User Guide

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 over heating 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.

RESETTABLE THERMAL SWITCH CONTINUITY TESTING

PROBABLE CAUSE FOR RESETTABLE THERMAL SWITCH ACTIVATION

PROBABLE CAUSE CORRECTIVE ACTION

Insufficient combustion air

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. Weak switch or switch

out of calibration.

2. Incorrect switch.

1. Replace resettable thermal switch.

2. Verify switch color code and approximate

temperature.

Flammable vapor incident 1. Replace water heater.

SERVICE PROCEDURE RG-VIII

Resettable Thermal Switch

Testing and Replacement

Color Code

Blue

Approximate switch

activation temperature

(open)

240°

Yellow 270°

Red 290°

Resettable thermal switch

color code reference.