Step 1. Remove outer jacket door.
Step 2. Disconnect wire le ads from resettable thermal swit ch.
Step 3. Using a multimeter capable of measuring continuity (Ohms),
place one probe of meteron one of the brassconnection tabs of
the resettable thermal switch, andthe remaining probe on the
other connection tab.
Step 4. If continuity is indicated, the switch is closed, allowing millivolt current to pass.
Step 5. If continuity is not indicated, the switch is open, possibly due to an over heating condition. The switch is
designed to open at predetermined temperatures depending on model. An openswitch can be reset by
depressing the red colored button located at the center of the switch. The overheating condition mustbe
determined prior to putting the h eater back in service.
RESETTABLE THERMAL SWITCH CONTINUITY TESTING
PROBABLE CAUSEFOR RESETTABLE THERMAL SWITCH ACTIVATION
PROBABLECAUSE CORRECTIVE ACTION
Insufficient combustion air
1. Verifyadequate combustionair supply is
available.
2. Clear jacket slotopenings of any dirt, dust,
restrictionsorother obstructions.
3. inspect flame arrestor plate and clean with
stiff brush and/orvacuumto remove scale
depositsand debris.
1.Weak switch orswitch
out of calibration.
2. Incorrect switch.
1. Replace resettable the rmal switch
2.Verify switch colorcode and approximate
temperature.
Flammable vaporincident 1.Re place water heater.
SERVICE PROCEDURE RG-VIII
Resettable Thermal Switch
Testing and Replacement
The Bradford White
DEFENDER
Safety System®
Color Code
Blue
Approximate switch
activation temperature
(open)
240°
Yellow 270°
Red 290°
Resettable thermal switch
color code reference.
34
34
34