HI Spacethgas, yes it does.
Vaillant Combi Compact heating won't shut off!
- Thread starter nickthesafe
- Start date
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it can all get a bit complicated now.
i cant really advise you to do anything further.
i cant really advise you to do anything further.
Thanks Space, I'm not averse to doing things that are complicated - all i need is pointing in the right direction!. The only thing stopping me is not knowing what to look for. It's a bit frustrating as I am a service engineer only in another field. The fault finding section of the manual for the boiler is infuriating since the flow chart always ends up at - "an external part is causing the fault". Since the only extenal part is the CH timer, and that is working fine, it can't possibly be an external part. Are you saying you've got an idea but don't think I should pursue it?, go on..... give us a clue 
id give it a go but i cant really concentrate at the moment as i'm playing poker.
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Sorry maybe if you get a chance tomorrow. Thanks Bud.
maybe if you get a chance tomorrow. Thanks Bud.
have you measured the voltage across the cam switch to see if it falls to zero when it should operate?
Did you locate the o/h stat?
On an earlier model its inside the diecast PCB box and reset from the outside right side of the box towards th back. On another its located just to the right of the diecast box. But I cannot remember where it is on your version. I repair boilers by looking at them and seeing how they work and dont use the manuals except for setting values if not shown on the uinit.
Tony
Did you locate the o/h stat?
On an earlier model its inside the diecast PCB box and reset from the outside right side of the box towards th back. On another its located just to the right of the diecast box. But I cannot remember where it is on your version. I repair boilers by looking at them and seeing how they work and dont use the manuals except for setting values if not shown on the uinit.
Tony
i've got a minute.
the oh reset is black box rubber button.
unscrew pressure differential valve, prise forward.
does pin move when pump runs.
if you press in pin on gv does it light ?
the oh reset is black box rubber button.
unscrew pressure differential valve, prise forward.
does pin move when pump runs.
if you press in pin on gv does it light ?
How is the poker getting on?
I could not play that game because I like to give and share information!
Tony
pokers rubbish. just knocked out. not concentrating.
oh reset is rh side behind pump rh top.
sine 18 works very similar in some respects.
the cam valve & pdif valve both operate through tiny copper connecting tubes.
& yes cam valve operates microswitch. its very important it returns all the way & disengages from microswitch.
oh reset is rh side behind pump rh top.
sine 18 works very similar in some respects.
the cam valve & pdif valve both operate through tiny copper connecting tubes.
& yes cam valve operates microswitch. its very important it returns all the way & disengages from microswitch.
the pressure differential valve operates the pin. concentrate.
but this will not necessarily bring the gas on. the operator head will need energising.
don't even start me on how the burner modulates with the diaphragm pump.
its very interesting.
but im gonna have another go at poker now.
but this will not necessarily bring the gas on. the operator head will need energising.
don't even start me on how the burner modulates with the diaphragm pump.
its very interesting.
but im gonna have another go at poker now.
If its the boiler with a diaphragm pump then thats simple!
It uses a gas valve which has an adition which seems to have been designed to take up the function of an APS. Its actually used that way on an earlier G-W boiler.
It seems to be a design cock-up on this Vaillant model. It still has an APS but to operate the gas valve has a mains operated diaphragm pump very similar to those used to airate a fish tank. This pump only seems to operate that feature on the gas valve. Perhaps I am missing something but the MI dont explain the benefit of using such a complicated system and I cannot see any advantage apart from a lot of bits to go wrong!
That brings another question to the OP. Is there a diaphragm pump behind the diecast box and is it buzzing ?
Tony
we can all pick a potential problem out of the air.
you must approach this in a methodical manner.
what causes the diaphragm pump to fail is generally a badly leaking primary heat exchanger. this generally results in us boiler or loads of labour & a few parts.
you must approach this in a methodical manner.
what causes the diaphragm pump to fail is generally a badly leaking primary heat exchanger. this generally results in us boiler or loads of labour & a few parts.
its got nothing to do with an air pressure switch. it is a means of controlling the burner pressure, it in turn is controlled by the ntc that varies its supply via the boiler flow temp.
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