Bradford White 25X78B N Series, Service Manual

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THERMO C OU P LE RE P L AC EMENT
Step 1. Turn off gas supply to water heater. Rotate knob of gas control to “OFF” position.
Step 2. Remove outer jacket door.
Step 3. Slide open inner combustion chamber door.
Step 4. Disconnect thermocouple from gas control. Locate other end of
thermocouple inside of combustion chamber and remove from pilot bracket. Pull firmly pulling away
from the pilot assembly.
Step 5. Install new thermocouple into pilot bracket making certain the thermocouple is fully engaged into the pilot
bracket. Connect other end of thermocouple to gas control (finger tight + ¼ turn).
Step 6. Route carefully through the relief opening in the combustion chamber skirt.
Step 7. To resume operation follow the instructions located on the lighting instruction label or the lighting
instructions located in the installation and operation manual.
Step 8. Slide inner door closed when finished.
S ERVI C E P RO C E D URE A G-I
Thermocoup l e Testin g and Rep l acement
F or M ode l s U sin g White Rod g ers or
Robertshaw Gas Contro l
P a g e 6
F i g ure 3
F or White Rod g ers g as
contro l , depress knob
s l i g ht l y and rotate
c l ockwise to the “O FF ”
position .
F or Robertshaw g as
contro l , rotate knob
c l ockwise to the “O FF ”
position .
Step 1. Disconnect thermocouple from gas control.
Step 2. Using a multimeter capable of measuring millivolts, connect
one alligator clip to the end ball or contact portion of the
thermocouple, and the other alligator clip to copper portion of
the thermocouple.
Step 3. Following the lighting instruction label on the heater, proceed to light the pilot and allow to operate for
three minutes. A reading of 20 to 30 millivolts indicates good thermocouple output.
O P EN C IR C UIT THERMO C OU P LE TE S TING
F i g ure 4
Thermocoup l e position
F i g ure 1
F i g ure 2
NOTE:
I t wi ll be necessary to ho l d the g as contro l
knob down in the “ PI LOT” position
continuous l y throu g hout this test .
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