L.B. White Pilot - Manual (Page 51)

Testing PProcedures:
(Applies to all thermocouples and gas control valves.)
A. INITIAL PPREPARATION
1. Disconnect the heater from its electrical supply.
2. Close the fuel supply valves to the inlet of the heater.
B. TEST K KIT IINSTALLATION
1. Remove the thermocouple contact from the control
valve.
2. Thread the contact nut of the tester into the control
valve and tighten finger tight plus 1/4 turn.
3. Thread the heater’s thermocouple into the tester and
tighten finger tight plus 1/4 turn.
4. Open the fuel supply valves to the heater.
C. THERMOCOUPLE C CHECK
1. Light the pilot.
2. Set your voltage tester to the DC scale, and if the tester
is so equipped, set the scale to MV (millivolts). Connect
the probes of multimeter to the millivolt tester.
3. Observe the DC voltage reading. The reading should
rise to at least 10 millivolts DC before leveling off. If the
reading never reaches 10 millivolts, discontinue the
test at this point and replace the thermocouple. Start
the test over. If the reading is 10 millivolts or greater,
and the pilot stays lit, discontinue the test and remove
the test kit. Reinstall the thermocouple.
4. Reconnect the heater to its electrical supply.
D. POWER U UNIT C CHECK
1. Close the fuel supply valve to the heater and allow the
pilot flame to be extinguished.
2. Monitor your meter reading. The millivolt reading will
drop slowly as the thermocouple cools.
3. Listen for the “snap” as the power unit within the
control valve drops out (releases) normally within 30 -
60 seconds after pilot flame is extinguished.
4. If the millivolt reading is 4 millivolts DC or greater when
the valve drops out, the power unit within the control
valve is weak. The control valve must be replaced in its
entirety.
Thermocouple and Power Unit Tests
Component
Testing
August 1999
6.3-2 2
Heater Thermocouple
to Tester
Tester
Thermocouple
Contact