Bradford White EF120T4003N3, Руководство по обслуживанию

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18
Troubleshooting
80
High limit
(overheat
condition)
x Check the wiring from the sensor to the control board.
x Measure the resistance of each outside wire to the center wire (resistance chart found on
pg 21).
x If either outside wire has a much different resistance reading, replace the sensor.
x Make sure the sensor is securely held inside the well with the clip.
x If the problem persists and the sensor and wiring check O.K., then replace the control
board.
93
DHW/Temp
sensor fault
x Check the sensor wire harness from the sensor to the control board.
x Make sure there are no loose connections to the control board.
x Check the resistance reading from each of the outside wires to the center (common) wire
(resistance chart on pg 21).
x If the ohm readings are not within 5°F, replace the sensor.
x Replace the control board if the problem persists and the sensor and wire connections are
not defective.
105
Flame
detected
out of
sequence
x Check to see if flame is present inside the combustion chamber before or after the ignition
cycle.
x If so, check to make sure the gas valve is wired correctly.
x Check for voltage at the gas valve connection.
x Replace the gas valve if defective.
x If no flame is visible outside of the ignition sequence/run cycle, then make sure the flame
sensor is wired to the correct terminal.
x Make sure the ignition cable is not crossing the flame sensor wire or ignition ground wires,
and that there is no moisture on the flame sensor.
x If problem persists and all other checks have been verified, replace the control board.
110
Ignition
failure
occurred
x Burner failed to light or stay lit after 3 retries.
x Hold condition – will reattempt ignition after 15 minute waiting period.
x Check gas valve wiring and gas valve operation during the ignition cycle.
x If burner lights but quickly goes out, check the flame sensor wire or the flame sensor.
x If the flame sensor rod is badly corroded with deposits, clean with sandpaper or replace.
x Check the inlet gas supply to make sure the pressure is sufficient and does not drop after
the gas valve opens.
x Make sure the combustion blower is operating during the ignition and run cycle.
x Check the venting system to make sure the inlet and exhaust terminals and venting
system is not blocked.
122
Light-off
rate proving
failed
x 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.
x Check the harness and pin terminals for a good connection to the control board.
x Replace the blower or control board if the wire harness is good.
123
Purge rate
proving
failed
x Check wiring and correct any potential wiring errors.
x Check VFD’s (variable-speed fan drive) ability to change speeds.
x Change the VFD.
x If the fault persists, replace the module.
137
ILK open
(interlock
open)
x Check if blocked vent pressure switches or vent limit switch are open.
x
If all switches check O.K., replace control board.
18