SERVICE PROCEDURE
Combination Thermostat/Gas Valve Testing
and Replacement
ECO (Energy Cut Off) TESTING
Step 1. Disconnect thermocouple from combination thermostat/gas valve.
Step 2. Using a multimeter capable of measuring Ohms (or continuity), attach one lead (alligator clip) to the pilot tube. Insert the other lead (probe) fully into the magnet opening, Be sure the probe makes contact only at the top center of the magnet opening. Do not allow the probe to make contact with the threaded sides of the opening.
Step 3. If continuity is indicated, the ECO is OK. If continuity is not indicated, the ECO has opened and the combination thermostat/gas valve must be replaced.
COMBINATION THERMOSTAT/GAS VALVE REPLACEMENT
Step 1. Rotate knob of the combination thermostat/gas valve to the “OFF” position.
Step 2. Turn off gas supply to water heater.
For White Rodgers Control, depress knob slightly and rotate clockwise to the “OFF” position.
Step 3. Disconnect gas supply line from combination thermostat/gas valve.
Step 4. Turn off water supply and drain water heater completely.
Step 5. Remove outer jacket burner access door.
Step 6. Right side inner door removal.
For Robertshaw Control, rotate knob clockwise to the “OFF” position.
a)Disconnect resettable thermal switch wire leads (leading from combination thermostat/gas valve) and remove wire tie from feedline.
b)Remove (2) 1/4" hex drive screws from right side inner door.
c)Remove (2) 1/4" drive screws from flange section of inner door.
d)Remove right side inner door and set aside. Be careful not to damage gasket material on inner door.
Remove | Resettable Thermal Switch |
Wire Tie | Wire Connection |
¼" Hex Drive Screws shown on 
Right Side Inner Door.
¼" Hex Drive Screws at
Flange section of Inner Door
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