Thermopile Testing And Replacement - Bradford White UDH Series Service Manual

Uds / udh series ultra low nox direct vent water heaters
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The Bradford White
OPEN CIRCUIT THERMOPILE TESTING
The following test should be performed while the pilot flame is on.
Step 1.
Turn knob to pilot position and depress.
Step 2.
Continue pressing knob and remove red (+) thermopile wire from the red wire leading from the gas control.
Also remove white (-) thermopile wire from the gas control.
Step 3.
Using a multimeter capable of measuring millivolts, connect the positive side of the multimeter to the
red (+) thermopile wire connector. Connect the negative side of the multimeter to the white thermopile
connector.
Red (+) thermopile wire
Red gas control wire
White (-) thermopile wire
Normal thermopile operation will be between 350mV - 850mV. If reading is less than 350mV, replacement of pilot
assembly is recommended following SERVICE PROCEDURE III.
Step 4.
If thermopile reading is between 350mV - 850mV, remove multimeter and reconnect red (+) thermopile wire
to red wire leading from the gas control. Reconnect white (-) thermopile wire negative (-) terminal on gas
control.
Step 5.
Release Gas Control knob and turn to desired setting to resume normal operation.
SERVICE PROCEDURE II

Thermopile Testing and Replacement

9
White (-) thermopile wire
Red (+) thermopile wire
9

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