Bradford White U-100T-88R-3N - Manual (Page 18)

Step 1. Remove outer jacket door.
Step 2. Disconnect red wire leads from resettable thermal switch.
Step 3. Using a multimeter capable of measuring continuity (Ohms),
place one probe of meter on one of the brass connection tabs of
the resettable thermal switch, and the 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. An open switch can be reset by depressing the red colored
button located at the center of the switch. The overheating condition must be determined prior to putting the
water heater back in service.
Resettable Thermal Switch Continuity Testing
PROBABLE CAUSE FOR RESETTABLE THERMAL SWITCH ACTIVATION
PROBABLE CAUSE CORRECTIVE ACTION
Burner Failure
1. Inspect burner per SERVICE PROCEDURE
VI
2. Replace burner per SERVICE PROCEDURE
VI
Weak switch or switch
out of calibration.
1. Replace resettable thermal switch
SERVICE PROCEDURE VII
Resettable Thermal Switch
Testing and Replacement
Red Wire Leads
Page 18
ECO-MAGNUM
75/100-Gallon Atmospheric
18