Combi Boiler tripping RCD

[North]

Yesterday the RCD tripped when I turned the heating on. It never happen before so I checked inside the combi boiler ( a Glow worm Energy saver 40 )to make sure it did not have any leaks and then I checked the pump in the loft but everything looks OK. I can switch the boiler on if the dial is set to minimum and the RCD wont trip but when I turn the dial slightly, which is what makes the pump run, then this makes the RCD trip. This happen in both cases when switching the central heating or when switching the hot water.
My questions are as follows:
a) Any suggestions on what can cause the tripping?
b)if I can’t find the solution to the problem who should I call first, plumber, electrician or boiler company? I would like to avoid having to call the wrong person for the job!

 

[EFLImpudence]

RCDs trip as a safety precaution because of current leakage to earth - any earth path including you.
It could be an accumulation of small leaks from various parts but if it does it every time the pump starts that would be the likely cause.

The most likely causes are moisture and heating or motor parts.

As you 'seem' to have narrowed it down to the pump, I would suspect that.

You will need an electrician if you really want to find the cause or a plumber to replace the pump and see if it cures the problem

 

[ianmcd]

Firstly a Glow worm energy saver 40 is not a combi boiler, it is easy to find out if it is the pump and any heating engineer should be able to rectify this for you

 

[RickMoore]

You will need an electrician if you really want to find the cause or a plumber to replace the pump and see if it cures the problem

Cheeky ***

Alternatively you could use a heating engineer that can diagnose AND repair the fault.

Electricians are all well and good, but give them something more complicated than a basic S or Y plan and watch their head explode.

 

[EFLImpudence]

It's not a question of S or Y plan.

The OP has a device or devices which are causing current leakage to earth.

This could be 20mA from, say, a fridge and 5mA from the pump.
Whilst replacing the pump will stop the RCD tripping it may not be necessary and will not be an actual cure.

This may be due to the appliance or a wiring fault

Without the electrical test equipment this cannot be determined.

 

[GavThePlumber]

That is so true Rick, i am of the opinion that no electrician should go any where near boilers (or wiring centers for that matter), leave it for people who are qualified to do the job, they shouldn't even remove the case as they do not know if it is decorative or integral casing in 99% of cases

 

[RickMoore]

Without the electrical test equipment this cannot be determined.

Which a good heating engineer will carry and know how to use so your point is ?

 

[EFLImpudence]

If you have an insulation resistance meter and earth leakage current clamp meter then I'm impressed.

 

[EFLImpudence]

i am of the opinion that no electrician should go any where near boilers (or wiring centers for that matter),

If you mean people who aren't really electricians then fair enough but to say that electricians should not go near wiring is ridiculous.

 

[GavThePlumber]

If you mean people who aren't really electricians then fair enough but to say that electricians should not go near wiring is ridiculous.

It is illegal for you to be taking integral casings of boilers and wiring centers are for heating engineers who know what they are doing, not domestic sparks who 99% of the time do not know what they are touching.

 

[EFLImpudence]

wiring centers are for heating engineers who know what they are doing, not domestic sparks who 99% of the time do not know what they are touching.

I must be the 1% then.

Oh. I forgot about an RCD tester - perhaps it is faulty.
How will you know?

 

[RickMoore]

If you have an insulation resistance meter and earth leakage current clamp meter then I'm impressed.

Fluke 1651, Thanks.

That's why I said to diagnose the fault AND replace the pump IF NEEDED. Not change it and see if that stops the problem as you suggest anyone but an electrician would do.

 

[EFLImpudence]

Fair enough.

I've never met a heating engineer then. Perhaps the equivalent 99%.


Earth leakage clamp?

 

[RickMoore]

I borrow my mates on the odd occasion I need one.

I think it's fair to say that being generic about trades abilities can be somewhat unfair at times.

 

[EFLImpudence]