hi chaps. slowly getting into fault finding but i am baffled at something. if t a combi fires up ok then shuts off the fires up again etc etc where on earth do you start fault finding? if the boiler stopped at sparking then you would look at ignition/ and ignition proving. i just dont know where to start with these on-ff-on problerms ?? for example ive noticed on the some posting here that a boiler was on-ff-on etc and the aps has been diaognosed but surely the aps itself wouldnt switch on-off-on (unless flue blocked)?? puzzled!!
on-ff-on problems
- Thread starter polpumber
- Start date
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depends on the combi, but rather than a blocked flue it can be a little carp in the venturi which sucks you APS open.
Other faults are faulty thermistors that give incorrect flow temp readings to the PCB, check with a multi meter once hot to see what resistances you get, or plug a new one in and leave out the pocket.
Blocked domestic HE can make boiler overoverheat very quickly, check with a thermometer on the flow/return pipe from main heat exchager.
Or finally could be a sluggish pump not circulating fast enough causing over heat. thats a tough one to check tho!
Happy hunting.
Other faults are faulty thermistors that give incorrect flow temp readings to the PCB, check with a multi meter once hot to see what resistances you get, or plug a new one in and leave out the pocket.
Blocked domestic HE can make boiler overoverheat very quickly, check with a thermometer on the flow/return pipe from main heat exchager.
Or finally could be a sluggish pump not circulating fast enough causing over heat. thats a tough one to check tho!
Happy hunting.
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