Fault with Worcester 28i tripping consumer unit

[the1bandit]

Hi,

My boiler has failed (Worcester 28i). It trips the RCD as soon as I attempt to turn on the central heating. But, when I turn on hot water it lets me have water fine until I turn off the tap and after the fan/pump run for about 5 seconds it trips the consumer unit again.

My friend who installed the combi has replaced the pump, fan, various things (apart from gas valve) and even the board (made it worse).

Does anyone have any ideas?

Any help appreciated!

Paul Morris

 

[bazdaman]

I would of guessed pump, hes costing you a fortune if hes changed all them parts with no joy, what fuse is in the spur/plug

 

[the1bandit]

thanks for the response baz.

He has a spare 28i and is a good friend. everything he has replaced he is ok with and wont charge me because it hasn't fixed it. They are not new parts so they could also be faulty but he says its doubtful.

Anyway to know definitely its the pump? I have asked him about the pump several times and he says he has eliminated it...

3 AMP fuse in the plug - no spur. This was replaced too at the start of today.

Paul

 

[picasso]

Check your external controls.

 

[the1bandit]

Thanks Picasso. From day one the mechanical timer was disconnected. We had an electronic one fitted. We have even disabled it and it still doesn't work. Weird problem...

 

[picasso]

Did your mate change the transformer ?

 

[ianmcd]

+1 for Transformer you can usually tell by removing it and physically inspecting it for cracks or swelling and sometimes they just smell acrid

 

[the1bandit]

Thanks both. I will suggest that the transformer be changed.

 

[the1bandit]

Thanks both. I will suggest that the transformer be changed.

 

[the1bandit]

Hi all,

Another day and still the same problem. The old transformer was replaced with a spare. Same fault. Old one and replacement dont have a bad smell etc...

Engineer says all sensors have been bypassed/eliminated but it is still the same.

As soon as you turn the CH dial the RCB trips. Hot water ok until you switch it off and after exactly 5 seconds it will trip.

Does anyone know what happens at this 5 second mark that we could check?

Thanks again

Paul

 

[picasso]

The pump does not run for hot water on this model, when you turn off the tap a relay on the board brings the pump on for pump overrun or central heating if its being called for, dont know if there is a five second delay but I would be looking at the pump/wiring for a fault.

 

[Agile]

Power the pump from a separate lead fused at 3 A from a socket.

Tony

 

[the1bandit]

OK thanks both. Back to the pump it is.

I have asked an electrician to come tomorrow night (another friend) and he is also qualified to look at boiler faults. Hopefully he will find something.

Thanks again for your time and input - much appreciated.

Paul

 

[Agile]

I have asked an electrician to come tomorrow night (another friend) and he is also qualified to look at boiler faults. Hopefully he will find something.

Paul

So he is registered with Gas Safe?

 

[the1bandit]

Hi all,

I thought I would give you an update - it's all working again!

I told my plumber your last few posts about the pump again and when I was down the shops he had it running without tripping but the pilot wouldn't work correctly (one step closer).

Then after changing the flow valve (2nd change) it all was working again.

I asked what he changed on the pump and he was reluctant to tell me (maybe he didn't put the replacement in correctly....!)?

Anyway, hot water an heating again with no trips. Thanks again everyone, I really, really appreciate your comments.

Paul Morris