vaillant combis - hw call boiler fires; ch call nothing.

chess · 31 Oct 2007

I am a boiler breakdown apprentice, more of an installer, and wonder if somebody could give advice on the "hw call boiler fires, ch call nothing" problem on Vaillant combis.

I haven't been to see the boiler yet but assume the system pressure might be too low on the heating side. Any other ideas???

I ask because there's never the boiler guide with appliances.

gas4you · 31 Oct 2007

It would help if you told us the exact model of Vaillant

chess · 31 Oct 2007

haven't been over yet. customer was unable to tell me. I reckon it may be a Vaillant TurboMax.

Just looking for an idea. If you're unable to speculate on my limited info I will get back to you on that.

gas4you · 31 Oct 2007

You need to start with checking that there is actually an external call for heat and there is 230V present at the switched live.

Until you prove this lifes a total guess

chess · 31 Oct 2007

thanks, i will. till next time

Agile · 31 Oct 2007

If you are an apprentice then surely you are working under the guidance of an experienced engineer?

Tony

chess · 31 Oct 2007

ps i will make sure the roomstat is up, the heating temp control is up and then that there is 230v power to swithced live. this be from the main cable wiring at the boiler? Electrics not my bag.

chess · 31 Oct 2007

AgileTony,

Not necessarily. But I'm after help nevertheless, Installing is my bag. Gaining exp doing breakdowns working for myself. CORGI registered too.

bengasman · 1 Nov 2007

First check for heating failure, like tony said. As far as I know it is the same trick for every vaillant combi you find. Check for 230 between 3 and 5. If there is, check for 230 between 4 and 5.
Just had a great one on an old combi compact. Weak pump would move the hydraulics, and press the micro switch but not quite enough to actually make the contact every time.
Am I correct saying that #3 is SL, 4 IS RL and 5 is neutral? Never seen any documentation that actually tells you which terminal is what.

ChrisR · 1 Nov 2007

chess said:
Electrics not my bag.

It will have to be if you want to do much repairing. Plenty of introductory books about, suggest you get one!

chess · 2 Nov 2007

Which guide do you recommend? I've found John Reginald's 'combination boilers: fault finding and repair'. Do you think this would be a worthy buy?

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vaillant combis - hw call boiler fires; ch call nothing.

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