I know I need to call someone out but thought I would try here first to try and understand my issue a bit better. Gas man has been out to look at central heating not working correctly and diagnosed the fault as power loss and swapped polarity on supply from fused spur to junction box in airing cupboard.
The only electrical wiring changes that have happened in the last year are me adding in an extra security light outside sometime ago but heating has not been affected till now. I just joined into the existing outside wire using a junction box, lives, neutrals and earths are all matched up in the junction box and outside lights are working ok.
Happy to admit I screwed up but I’m not convinced that it’s my diy that’s likely to of been the cause of the supply problem.
Its quite an old house with wiring all over the place but I would of expected lighting and heating to of been on separate circuits so not sure if is my fault or not. Could it be a parallel /series connection type thing ?
As I say I will need to get a sparky out but trying to find one who phones you back is proving tricky for now.
Any ideas gratefully appreciated.

Its possible to do weird shit when you add a spur to an existing ring circuit if you haven’t understood how its all wired up – I’ve even had professional electricians do stuff that doesn’t make sense especially on lighting circuits. However your boiler shouldn’t be on the same circuit as your lights so it would be very odd to have this issue, and even odder for it to emerge many months later. Could something have developed a fault (water damage?) that might cause it?

I’m surprised its being described as power loss AND “swapped polarity”. I assume he means that L/N are reversed (I think polarity in an AC circuit technically is something different but he’s a gas man!). I don’t see any obvious reason why this would stop the boiler working, I don’t see how it can have no power and be reversed (but I might be being dumb).

If you have a multimeter a notepad and coloured pens the same as your cables (red/black blue/brown) its usually not too hard to work our what’s actually going on if you are methodical.

Swapped polarity, and it has been working until recently?
It’s possible, as boilers are made for europe wide use, so may be OK with wrong polarity.

But, just swapping the polarity back isnt going to fix a fault that has just appeared.

Give me some more details of what has gone wrong with the boiler.
And, yes, it is possible that the outside light is off the same circuit as the boiler, but that isnt really an issue, and it shoudlnt affect the boiler in any way.
Oh, and where are you, someone who can help may be close to you.

Polarity usually stops flame rectification working.

And if polarity swapped, why didn’t he swap it back? Seems a wierd thing to me. If it was working and nothing has been changed then polarity changing could only happen from incoming supply I would imagine. And that would show up in other things I would imagine.

Yes where are you there are few on here dotted around the country who might be able to help.

Happy to admit I screwed up but I’m not convinced that it’s my diy that’s likely to of been the cause of the supply problem.

I once wired two lights in a room flicking the switch one stayed on the other went on and off 🤣.

Easy to check if the security light and boiler are in the same circuit, just flip the breaker for the light, you must know that one as your not dead when you fitted it, then see if the boiler is powered off or on.

Thanks
It is indeed weird. I’m pretty sure its nothing to do with anything I’ve done (if I turn off the fused spur to airing cupboard thus isolating heating the outside lights still work) I may of misunderstood what gas man was saying as my mind was admittedly a bit elsewhere when he left. Once I have a sparky I need to get a contact number for gas man (something I stupidly forgot about and not sure if British gas will give me his number anyway) to explain problem to him and cut out me the confused middle man.
Boiler comes on , hot water works, original callout was problem relating to radiators not warming fully and was something to do with diverter valve so guessing its a voltage supply issue to that possibly. He thought that maybe the issue was between the supply spur and the junction box and a new supply wire was possibly required. As you say he is a gas man and of course doesn’t do the electrics.
Seems odd to me that if the input is compromised then why does the hot water still work ?
Located in North Hampshire and happy to pay to get it fixed just really annoyed with myself for focusing on the “need an electrician to sort the supply” rather that what he was saying, I’ve clearly missed out on the important details.

So it’s a combi boiler?
Diverter valve is a common failure, they are around £50-100 as spare parts, and its a pretty quick job to fit it.
If the hot water is working properly, then I’d say the boiler is working correctly, but with a fault. The ‘polarity’ issue may be a red herring.
However, when the diverter valve fails, it usually stops the hot water getting anything other than luke warm. You see, when you open the hot tap, the boiler senses a loss of pressure on its hot water exit, so open the valve to let hot water through, as it does this is fires up the boiler to heat it.
Now, if you are only getting luke warm water, and luke warm radiators, thats pretty close to a sure sign of the diverter valve seals having broken/split.

Yes combi system, would a polarity change be needed to alter the diverter rotation around maybe that’s what he was on about but where would that change occur ? As you can see I’m a numpty.

If it is the diverter valve, then it will likely be the seals inside have gone. Seal kits are available for most valves.
However, there is a small motor or solenoid for it too. If that has gone, new valve required. A new valve is probably the best thing anyway, they do wear out.
I’d say it wasnt an electrical fault, it is an internal boiler fault, and the gas engineer will know when he fault checks it.

I had an issue on my combi and I called out a gas safe engineer for a repair and to service it, was an intermittent issue which I thought was related to the PCB.

His diagnosis was dunno could be anything chief, you need a new boiler as I’ve never seen one of these🙄, it’s a Halstead clunk whoosh type of boiler not terribly modern but easy to work on.

So I dug out my kit off the van and traced it to a dry solder joint on PCB ordered a replacement of ebay 2nd hand and that was seven years ago.

alanl

He checked that the boiler cut in by pulling off hot water from tap and then spent the rest of his time in the airing cupboard. You must be right it’s diverter related but he deffo mentioned polarity reversal somewhere and I would of hoped he would know about a possible mechanical failure. He left the diverter unplugged in the middle position so it does both water and heating to keep us going and said to call back after sparky visit. I will call British gas in the morning and try and get to speak to him and clarify things before I do everyone’s head in.

Once again thank you all.

Possibly a bi polar transient fault with the flux capacitor, affecting the inertial flow of electrons.

get a man in to fix it.

Central heating boiler taking electrical supply from lighting circuit is normal. It’s only powering the igniter plus programmer, not heating the water, the gas does that.Draws minimal current. Dodgy connection somewhere, most likely a junction box. A sparky will trace the problem very quickly.

A sparky will trace the problem very quickly.

Hopefully, however getting one to actually call you back is proving tricky.

Bit of an update, all fixed, warm house and pleased to say nothing to do with my additional security light installation.

Managed to get a sparky out who quickly confirmed polarity was indeed reversed because the fused spur out lines were wired incorrectly. Still not sure how it happened as it’s been untouched for years so amazed everything still worked. Gas man been back and diagnosed intermittent programmer box not always doing its thing so not turning the diverter valve to the rads.

Thanks for all the advice.

Glad you got sorted, I’ll add this for the benefit of a future search.
Combi boiler worked when we first bought the house, but shortly after it didn’t produce any hot water or heating, the control panel worked, the gas was there, 240v present and correct, but it couldn’t run.
Turned out the neutral wire in the spur which supplied the boiler and two bathroom radiator heater elements had broken deep in the wall.
Enough current leaked out to earth through the heating elements to provide a ‘neutral’ that was only able to support the current draw of the PCB and panel, but not the pump.

all fixed, warm house

Glad it’s sorted Muke