Bradford White U-65T-55FR-3N - Manual (Page 14)

Thermal Well Testing
Thermal well testing
Position gas control knob to the
“OFF” position and disconnect
thermal well harness from gas
control.
N
Y
Using a multi-meter set to the ohms setting, insert one meter probe (see caution)
into center wire position of thermal well connector, insert the second probe (see
caution) into either of the outside wire positions (see photo 1).
Alternate the probe on the outside position to the opposite outside wire position
(see photo 2).
Replace thermal well
(see page 16)
Using a multi-meter set to the
Ohms setting, determine the
resistance of thermal well sensor
(see caution photos 1 & 2)
Disconnect thermal
well wire harness
1 2
Replace gas control
(see page 16)
SERVICE PROCEDURE ED-V
Gas Control Replacement Thermal
Well and Chamber Door Sensor
Testing and Replacement
Page 14
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 15 to obtain water temperature.
Are thermal well resistance values correct?
CAUTION
DO NOT use standard multimeter probes for this test.
Doing so will damage connector. Use special pin type
electronic probes or small diameter wire pins inserted
into connector.
If Control has gone into lockout due to excessive
tank temperature (four flash, 3 second pause) reset
control by rotating gas control knob to “OFF”
position. Then follow lighting instructions and return
gas control knob to desired setpoint.
Observe heater operation. If control
continues to lockout due to
excessive tank temperature,
proceed to thermal well testing to
determine cause.
14