Water coming in flue pipe after boiler installation

[quelsurprise]

Hi there, very similar to Ann we've been having the exact same problem.

I have a Remeha Avanta Plus 28C condensing boiler and for the past 3 days I have had no heat or warm water. This has finally been resolved just this afternoon when an engineer came out to replace the PCB as it was fried.

Saturday night I could hear the rain hitting the bedroom window, and the horizontal flue facing the same direction below. I have had the boiler approx 18months and when the rain and wind blow drive in that direction I have noted a few times water dripping from the bottom of the boiler onto the floor and when i've taken the front off, it was dripping from the pipe connected to the flue. I asked the engineer what I can do about this, he checked the flue, said it was installed correctly and said sadly it's one of those things.

Is there anything I can do to stop this happening again? Can you buy a "rain cap" as such, or some form of protection to put over the flue stop the water blowing into it?

Thanks for any help, its much appreciated. I'm at a loss.

 

[ann]

Thought I would let you know how we have got on. We had another plumber come and have a look at it. He said that the flue outside was angled upwards at quite an angle, and said that he would alter it slightly. He said that the drain inside the flue was angled so that the condensation would run back okay. I am wondering if the rain was too much for the drain to cope with and eventually leaked out through the boiler, but now the flue is not angled so steeply upwards anymore, it has cured it. Watch this space.

 

[oldplumber]

I installed an avanta plus combi recently and the flue had water ingress from a blocked gutter overflowing onto the flue. The houseowner cleared the gutter and this has stopped the problem up to now

 

[jontris]

Was there ever a solution to this problem? I also have a Potterton combi boiler installed in November 2009 and seem to have exactly the same symptoms.

Some posts seem to suggest that Potterton have simply not made provision for rain water trickling back through the flue (ie through the inside, not along the outside) and nothing can be done. That would be a depressing scenario.

 

[Blackcatgas]

Was there ever a solution to this problem? I also have a Potterton combi boiler installed in November 2009 and seem to have exactly the same symptoms.

Some posts seem to suggest that Potterton have simply not made provision for rain water trickling back through the flue (ie through the inside, not along the outside) and nothing can be done. That would be a depressing scenario.

Post number 22 🙂

 

[prs1]

All maufacturers have already made provision for this on threr vertical flues,it wouldnt take much would it!
lets face it its not like they charge that much for a boiler is it.
You wouldnt put up with it on yer new ford "sorry sir its only when the wind is blowwing ssw ! Ba5t!!DS😡

 

[jontris]

Thanks for the replies but I'm still confused. My installer told me that the flue must point upwards a little. This presumably means that water can flow back. I suppose it depends how exposed the flue is and the strength and direction of the rain and wind.

My question: what is supposed to happen to this water? Does it just drip out of the bottom of the boiler, as described in several posts? Or should it get collected and flow safely away down one of the escape pipes?

 

[jontris]

If it's of interest, my researches suggest rain water is getting inside the flue and flowing back into the boiler. On the 'gas side' (ie inner cylinder) that is no problem - it just goes back into the condenser. On the 'air side' (ie outer cylinder) it has nowhere to go and just drips out the bottom. The Potterton technical help line agreed that this could happen. I am pursuing the matter with Potterton as to me this mean that their flue is not fit for purpose. After all, flues must protrude from buildings and it does rain from time to time.

 

[Billy Bob Bob]

well tbh i have installed a mixture of potterton performer and golds and have never had this problem the flue is a good design i would strongly suggest this is a installation fault and bg have distorted or broken the rubber seal on the air intake

 

[danielp]

i have had it on a glowworm ultracom its where the outer flue is a butt joint and isnt really a water tight seal

 

[jontris]

Well, it's definitely rain water. This only happens when it's raining. I've also proved it's not coming along the outside of the flue. A cloth tied round the flue as it enters the boiler remains bone dry. It's not coming down the gas side. I've got one of those directional extensions pointing downward. It must be rain water flowing back down the flue on the air side. Properly installed where would this water go?

 

[Billy Bob Bob]

Well, it's definitely rain water. This only happens when it's raining. I've also proved it's not coming along the outside of the flue. A cloth tied round the flue as it enters the boiler remains bone dry. It's not coming down the gas side. I've got one of those directional extensions pointing downward. It must be rain water flowing back down the flue on the air side. Properly installed where would this water go?

the water would go to the heat exchanger then down the condensate pipe what potterton is it?

 

[jontris]

OK, so is it the same whether it's the gas side or the air side? Potterton seem to think that water on the air side would just come out the bottom.

I presume they think they've designed the flue so that water couldn't get in but I've tried pouring water on top of it and seen that it can curl inside the vents and drop inside.

It's a Performa 24 HE btw.

 

[Billy Bob Bob]

right then,i have installed 156 performas unless the flue elbow seal is damaged or mis aligned there is no way water can come back in,the flue is a good design and i have never had this problem,back to your installer,somethings a miss

 

[jontris]

I'm really grateful for the interest you're taking.

Are you saying that rain water can't come back along the inside of the flue and back into the boiler? Or are you saying that it can come back but it wouldn't drip out of the bottom. Either way you seem to be saying that Potterton have got it wrong about their own boiler.

BTW I have had my installer back and he insisted that the water must be coming along the outside of the flue. I knew it wasn't and I've since proved it.

 

[tamz]

Every condensing boiler made by every manu has the flue fitted at an angle of approx 5 degrees sloping back to the boiler so that the condensate in the flue gas (from the inner pipe) falls back to the boiler and then to drain.
This means that the air intake (outer pipe also slopes to the boiler therefore any driven rain will enter the air intake which leads to the inside of the boiler.
ALL the manu's know this could happen but they are stuck between a rock as the condensate (acidic) must run back to drain.
BTW non condensing FF boiler flues sloped away from the boiler to stop this happening and on older balanced flues, it just happened anyway although nobody noticed for a good few years until it started rotting.

 

[stevetheplumber]

i can see this being a major problem in future as rain water entering through the air inlet has nowhere to run to probably going to need redesign to allow water to enter the condensate pipe work via some kind of seal
in theory this water could be drawn into the fan

 

[jontris]

Thanks again respondents.

So ... the answer is that rain water CAN get back into the boiler. On the gas side it goes back into the condenser and isn't a problem. On the air side it has nowhere to go but down. My installer laughed at me when I suggested this might be happening.

My flue is high up and exposed, so I may be more prone to the problem than most. I suppose one solution would be to build a cover to protect it from the rain.

 

[rob jefkins]

Just had to replace a fan on potterton 70HE because rain water had come in through the flue and blew the fan motor. Obviously a common fault here.

 

[sparky]

A stab in dark but could the inner flue pipe have been cut accidently when cutting flue down? Have seen this before with water coming into boiler.Havent read all posts so apolagise if this has already been mentioned.