Leaking boiler?

matty_hunt

Hi. I have a Worcester Greenstar 15Ri condensing boiler on the wall in my kitchen. At the base of it, the paint on the wall is peeling off. I tested with a damp meter and it was off the scale wet. Its just this one patch. Wall is dry above and a little damp below. There are no pipes that come through the wall, other than the flu and it appears dry around that. Any gas engineers or anyone with knowledge out there that can shed a light on where the water maybe coming from? Could it be squirting out onto the wall from somewhere? Enough to soak it but not enough to be visibly running down the wall. There is no obvious issue on the outside. Cheers.

Bendy_House

Is it a 'system' boiler, ie sealed, pressurised and with a gauge? If so, has there been any pressure drop?

Another possibility is that the condensate trap is full of sediment, blocked and overflowing. They shouldn't leak, but mine did when the trap became blocked with grit, because the washer inside the screw cap was perished...

I'm not going to suggest you check this as it's almost certainly a GasSafe task.

If it is 'condensate', it'll be mildly acidic, so will tend to cause more damage than system water. If you turn off the mains power to that wall socket circuit, remove the faceplate and have a gander behind it, if it's a metal back box, does it have visible corrosion on it?

matty_hunt

Thanks for the suggestions. It is an open vented system so no gauge. The trap looks fine and doesnt feel wet. Checked the plug socket. There was no sign of corrosion at all, which was surprising. Might have to take some bricks out of the external wall and have a look inside.

Bendy_House

That's another possibility - a leaking seal around the flue where it goes out through the wall.
Photo?

matty_hunt

Thanks. will try and have a poke around over the weekend.

Bendy_House

Gentle with the pokes

Could you post a photo of the flue as it exists the wall? If rain gets in there it could run down the outside of the pipe and, since it slopes down back the the boiler, could end up on the top of the boiler casing. How far up under the boiler can you see? Can you determine where the stain begins?

Of course there are all sorts of possibilities, including a straight-forward leak. My boiler developed a crack in a hard plastic component, and the water sprayed out at pressure. That was pretty obvious, tho'...

Bendy_House

Ah, the flue is obvious at the top, so any 'external' leak would be obvious there. Unless, I guess, any water exited on the inside of the internal wall. 

Is that a gap in the internal flue collar? If so, the next time it rains, could you pass a piece of wire or similar, with a pad of kitchen paper on the end, up there, sliding it in contact with the underside of the flue?

daivid

I'm not a GasSafe engineer, and I'm sure this counts as a job for one. As the case forms a seal around the boiler safety checks are needed any time it has been removed (and put back). I'd recommend you get an engineer to service your boiler, fix the leak if it is the boiler, and make sure it is safe.

That said I understand wanting to know where it is leaking from. My WB has leaked 3 times in 3 years - two pinpricks in manifolds and a failed rubber washer. With the manifold leaks the leaking was most active under certain conditions and was could be heard very clearly - hissing sounds. So you could try listening (and shining a bright torch which would help show the water mist) whilst you run the hot tap, and then after you run the hot tap. My latest leak was definitely after running the hot tap (when pressure was highest). The failed washer IIRC was less dramatic, just a bit of water running down the wall - the 1st manifold leak soaked through the whole airing cupboard contents and down to the floor boards, the 2nd manifold leak filled the plastic dish I keep under the boiler now - I check very week or so when I put away the towel wash.