1218

WHI or RED to

Main Harness

BLK to Limit

Thermostat

FIG. 35 TANK HEATER

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.  Check the voltage across the black and white wires 

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

volt  models or 120/240 volt models with a voltme-

ter. 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.

 

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 termi-

nals.

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.

P2635

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