No power getting to a Baxi boiler

[Pearlyman]

I thought this photo might be useful - it shows the relative position of the power supply, timer and boiler, so should help you orientate yourself:

View media item 66769
2 cables go from the power supply up to the wiring box (which is located in the airing cupboard above the utility room).
One of these connects to the power supply directly, whilst the other is the link to the timer...

The power supply then connects to the timer, via a single white sheathed cable containing brown, blue, black x 2 and Y/G - plus a single yellow.

The timer connects to the boiler via a white cable which contains the same 5 wires as above - but the 2 blacks are unused...

 

[EFLImpudence]

The brown is actually in HW on (along with a black - which goes to the wiring box. There is just a black in CH on - which also goes to the wiring box).

Oh. my mistake but the same goes for it being in HWon. It should not be.
Black correct.

The brown in HW on goes to the live in the boiler

It should not.

The blacks in the timer go to 4 and 6 in the wiring box - as you would expect.

Correct.

The blue connected to the 2 oranges, is the one that you can see connected to the Y/G in the power supply pattress !
It then goes across to the timer, where it is connected via a connection block to the Y/G for the boiler !

I suspect someone has got confused by using the G/Y for a live and then forgetting - remove G/Y from the Blue

The brown from the pump also goes into 10 - as you would expect...

Good.

2 cables go from the power supply up to the wiring box (which is located in the airing cupboard above the utility room).
One of these connects to the power supply directly, whilst the other is the link to the timer...

The power supply then connects to the timer, via a single white sheathed cable containing brown, blue, black x 2 and Y/G - plus a single yellow.

That's confused me slightly but if there is another cable going from switch to wiring box this is all you need -

The colours do not matter (apart from G/Y is earth and only earth) so it may not correspond exactly but -

Untitled

• EFLImpudence
• 24 Sep 2013
• 1

I would recommend you rewire the box with one length of ten connectors.
Cut the wires to length (as long as there is some spare cable) and do it neatly.
As I said, it is not difficult if you wire one cable/part at a time.
You will see that both valves are wired exactly the same except one is switched from the tank stat and one from the room stat.

 

[Pearlyman]

Good evening EFL.

I have connected everything as per the ‘S’ plan diagram – though I have not dared to make the circuit live yet !

It all makes perfect, logical sense to me – provided I ignore the photos !

Of course, I am struggling to do that (more so than you are I suspect !) – because I know that that I have changed around the earth and the live in the boiler !
How could the previous set-up possibly ever have worked ?

Is there any way that I can go for a ‘controlled switch on’ (eg. I disconnect part of the circuit and test things in a ‘live’ state before connecting everything up fully ?).
If I have got it horribly wrong and mixed up the live and the earth in the boiler, what will be the consequences ?

I know this all sounds like paranoia – and that an electrician would just go ahead and make the changes I’ve made – but I do have the additional bit of knowledge concerning how things used to be…

Just to confirm: the blue from junction 10 now connects directly to the live (brown) in the boiler (so the brown is no longer connected to HW on in the timer); and the earth (Y/G) in the boiler now connects to the earth in the timer…

 

[EFLImpudence]

Good evening EFL.

Hello.

How could the previous set-up possibly ever have worked ?

It may have "worked" as in run but I cannot see how it operated properly.

Is there any way that I can go for a ‘controlled switch on’ (eg. I disconnect part of the circuit and test things in a ‘live’ state before connecting everything up fully ?).

Not really with anything other than 240V (you should not anyway) because the parts will not work.
With the switch open you should test for continuity from one end (supply/timer/boiler) to the wiring box and more importantly continuity between earth conductors throughout and metal parts but NO continuity between earth and anything else.

If I have got it horribly wrong and mixed up the live and the earth in the boiler, what will be the consequences ?

You can't mix up earth and live in the boiler. The terminals will be marked L,N,E.
It was mixed up before.

I know this all sounds like paranoia – and that an electrician would just go ahead and make the changes I’ve made – but I do have the additional bit of knowledge concerning how things used to be…

You could wire a light using G/Y as live, Blue as earth and Brown as neutral and take a picture with it working.

Just to confirm: the blue from junction 10 now connects directly to the live (brown) in the boiler (so the brown is no longer connected to HW on in the timer);

Good.

and the earth (Y/G) in the boiler now connects to the earth in the timer…

Good.
Of course if the boiler was not actually earthed (connected to earth) before because both the EARTH WIRE and Neutral were live and the Live was neutral then it would work but be very dangerous.

 

[EFLImpudence]

Ah. You're not the only one.
//www.diynot.com/forums/electrics/live-neutrals-reversed.377754/

 

[Pearlyman]

OK – I’ll give it a try – but tomorrow morning, when the children are out of the house !

I appreciate what you are saying about the previous set-up – but the boiler was installed by British Gas – and the electrics installed by a British Gas electrician.
No one else has touched them (until I took them off the wall !). If they really were set-up in a non-standard – potentially dangerous – way, it would be extremely poor (though, ultimately, unproveable).

Inside the boiler, there wasn’t actually a L,N,E – it was just an unmarked connection block. Though the G/Y connection continued with a G/Y wire which went into the heart of the boiler (leading me to believe that it was the earth).

If I have got something wrong, what are the likely consequences ?
Will it fuse ? Become live ? Blow up – or simply not work ?!

You mention testing for continuity in the completed circuit – how would I do this (with a multimeter ?)

 

[EFLImpudence]

I appreciate what you are saying about the previous set-up – but the boiler was installed by British Gas – and the electrics installed by a British Gas electrician.

You may very well think that is (what's the word?) but I could not possibly comment.
Do a search.

No one else has touched them (until I took them off the wall !). If they really were set-up in a non-standard – potentially dangerous – way, it would be extremely poor (though, ultimately, unproveable).

There is no question that connecting L & E the wrong way round can ever be anything but wrong.

Inside the boiler, there wasn’t actually a L,N,E – it was just an unmarked connection block. Though the G/Y connection continued with a G/Y wire which went into the heart of the boiler (leading me to believe that it was the earth).

There must be some indication. It would have come with instructions.

If I have got something wrong, what are the likely consequences ?
Will it fuse ? Become live ? Blow up – or simply not work ?!

Depends what you get wrong.
Don't get anything wrong. Double check.

You mention testing for continuity in the completed circuit – how would I do this (with a multimeter ?)

Yes, (and a long wire).

At the wiring box.
Switch OFF.

There will be a few ohms between 10 and 2 through the boiler and pump.

Very low ohms
between 3 and all metal parts (tank, pipes, maybe metal on valves).
between 4 and 5 only when room stat calling
between 6 and 8 only when tank stat calling

Open circuit
between 1 and all terminals when everything off.
between 2 and all terminals except 10 when everything off.
between 3 and all terminals at all times.

You can see and work it out from the diagram.

 

[Pearlyman]

OK.

Wish me luck - I will switch it on tomorrow morning...

Needless to say, I will post my result (assuming there isn't a big bang )

 

[EFLImpudence]

Good luck (although luck doesn't come into it).

 

[Pearlyman]

View media item 66823
EFL, you are a genius (I assume you can see the yellow and green lights on the boiler)

...and even if you are not a genius, you have the patience of a saint (which is almost as commendable).

I rechecked the wires inside the boiler this morning - and then checked every connection block in the wiring box.
It was all as I expected - so I switched things back on - and the boiler burst into life !

I remain bemused as to how it was working before - but I will have to let it go (even if I am now suspicious of British Gas).

Unfortunately, the boiler only ran for a few minutes before it stopped - but I think that it being caused by an issue with the pump, or maybe some air in the system (presumably not helped by it being inactive for a month). Whatever, it is something that British Gas should be prepared/able to sort out...

One final question, whilst I was putting the power supply pattress on, I manged to nick the live feed from the ring main. It really is a tiny cut - but it has broken the sheathing and I can see copper.
What is the best way for me to deal with this ?

 

[EFLImpudence]

Untitled

• EFLImpudence
• 20 Jul 2011
• 1

Woohoo!

Very good, well done.

Wrap your nick with self-amalgamating tape.
As the name suggests it merges and ends up as one piece of rubber (not sure if it actually is rubber).
http://www.toolstation.com/shop/Self+Amalgamating+Repair+Tape/p23876

 

[Pearlyman]

I couldn't have done it without you (but you already know that !).

Incidentally, non of the electricians that I contacted have even got back in touch with me. They just don't seem interested in solving problems...
It's quite shocking really ! (if you'll excuse the pun !!).

The system is now running fine - there was just a lot of air in it. It was drained down to enable a couple of rads to be removed as part of the work and it hadn't been used since...

That self-amalgamating tape looks just the job - I'll get myself a roll tomorrow.

 

[EFLImpudence]

I couldn't have done it without you (but you already know that !).

Thank you.

Incidentally, non of the electricians that I contacted have even got back in touch with me. They just don't seem interested in solving problems...

I don't know why.

It's quite shocking really ! (if you'll excuse the pun !!).

The system is now running fine - there was just a lot of air in it. It was drained down to enable a couple of rads to be removed as part of the work and it hadn't been used since...

Good.

That self-amalgamating tape looks just the job - I'll get myself a roll tomorrow.

Yes. It's stretchy, pull it out to three times its length when you apply it.