SERVICE PROCEDURE AG-III
Combination Thermostat/Gas Valve
Testing and Replacement
COMBINATION THERMOSTAT/GAS VALVE REPLACEMENT
Step 1. Rotate knob of the combina tion thermostat/gas valve
to the “OFF” position.
Step 2. Turn off gas supply towater heater.
Step 3. Disconnect gas supply line from
combination thermostat/gasva lve.
Step 4. Turn off water supply and drain water heater completely.
Step 5. Removeo uter jacket burner access door.
Step 6. Slide openinner combustion chamber door.
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For White Rodgers Control ,
depress knob slightly and r otate
clockwise tothe “OFF” position.
For Robertshaw Control, rotate
knob clockwise to the “OFF”
position.
Step 1. Disconnect thermocouplefr om 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 mag net opening. Do not allow
the probe to make contact with the threaded sides of the opening.
Step 3. If continuity is indic ated, the ECO is OK. If con tinuity is not indicated, the ECO has opened and the
combination thermostat/gasvalv em ust be replaced.
ECO (Energy Cut Off) TESTING
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