SERVICE PROCEDURE AG-III
Gas Control Testing and Replacement
For Models using White Rodgers or
Robertshaw Gas Control
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 minutes. 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 gas control.
Alligator clip to copper sheath
Probe top terminal on back of
gas control
of thermocouple
Figure 20
Step 6. With a meter reading of 13 millivolts or greater, rotate knob of gas control 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 gas control should be replaced.
MAGNET ASSEMBLY TESTING (Robertshaw Control)
Step 1. Disconnect thermocouple from gas control.
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.
Figure 21
Figure 22
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 gas control 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 gas control should be replaced.
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