Fault on boiler?

[Luminous]

Just finished a domestic rewire, tested board last week and everything fine . The boiler has now been installed and I went back to connect up to FCU and to put in bonding for gas amongst other things.

The RCD has started tripping when the boiler is switched on. I ran tests again, everything fine. However this is BEFORE I had put in bonding. I even went as far as putting a socket on FCU and put the kettle on! Everything still fine.

Guy comes from boiler place ( I think its a gloworm) and says its not boiler its a fault with the electrics. He suggests to my client that there is an earth fault. I went back again and tested everything again. All ok except now the rcd failed all test including mechanical push test button. Seeing as the only thing I had changed was the bonding I removed it and RCD then worked fine. I turned power back on without bonding no problems. However if I put bonding back in it trips whenever any load is applied. Ive also put boiler on plug and powered it from next door. The boiler doesnt trip next door but doesnt fire up, it tries getting so far as alight, but then powers down again.


Am I missing something. I need to explore all avenues before I tell customer thats its definitely the boiler.

 

[alanl]

Hmm, possible earth leakage fault, and you plug it into next doors supply, and remove the main protective bonding when the installation is live?

Firstly, is this a combi or system boiler?
What type of plan has it if not a combi?

Sounds like a valve has a problem.
Unlikely to be an internal boiler fault.

And please, keep the bonding in-situ, you could be leaving the gas/water pipes live through the house.

 

[Sintra]

Is the bonding you are talking about main or supplementary?

 

[telectrix]

could be a N-E voltage coming from the C/H system. temporarily by-pass the RCD so you can try and measure it.

 

[Luminous]

Sorry guys, just gas bonding removed temporarily after fault arose. House is empty and power has only been on whilst ive been testing.

boiler is a combi.

 

[telectrix]

if the boiler is trying to fire up, then locks out, you have a problem on the heating system. once that's sorted, the RCD problem will probably disappear.

 

[Sintra]

Think about how an RCD works and why it trips. Removing the bonding to get an RCD to hold is just plain dangerous.

 

[Clive P]

Hi,

Just a thought, you haven't lost the Neutral at the Boiler have you?

Regards.

 

[Edd]

boiler can lock out if L-N are reversed, check polarity

 

[Luminous]

Gas bonding was removed whilst I tried to narrow down what was happening. It was put straight back in. Ive not switched power on apart from testing.

 

[Guitarist]

All ok except now the rcd failed all test including mechanical push test button.

If the RCD has failed this test, then it is faulty, or connected incorrectly. The "push-button" test is an internal self-test and nothing to do with the installation (provided that L-N-E are all correct).
Sounds like you have either done something wrong on the CU install, or the supply has a fault.

 

[Sintra]

Just finished a domestic rewire, tested board last week and everything fine . The boiler has now been installed and I went back to connect up to FCU and to put in bonding for gas amongst other things.

The RCD has started tripping when the boiler is switched on. I ran tests again, everything fine. However this is BEFORE I had put in bonding. I even went as far as putting a socket on FCU and put the kettle on! Everything still fine.

Sorry guys, just gas bonding removed temporarily after fault arose. House is empty and power has only been on whilst ive been testing.

boiler is a combi.

Gas bonding was removed whilst I tried to narrow down what was happening. It was put straight back in. Ive not switched power on apart from testing.

From what you are saying the installation was tested before the gas bonding was even installed. Seems a strange way of doing things.

 

[Luminous]

Hmm, suppose so. Just the way it happened. Didnt have as much 10mm on the van as I thought. Assembled ccu in the afternoon and thought might as well test it rather than finish early. Went back at a later date with 10mm.

 

[Sintra]

And have you retested now you have introduced parallel earth paths?

 

[alanl]

Stop digging a hole.

Dont energise a circuit without main protective bonding in place.
And, of course, you will have to do your live tests again, as the MPB will influence the results.

 

[guest119]

Faulty pump? Water and lecy.
Can you disconnect it and megger it?

Boydy

 

[Geordie Spark]

if the boiler is trying to fire up, then locks out, you have a problem on the heating system. once that's sorted, the RCD problem will probably disappear.

Are the isolating valves on both the boiler Flow and Return open??

 

[Luminous]

Yes, Ive said I have energised circuits without gas bondimg in place, simply to perform functional tests.Ill hold my hands up, not good practice.
it really was how things panned out though, honestly.
Ive had to retest the whole caboodle again anyway in light of problem so i may aswell have gone home.Surely only have to do PFC test again though?

 

[Geordie Spark]

From what you are saying the installation was tested before the gas bonding was even installed. Seems a strange way of doing things.

Maybe he's an Irishman. :jester:

 

[sledgehammer]

Instead of help you get criticised about the bonding? Who cares, the house is empty, probably plastic too. How many houses have you seen with no bonding in use for year on year, or relying on the bond on the water for an earth path at all being picked up via next door. Break it down and test it out. That said you should've just gone home.