andrews Fastflo WHC56 Service Manual page 31

10. Flame rod error.
11. Drain trap water level electrode error.
If error display 12 or 72 appears, then check the
flame rod.
(1) Measure the frequency between the flame rod
and burner case (GUD) when the remote
controller is turned on.
10kHz - 100kHz
Normal
Yes Continue to (2).
No Replace the circuit board.
(2) Measure the current between flame rod (or Blue
1 of connector 78) and electrode.
DC 1µA or higher (during flame
Normal
detection)
Check for connection failure between
circuit board ground and metallic
section of unit, then check the gas
Yes
pressure and airflow (has the flame
been blown out by excessive airflow?).
Replace the flame rod.
No
If error display 29 appears,then check the drain trap
water level electrode.
(1) Measure the voltage between Blue 29 and
Green 32 of connector 38 on the circuit board.
DC 4V or more
Normal
Yes Continue to (2).
• Check the clogging of drain piping,
No
drain trap and connection hose.
• Replace the circuit board.
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