central heating tripping r.c.d.

dingodeano · 27 Sep 2007

hello guys great forum. ( my first post )
I am a electrician ( hope im ok on this territory

)my mate has asked me to go round, because when he turns on his CH via the clock this causes his R.C.D. to trip out. ( this has developed because at first it was fused spur which kept blowing fuse )
I will go round and check out his wiring to and from timer to accessories, However my knowledge of heating wiring circuits is not brilliant.
What accessories usually give such a fault?
Apart from a visual of connections and disconnecting each item as process of eliminiation i wouldnt know if a valve or pump was faulty.
From what i can gather there is a
pump.
valve.
boiler.
and i suppose the timer itself.
can any of you give me pointer or two?

P.S. its an old style system thats all i know as of yet.

EliteHeat · 27 Sep 2007

Well if it only happens on CH then it is odds on that it will be the motorised valve.

dingodeano · 27 Sep 2007

THX. I will make valve my first call in my process of elimination providing there are no obvious wiring faults.
by the way the valve is the little square thing ,galvanised cover with a lever on? oh and the valve just has a Live, Neutral, and Earth feed?

JohnD · 27 Sep 2007

it's usually the watery things - pump leaking onto connections or into motor, drip inside boiler casing onto PCB. the 3-way valve (depending how it's fitted) usually has the electric head above the pipes and valve, so less prone to leaks.

Some old systems have gravity feed to boiler, so no 3-way valve

Could also be a chafed or trapped wire, especially if it's been recently serviced.

I don't know much about boilers, they have a removable cover, but some are pressurised inside. If you know the make and model someone here will know if you can safely open it.

dingodeano · 27 Sep 2007

Thx again if it is a wiring problem i will find it !! However my knowledge of heating controls and accessories is not that great so any help with comon faults or suggestions are greatly appreciated thx lads.

nickso · 27 Sep 2007

very common faults for blowing a fuse on that system would be the pump electrics filling with water or as elite said the valve could be faulty. the spindles can leak onto the electrics inside the valve causing shorts.

isolate the pump first as its an easy hit. sometimes you will open the pump elecs and it will be obvious its the fault either by the water pouring out or the smell of burny things.

Andyboogie · 15 Apr 2016

beware! If it helps.....
15 Apr 2016
By andysceptic
Berkshire
" For a couole of months the RCD intermittently would trip. Got so frequent that RCD would trip instantly one circuit was activated, then only when central heating turned on. Identified culprit - the new Grundfos pump fitted in February. Purchased as a replacement for a similar model, same make, that had been reliable for some 23 years. So it was one of the last components to be checked - very time consuming especially as the tripping was so intermittent - arn't these the worst type of problems to identity!?
However, based on the fact that the old pump was so reliable, and after maintenance went back in to replace the new one (it was Sunday afternoon, no replacement available at local Screwfix) - everything working fine ever since, so I have given a good review.
Just something I thought I'd alert fellow folk to, a rogue new pump that you wouldn't expect.
Screwfix staff (Woodley) couldn't have been more helpful, had ordered a replacement then refunded when I found that I didn't need it. "

Agile · 15 Apr 2016

Bit late for warning them.

That discussion was NINE years ago.

Andyboogie · 16 Apr 2016

Yeah but..... When one Googles a problem you will find that the 'hits' have no respect for age!
Thus this is for anyone currently seeking answers.
I would guess that the original guys have fixed their problem - or invested in hot water bottles

jeff the gasman · 17 Apr 2016

I bet it's been mended by now.

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central heating tripping r.c.d.

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