Bradford White UCG100H199 Installation & Operation Manual page 43

Definition
Error Code
of Code
High Limit
80 (Overheat
Condition)
DHW
93 Sensor
Fault
Flame
detected
105
out of
sequence
Ignition
110 Failure
Occurred.
Light-off
Rate
122
Proving
Failed
Cause of Problem and Actions Taken to Correct
• Check the wiring from the sensor to the control module.
• Measure the resistance of each outside wire to the center wire.
• If either outside wire has a much different resistance reading, replace the sensor.
• Make sure the sensor is securely held inside the well with the clip.
• If the problem persists and the sensor and wiring check O.K., then replace the
control module.
• Check the sensor wire harness from the sensor to the control module.
• Make sure there are no loose connections to the control plug.
• Check the resistance reading from each of the outside wires to the center
(common) wire.
• If the ohm readings are not fairly close, replace the sensor.
• Replace the control module if the problem persists and the sensor and wire
connections are not defective.
• Check to see if flame is present inside the combustion chamber before or after the
ignition cycle.
• If so, check to make sure the gas valve is wired correctly.
• Check for voltage at the gas valve connection.
• Replace the gas valve if defective.
• If no flame is visible outside of the ignition sequence/run cycle, then make sure the
flame sensor is wired to the correct terminal.
• Make sure the ignition cable is not crossing the flame sensor wire or ignition
ground wires.
• If problem persists and all other checks have been verified, replace the control
module.
• Burner failed to light or stay lit after 3 retries.
• Hold condition – will reattempt ignition after 15 minute waiting period.
• Check gas valve wiring and gas valve operation during the ignition cycle.
• If burner lights but quickly goes out, check the flame sensor wire or the flame
sensor.
• If the flame sensor rod is badly corroded with deposits, clean with sandpaper or
replace.
• Check the inlet gas supply to make sure the pressure is sufficient and does not
drop after the gas valve opens.
• Make sure the combustion blower is operating during the ignition and run cycle.
• Check the venting system to make sure the inlet and exhaust terminals and
venting system is not blocked.
• If blower speed is not verified from the PWM (Pulse Width Modulation) signal
within 5 minutes, the previously described error code "62" changes from a hold
condition to this lockout code condition.
• Check the harness and pin terminals for a good connection to the control module.
• Replace the blower or control module if the wire harness is good.
43
LOG?
YES
NO
YES
NO
YES