boiler fault finding

[Steve]

If you are called to a boiler tripping an RCD, what would you look for, and how would you test?

Had BG out today to ours, and they turned it back on and said nothing wrong with it. As soon as I turned it on last night, the RCD tripped.

 

[gassafeman]

Extremely vague Steve.

I would look for an electrical fault and diagnose accordingly. Cant really advise you delving into your boiler.

Turned it on? What does that mean? You put the heating on? You ran a hot tap? You turned the fused spur on?

A bit more info would help.

Paul

 

[mickyg]

depends on what the boiler and system was, but likely suspects are:-
Pump (leaking or motor fooked)
Fan
Gas valve(less common)
Motorised valves with pump valve gland nuts leaking into them(surprisingly common)
back boiler supply cable burned
any leaks which may get to electrics

 

[gassafeman]

mickyg,

Im only making assumptions on the boiler Steve has - a Worcester 9.24 Electronic if I remember his previous posts.

Im surprised its under a BG contract as many people here would give him advice as a regular DIYnot member!

The pump is the first 'port of call' but I'd be Ill advised to tell him to test it, as Im unsure of his electrical experience. Im sure a well placed call by Steve to BG would have this boiler repaired in the next 3 weeks or so

 

[Steve]

Im only making assumptions on the boiler Steve has - a Worcester 9.24 Electronic if I remember his previous posts.

Im surprised its under a BG contract as many people here would give him advice as a regular DIYnot member!

The pump is the first 'port of call' but I'd be Ill advised to tell him to test it, as Im unsure of his electrical experience. Im sure a well placed call by Steve to BG would have this boiler repaired in the next 3 weeks or so

Its not my property, its my parents'. Correct on the boiler though. 18 years old.

When I said "turned it on", i meant the fused spur. The boiler was not under load or hot when i powered it up - the pilot light was burning this is all. I was fault finding - turned everything off and the RCD would hold in. As soon as I flicked the FCU for the boiler on, the RCD tripped again. It was not calling for DHW or CH. The pump was not on.

Anyhow, the boiler was isolated all night, the engineer attended today and turned it on at the mains, and did a full safety check on it, nothing wrong.

I'm not going to test the boiler or anything (why should I, thats what we pay BG to do), I just wondered how it should be done. I was not about when the engineer attended today, but I fully intend to be if they are called out again. And btw, I am pretty handy with electrics.

 

[gassafeman]

Steve,

A full safety check would involve flue performance, burner pressure(s) on CH and HW, integrity of the seals on the boiler, location, & flue and PRV termination.

Was this carried out with no electrical problems occuring?

Paul

EDIT: Steve, I dont doubt your electrical knowledge, ( just looked up some previous posts) but you may invalidate your BG warranty if they think you have.

 

[davebgas]

What boiler is it?? Did someone say an 9.24?

 

[Steve]

What boiler is it?? Did someone say an 9.24?

Yes. Worcestor 9.24 electronic.

Paul, AFAIK, they test flue performance (poke a long tube into the massive flue?), run hot water for a while, whilst looking at the boiler, turn on the heating. And they take off the side panels too sometimes. It was only safety checked in June anyway, but they do it on every visit (says on the work forms).

I am aware of warranties being naffed by DIY.

I guess its one of those things. If BG cant find anything wrong with it and it happens again, I'll run a seperate non RCD circuit for it and the freezer (not a long way and can run it in a box with pipework)

Can pilot lights blow out? If so, and theres no power, does the gas shut off?

 

[mickyg]

pilot light shouldn't generally blow out under normal operation, however it will go out if you turn the power off because it needs the fan for adequate air supply for combustion and dispersal of poc. If it does it as soon as you turn the power on then I might suspect the fan to be the cause as it runs constantly.
If its working at the time of the visit then they should still be checking resistance of any power consuming components, as well as resistance to earth checks etc.. Also if all else fails, I like to give all the wires and harness a "wiggle" whilst its running!

 

[Agile]

I am often called to investigate RCD tripping after others have failed to find the cause.

They dont have the essential tool so thats not surprising !

I use a sensitive clamp on current meter which can measure down to 1 mA.

Tony