Water leak from boiler after torrential rain

General_query

Hello,

On Sunday evening we had a severe thunderstorm and unbelievable torrential rain.

When we went into the kitchen water was dripping out from under the Logic C35 combi-boiler, which was worrying enough, but luckily we had a bowl underneath as we store DIY stuff there.

Anyway, we turned the power off immediately. It stopped within 2 hours of the torrential rain and (touch wood) hasn’t leaked / dripped again.

Googled it and it seems its quite common for this to happen during severe prolonged heavy rain that it can enter though the flue on the outside of the wall into the boiler. All the gutters were overflowing - as were all the neighbours due to the sudden storm, but we have no gutter pipe above the flue as it’s on a gable (end?) wall, so it's not poured out of that then down into / onto the flue pipe, then inside.

Don’t judge as we didn’t want to call anyone out as 7pm Sunday night and Bank Holiday Monday as that would have meant out of hours call out charges on what could already be a big repair.

So, I emailed (then spoke to) a Gas Safe registered engineer recommended on a local Facebook and he also explained it is probably the sheer quantity of torrential rain that has fallen that had entered the flue, and if it has stopped leaking / dripping then all should be well. Explained about the external flue and possible electronic damage but he seemed convinced it would have just been that amount of rain, he personally wouldn’t come out as if everything is fine when we turn it back on and no error messages it would have been something to do with the condensate drain. Might sound iffy but has helpful and nice. He could have said I’ll come and look, nothing wrong and wanted £100+.

Second contact was with a big local company (again Gas Safe registered) with lots of employees, who offered no advice / suggestions with an hourly rate of £96 an hour without any parts etc and a huge T&C list with this and that on it. So they would come but it would be a minimum £96 just for them to turn up.

Waiting to hear from another big local company as they weren’t answering the phone.

Nobody wants to spend especially on repairs and call outs etc, but as much as I liked the recommended guy, what if he is wrong and there is some kind of electrical damage?

Of course big firms will come out as they have the manpower (and overheads) but they are all going to be £100+ an hour before any parts that need fixing / repairs are done.

We just want someone to check the seal / flue fitting outside and also take the boiler cover off and check there is no damage and nothing wrong by the torrential rain that came in.

Any advice please? Although I think I’ve answered my own question.

Thanks.

General_query

The other "big" local company who weren't answering the phone have just replied repeating what I mentioned:

"Good Afternoon,

 This does sound like the rain has come in through the flue in the down pour we had . The boiler is ok to put on if you would like on of our engineers to attend we charge £75.00+vat per hour .

Regards"

So £90 a hour for them 😕

MyRealNameToo

Presumably its a horizontal flue in which case it should have a fall of circa 3 degrees so any water that gets in, normally the condensation of the exhaust but also rain from the outside, falls out rather than back to the boiler. Ifs all well and you have a decent fall no volume of rain should be sufficient to cause the water to get back to the boiler (highest rain fall ever recorded would be about 20,000th of the level of rain required to overcome 3 degrees)

If the flue is partially obstructed, if there is a broken seal etc and therefore water did get in the flue and back to the boiler it should go into the combustion chamber and through the condensation trap and out the waste pipe not overflow.

Did you check to see if the outside of the flue was wet? If it's travelling outside rather than inside?

Certainly worth checking that the fall on the flue is there as it should be, look at the seals around the flue and the wall

Exodi

Should this go in the https://forums.moneysavingexpert.com/categories/praise-vent-warnings board as I'm not sure of the question -

You seem to be worried about doing nothing "what if he is wrong and there is some kind of electrical damage?" but simultaneously complain about paying someone to come out at look at it?

"We just want someone to check the seal / flue fitting outside and also take the boiler cover off and check there is no damage and nothing wrong by the torrential rain that came in."

How much do you think they should charge (if at all - I note the use of the word 'just')? I have a lot of sympathy with tradespeople on this, as even if there's nothing wrong, you're still paying for their time, experience, fuel, insurance, etc.

grumpy_codger

https://forums.moneysavingexpert.com/discussion/comment/82122055#Comment_82122055

its a horizontal flue in which case it should have a fall of circa 3 degrees so any water that gets in, normally the condensation of the exhaust but also rain from the outside, falls out rather than back to the boiler.

I think it has to be opposite for a condensing boiler - the condensate (slightly acidic) has to leak back into the boiler - and so would the rainwater. If so and if the chimney was installed correctly, I think the rainwater got into the air supply pipe and then into the combustion chamber.

MyRealNameToo

https://forums.moneysavingexpert.com/discussion/comment/82122064#Comment_82122064

They will be acidic in both cases as carbonic acid comes from the high level of CO2 and the water vapour but you are right, if its a condenser then yes the flue runs to the boiler and the boiler is designed to be able to deal with a much higher influx of water. Still shouldn't overflow but may point to a blocked trap rather than a problematic flue

michael1234

https://forums.moneysavingexpert.com/discussion/comment/82122064#Comment_82122064

I'm not a gassafe engineer and I won't go into why I know, but that is correct. Unlike most things we fit in our houses that have pipes or cables going outside, this is either fit level with an internal drain back towards the boiler or if not perfectly level then a slight fall back to the boiler.

moneysavepound12

Gosh that's awful, a similar type of situation happened in the office I work in, where we had a wet patch on the floor develop last week.

General_query

https://forums.moneysavingexpert.com/discussion/comment/82122055#Comment_82122055

Thank you.

I have attached some photo's. The first one highlighted in red is where the water was coming from during / after the torrential rain, this seems to be the bottom of the combi boiler condensate drain? So it could just have overflowed from the force of the rain blowing in, but I'm not a boiler engineer.

The other shows the location of the flue on the external gable wall above the kitchen window. Have no ladder so can't check it unfortunately.

Boiler was installed in 2022 as part of some Government improvement grant for my partner's mother (who has since died). We weren't happy at the time by the quality of the work done, but apparently it was done for free, no excuse for shoddy work.

Yes, the brickwork needs repointing. The house was built in 1926 and she was ripped off by two separate pointing companies.

So we are a little wary of just picking someone off the Gas Safety Register. The installers of this boiler must have been Government approved at the time.

And to the other poster, yes we know we have to pay someone nearly £100 an hour to get it checked but not having someone turn up who will refuse to put a ladder up and inspect the flue exit / opening outside and demand £100 for just taking the cover off with only visual checks

Thanks,

mazjohn108

I have had similar problem with rain coming in through flue under certain weather conditions. Boiler is now 12 years old and this has happened probably half a dozen times. I was told newer flues are slightly different from mine and would deflect rain better. I live in 2nd floor flat and have been told that it would cost £1000 for scaffolding to change the flue!

General_query

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