Bradford White ECOSTOR2 SDW2504T Service Manual Supplement page 8

EcoStor2™ Solar
If the control has gone into lockout due to
excessive tank temperature (four flash, 3
second pause) reset the control by rotating
the gas control knob to "OFF" position. Then
follow the lighting instructions and return the
gas control knob to the desired setpoint.
Observe the water heater operation. If
the gas control continues to lockout due
to excessive tank temperature, proceed
to thermal sensor and harness testing to
determine the cause.
THERMAL SENSOR AND
HARNESS TESTING
Position the gas control knob to the
"OFF" position and disconnect the
thermal sensor harness from the gas
control.
Using a multi-meter set to the
Ohms setting,
resistance of thermal sensor .
(see caution photos at right)
Once the thermal sensor resistance values are
known, the water temperature must also be known
to determine if the resistance values are correct.
See page 9 to obtain water temperature.
Are thermal sensor and harness
resistance values correct?
Replace gas
control
8
8
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.
Using a multi-meter set to the ohms setting, insert one meter probe (see
determine the
caution) into center wire position of thermal well connector, insert the second
probe (see caution) into either of the outside wire positions (see photo on left).
Alternate the probe on the outside position to the opposite outside wire position
(see photo on right).
Y
ST-II Temperature Sensor
and Harness Testing
Disconnect thermal
well wire harness
CAUTION
N
Repeat Ohm measurement at the
Are thermal sensor resistance
N
Replace sensor
wire harness
sensor connector.
values correct?
Replace thermal
well sensor
Y