Potterton Pro Max Boiler - allergic to cold weather

[HopelessBoiler]

Hello!

This is my first post, but I have to say, I'm desperate!! My house was built in 2008 and a Potterton Pro Max Boiler was installed by the builders. It works BRILLIANTLY ... until the weather gets cold (once we get below zero) when things go horribly wrong.

I've been away for a few days over Christmas and come back to a FREEZING house (the temps have been well below zero here for several nights) and the boiler on but displaying the usual E125 error message, so not actually working. I'd left the heating on low whilst I was away, to avoid frozen pipes etc, but this is foiled if the boiler keeps hitting this E125 problem. I can reset the boiler and it comes back on without too much of a problem.

Over the years, BG have been out and replaced all the usual stuff, pump, PCB, valves etc etc, which has made no difference at all - but they've never actually found a fault and the engineers admit they don't have a clue what the problem is. I even asked an independent plumber to come out once, he couldn't find a prob either.

The condensate pipe is inside the house and drains to under the sink, I believe.

Can anyone shed any light on what is causing this problem, please?

Many thanks!!!

 

[twgas]

Is hot water ok?
Do you have to reset several times before it works?
Do you have plastic CH pipes?

 

[HopelessBoiler]

Hi!
Thank you for your reply!
No hot water when boiler goes off, but it comes back when I reset the boiler.
Sometimes it will reset/start 1st time, sometimes it takes 2 or 3 attempts.
I'm less sure about the pipes, the condensate pipe (if that's what you call it!?) Coming from the boiler is plastic, as far as I know everything else is copper.
Hope I'm not sounding REALLY dim now!?
Thank you for replying!

 

[steve32]

Is it locking out when it comes on in the morning or at various times during the day

 

[HopelessBoiler]

Hi Steve32!
No it can happen at anytime. Whilst I was away I left it on 24/7 but turned down low. It does seem to happen when it comes on though, if it comes on it seems to stay on, it's the initial surge of "coming on" that seems to knock it out, it doesn't always happen, but when it does the weather is always below zero, if that makes sense?

 

[steve32]

Has the gas pressure at the gas meter and combi been checked when the temperature is below zero.

 

[gigz]

E125 is circulation problem. Is the system water clean ?

 

[HopelessBoiler]

Steve32
I'm not 100% sure of the answer to your question, I seem to recall BG mentioning gas pressure, but maybe that's something I need to query specifically, thank you!
Gigz, yes, I believe the system water is clean, more than one BG engineer has been excited at the prospect of being able to sell me a "power flush", but on checking they haven't been able to find anything to suggest it would help! Thanks for the thought, though!

 

[gazdaz36]

What sort of system have you got? One thought is that if the boiler is firing for frost protection because it's cold and from memory I don't think the pump is wired back to boiler on this model it might be calling for heat but has no circulation as the pump is not going. Or if it's on an s plan the valves might not be open and there's insufficient flow through the bypass to make the flow switch on the boiler

 

[HopelessBoiler]

Thank you gazdaz36, to be honest, I don't know the answer to your question!!! I'm very grateful for your reply - I'm thinking of emailing BG/plumber with the suggestions put forward to see if they can come and look at it and try to sort it finally - it does seem odd that it's relatively easy to relight - the problem of course is when I'm not here to relight it!!!!

You may have realised I'm completely clueless about all of this, genuinely clueless - I was just wondering if anyone else had come across the problem and could shed any light on it - don't worry, I'm not trying to fix it myself!!!