Boiler tipping RCD question foxing British Gas..and me..ideas please?

[Swags]

Hi, I have a glow work CXI, issue started with the boiler losing pressure each time a cycle ended. was fine on HW only, then when we switch to heating also it started to lose the pressure...

When it came to come back on, pressure was at zero... then it started to trip the RCD, and then it blew the fuse in the PCB.

Engineer has so far, changed PCB, said there was as few leaks inside from seals, now fixed -worked ..then tripped the RCD.

So changed the 3 way switch... worked ok for a few hours... then tripped the RCD...BUT still worked on just Hot Water...

So came back again, decided it was the Flow valve - put in a new one...is working fine....BUT.. as they were here there new boiler guy came round and he tested the electrics by putting a Safe and See (I think it was called, test the earth) in a plug socket in the house, whenever he did this...it tripped the boiler RCD.

Now Boiler is working right now..but I am not confident on for how long, and British Gas have basically washed thier hands of it saying they dont know what it is..

Its a weird and wonderful one I know...but any thoughts on the potential issue please let me know!

All help appreciated i dont think it needs a new boiler as it essentially works!

Thanks



An

 

[Last Plumber]

Is this RCD dedicated to the Boiler?
Or is this RCD covering other things?

 

[Swags]

it has its own circuit breaker, but it trips the RCD related to its bank of circuits. before the PCB, Flow valve, 3 way switch, was replaced it used to also blow its internal fuse - but does not any longer.

Should say boiler is about 9 years old, I have had it for 7 years and been OK. Thanks

 

[snowhead]

and British Gas have basically washed thier hands of it saying they dont know what it is..

Well if B.G with all their expertise and experience can't fix it, then it must be unfixable

I'm surprised they haven't suggested a full rewire and new boiler

Is the boiler holding pressure?
Is this on a BG boiler cover contract?

 

[Swags]

Ah....funnily enough they DID suggest a new boiler...which seems a bit excessive as its mainly working...but with an intermittent gremlin..

It is now holding pressure OK, and no its not on a contract, only issue that remains is the occasional tripping of the RCD.. which I would like to figure out whats causing it before it stops things working again..
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OK so it just tripped again.... worked fine on heating only for hours, then fine with HW also on for a couple more.

Tested it going on and off on timer, when it came back on... was on a few minutes.. then trip..!

 

[Dan1990]

You may have an issue with accumulated leakage. The fault is on another circuit but the boiler is taking it over the limit to trip the RCD.

I’d also have a look at the pump. You may have an issue with the windings or a small water leak which is causing the earth leakage. Next, look at the zone valves.

 

[Swags]

You may have an issue with accumulated leakage. The fault is on another circuit but the boiler is taking it over the limit to trip the RCD.

I’d also have a look at the pump. You may have an issue with the windings or a small water leak which is causing the earth leakage. Next, look at the zone valves.

Thanks Dan, think I will start with the isolation by taking everything else of the circuit and seeing if it still happens. Zone valve is replaced and BG didnt think it was the pump, got to be something though!

 

[Dan1990]

The testing performed by BG was most likely an earth loop impedance test. The tester puts a small current in the earth wire that will not normally trip the RCD, but will do if you already have leakage. A qualified electrician will have appropriate equipment to fault find the problem quite quickly.

 

[Murdoch]

The testing performed by BG was most likely an earth loop impedance test. The tester puts a small current in the earth wire that will not normally trip the RCD, but will do if you already have leakage. A qualified electrician will have appropriate equipment to fault find the problem quite quickly.

I think all BG did was to prove polarity .... which whilst being important, won’t tell you much.

What happens if the rcd is elf switched off?

In my experience, water leaking out of the boiler or 2 or 3 way valves, into the electrics normally makes the RCD trip

 

[Gasmk1]

did they change the whole diverter valve or just the head if just the head this could be one of the problems as they sometimes leak and dependeping on orienttion the small leak trips the electric. Also has anyone checked the RCD isnt faulty

 

[PaulH]

Just check the wiring from the boiler circuit to the fuse box /rcd is balanced ie the positive and negative wires are from the same section in the fuse box