SERVICE PROCEDURE
Combination Thermostat/Gas Valve Testing
and Replacement
THERMOCOUPLE TESTING
See SERVICE PROCEDURE
MAGNET ASSEMBLY TESTING (White Rodgers Control)
Step 1. Following the lighting instruction label on the heater, proceed to light the pilot and allow to operate for
three minuets. If the pilot will not stay lit, hold the pilot button (located on the combination thermostat/gas valve) down during this test
Step 2. Using a multimeter capable of measuring millivolts, connect one lead
using an alligator clip to the copper sheath of the thermocouple, use the second lead of the multi meter to probe the top terminal located at the back of the combination thermostat/gas valve.
Probe top terminal on back of combination
thermostat/gas valve
Alligator clip to copper sheath of thermocouple
Step 6. With a meter reading of 13 millivolts or greater, rotate knob of combination thermostat/gas valve to the “OFF” position.
Step 7. The magnet should remain closed for a drop of at least 6 millivolts. You will here a “snap” or “click” sound
when the magnet opens, if you hear this sound prior to a drop of 6 millivolts, the magnet is out of specification and the combination thermostat/gas valve should be replaced.
MAGNET ASSEMBLY TESTING (Robertshaw Control)
Step 1. Disconnect thermocouple from combination thermostat/gas valve.
Step 2. Connect a thermocouple adaptor
(BWC P/N
Step 3. Reconnect thermocouple to adaptor. Make certain all connections are tight (finger tight plus ¼ turn).
Step 4 Using a multimeter capable of measuring millivolts, connect one alligator clip to the set screw of the adaptor and the other alligator clip to copper portion of the thermocouple.
Step 5. Following the lighting instruction label on the heater, proceed to light the pilot and allow to operate for three minuets.
Step 6. With a meter reading of 13 millivolts or greater, rotate knob of combination thermostat/gas valve to the “OFF” position.
Step 7. The magnet should remain closed for a drop of at least 6 millivolts. You will here a “snap” or “click” sound
when the magnet opens, if you hear this sound prior to a drop of 6 millivolts, the magnet is out of specification and the combination thermostat/gas valve should be replaced.
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