Smeg CW521D Manual page 24

Err23 Boiler does not heat up as expected
Err24 Boiler temperature probe malfunction
Err25 Boiler water filling malfunction
Err26 Boiler emptying malfunction
Boiler emptying malfunction – with
Err27
tank full
Boiler heating
Err28
(overheating)
‐ CW 521/531
The problem might occur because water is
continually entering the tank (the causes are as for
Err5 – see above)
If it persists, check in this order:
‐ damaged boiler heating element
‐ contactor failure,
‐ boiler safety thermostat failure,
‐ boiler temperature probe faulty or incorrectly
positioned
‐ motherboard relay failure,
Important: if the boiler heating element is damaged,
this might be due to operation with no water in the
boiler ‐ the pressure switch is indicating full even with
the boiler empty: check and if necessary replace the
boiler air trap and/or the relative pressure switch:
the problem is generally preceded by "boiler
overheating E28"
boiler temperature probe disconnected or not
working
The boiler does not fill within the allowed time: check
water intake tap, dynamic pressure in intake system,
cleaning of water intake filter, possible damage to
water intake hose
Or check in this order:
‐ boiler pressure switch has failed (continuous empty
reading)
‐ pipe leaking/disconnected (water entering pipe)
‐ check that rinsing spray arm nozzles are clean
‐ boiler pressure switch has failed (continuous full
reading)
‐ pipe leaking/disconnected (water entering pipe)
‐ rinsing pump not working
Boiler pressure switch has failed (continuous full
reading)
First check:
‐ boiler pressure switch has failed (continuous full
reading)
‐ pipe leaking/disconnected: water entering pipe
malfunction connected to air trap, pressure switch continues to
give full reading even with boiler empty, heating
element operating dry
Or:
‐ circuit board relay failure, or
‐ contactor failure
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