Resettable Thermal Switch Testing And Replacement - Bradford White RG130T*N Series Service Manual

SERVICE PROCEDURE RG-VIII
Resettable Thermal Switch
Testing and Replacement
RESETTABLE THERMAL SWITCH CONTINUITY TESTING
Step 1. Remove outer jacket door.
Step 2. Disconnect 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 overheating condition. The
switch is designed to open at predetermined temperatures depending on model. 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 heater back in service.
PROBABLE CAUSE FOR RESETTABLE THERMAL SWITCH ACTIVATION
PROBABLE CAUSE
Insufficient combustion air
1. Weak switch or switch
out of calibration.
2. Incorrect switch.
Flammable vapor incident
CORRECTIVE ACTION
1. Verify adequate combustion air supply is
available.
2. Clear jacket slot openings of any dirt, dust,
restrictions or other obstructions.
3. Inspect flame arrestor plate and clean with a
stiff brush, compressed air and/or vacuum
to remove scale deposits and debris.
1. Replace resettable thermal switch.
2. Verify switch color code and approximate
temperature.
1. Replace water heater.
SERVICE PROCEDURE RG-VIII
Resettable Thermal Switch
Testing and Replacement
RESETTABLE THERMAL SWITCH CONTINUIT
Step 1. Remove outer jacket door.
Step 2. Disconnect wire leads from resettable thermal sw
Step 3.
Using a multimeter capable of measuring continu
place one probe of meter on one of the brass con
tabs of the resettable thermal switch, and the rem
probe on the other connection tab.
Step 4. If continuity is indicated, the switch is closed, allow
Step 5. If continuity is not indicated, the switch is open, po
switch is designed to open at predetermined temp
can be reset by depressing the red colored button
overheating condition must be determined prior to
PROBABLE CAUSE FOR RESETTABLE THERMAL SWITCH ACT
Resettable thermal switch
PROBABLE CAUSE
color code reference.
Approximate switch
Color Code activation temperature
Blue
Insufficient combustion air
Yellow
Red
1. Weak switch or switch
out of calibration.
2. Incorrect switch.
Flammable vapor incident
CORRECTIVE ACTION
1. Verify adequate combustion air sup
available.
(open)
240°
2. Clear jacket slot openings of any dir
restrictions or other obstructions.
270°
3. Inspect flame arrestor plate and cle
stiff brush, compressed air and/or
290°
to remove scale deposits and deb
1. Replace resettable thermal switch.
2. Verify switch color code and approx
temperature.
1. Replace water heater.
31
31