boiler repair

[_shaun_]

posted about this awhile ago. but with it being summer at the time it wasn't a great rush so shall try again.

basically since i got my house the boiler has been playing up.the last occupants turned it off as the house was empty for awhile. and since then its had this issue. it fires up anytime its not been touched for an hour or so. and proceeds to either give me hot water or heating which ever i desire. will run for a few mins i assume till its up to temp and kills the pilot light then once its cold it wont refire.

had a boiler lad out and he said it was the pressure sensor. so he ordered and fitted a new one but didn't work. at this point i didn't really want to pay more call outs and labor along with trying to fit making arrangements to be in the house along side work. so be reasonably competent at most mechanical and electrical things i decided to have a look. i figured as it fires but doesn't relight it was possibly thinking the flame was still there so not firing so ordered a new flame detector. and also a temp sensor to cover that as-well in case it was thinking it was still to temp. fitted both still the same so now am thinking either ignitor's are on there way out and possibly are effected by heat? or expensive option of PCB being faulty. wondering if anyone with a background in boilers fancy's giving there option as i spent all my penny's on car parts and its getting cold outside

a run down of whats happening.

turn tap or heating on and the fan starts.

diverter valve moves if required.

pressure sensor clicks over ( new one fitted and also checked with muiltymeter)

gas valve not sure on this i cant hear anything from it when it fires and when it doesn't fire so i can only assume its working.

if not been touched fires up no bother.

runs for random amount of time and cuts burner.

fan still running

pressure switch still showing its working

nothing happening?

its a ideal mini c24 boiler with a manual here http://idealboilers.com/installer/wp-content/uploads/sites/2/2013/08/mini_is32.pdf

prob a bit long winded thread but i don't want to waste money on the ignitor's if its the pcb and vice versa and i really don't want to waste money on these if its something am just totally overlooking but the whole boiler system looks straight forward.

any help be great

cheers shaun