Step 1. Closed circuit testing is the preferred method for testingthermocouple. Followingthe lighting instruction
label on the heater, proceed to light the pilot and allowto operate for three minuets. If the pilot will notstay
lit, hold the pilot button (located on the combination thermostat/gas valve) down during this test
Step 2. Using a multim eter capable of measur ing millivolts, connec t 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 lo cated at the back of the c ombination thermostat/ gas valve.
Step 3. If meter reads 10 mil livolts or higher, the thermocou ple is OK. If reading is below 10 mi llivolts,
replace the thermocouple.
CLOSED CIRCUIT THERMOCOUPLE TESTING (White Rodgers Control)
The Bradford White
DEFENDER
Safety System®
Probe top terminal on
back of combination
thermostat/gas valve Alligator clip to copper
sheath of thermocouple
Step 1. Disconnect thermocouple from combination thermostat/gas valve.
Step 2. Connect a thermocouple adaptor
(BWC P/N 239-44642-00, Robertshaw P/N 75036) at the
thermocouple location in the combination thermostat/gas valve.
Step 3. Reconnect thermocouple to adaptor. Make certain all
connections are tight (finger tight plus ¼ turn)
Step 4 Using a multimeter capable o f measuring millivolts, c onnect
one alligator clip to the s et 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. If the pilot will no t stay lit, hold the red reset butt on (located on the combination
thermostat/gas valve) down duringthis test
Step 6. If meter reads 13 mil livolts or higher, the thermocou ple is OK. If reading is below 13 mi llivolts
replace the thermocouple.
CLOSED CIRCUIT THERMOCOUPLE TESTING (Robertshaw Control)
SERVICE PROCEDURE RG-II
Thermocouple/Thermopile Testing and
Replacement
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10
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