Thermal Well Testing - Bradford White TTW 75 SERIES Service Manual

Gas Control Testing
See pages 24 & 25 for gas control
input & output testing.

Thermal Well Testing

Position gas valve power
switch to the "OFF"
position and disconnect
thermal well harness from
gas control.
Using a multi-meter set to
the Ohms setting,
determine the resistance of
thermal well sensors 1 & 2
(see photos 19 & 20)
Once the thermal well resistance values are known, the water
temperature must also be known to determine if the resistance
values are correct. See page 24 to obtain water temperature.
Are thermal well resistance values correct?
Thermal well OK
Disconnect thermal
well wire harness
Using a multi-meter set to the ohms setting, insert one meter probe into center wire
position of thermal well connector, insert the second probe into either of the outside
wire positions (see photo 19).
Alternate the probe on the outside position to the opposite outside wire position
(see photo 20).
N
Y
TTW SERVICE PROCEDURE VI
Gas Control/Thermal Well Testing and
Replacement
19
Replace thermal well
(see page 25)
20
Page 23
23