worcester 28 si mk2


hav it

hi i went to a call today at work, with a lock out fault on a 28 si. When i got there i reset it it ran for a few mins then locked it out agian. I opened the cover and could hear the air pressure switch clicking intermitantly, so possbly shorting out.

When i reset the boiler i have power to the air pressure switch. When i create a demand fan starts to run for a few seconds, then cuts out with no power going to fan, pump runs ok and still power to pressure switch. only way to get it to reset is to blow down pressues switch then power goes to fan and it runs for a few mins and cuts out. just thinking if anyone had any dealing with them as all signs say pressure switch.
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Check the fan venturis are clean and there are no blockages/cracks in the aps tubes. Does it work better if the case is off? If so sounds like venturis.
hi no gas4you it only works if i blow down the pressure switch. Then power goes to the fan it works, then starts to cut out after a short while.
I have checked fan its working ok. i have replaced air pipes to fan and cleaned out venturis.. thanks
Has the flue exhaust pipe become detached/out of place or slightly blocked so that boiler is 'breathing in' its own fumes and cutting its self out. (wild stab in the dark :oops: )

It seems you are proving that the aps is ok and if I understand you correctly that it is something else other than the aps that is cutting out the boiler :confused: :?:
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You have not stated clearly what happens when you activate the APS manually.

Does the boiler run normally and keep running?

Have you measured the NO and NC contact resistances on the APS ?


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