On 13/11/16 16:44, Munch wrote:
Bob Minchin presented the following explanation :
Munch wrote:
I recently noticed a damp patch on the concrete floor at the front of
the house. The boiler is installed in the loft and the condensate drain
has been poked out of the loft to empty the condensate onto the roof,
where it makes its way down to the guttering and off on its merry way.

I assumed that the guttering was full of leaves and just needed clearing
but it's clear - then I discovered that the water/condensate is not
getting as far as the guttering and is actually dripping from the
woodwork. The end of the condensate pipe and the location where I've
seen drips forming are both arrowed in the two photos below:

http://i137.photobucket.com/albums/q...oo/dormer1.jpg

http://i137.photobucket.com/albums/q...oo/dormer4.jpg

What's likely to be the problem? What's behind that woodwork and in the
'overhanging' section - just empty space?
At the risk of stating the blindingly bleeding obvious you have a leak
somewhere.
Maybe the outlet has blocked and the pipe work has not been properly solvent
welded or repeated thermal movement over the years has parted one of the
joints.
You need to get up there and trace it through or maybe easier fit a new pipe
run as trying to solvent weld old dirty pipe might not be 100% successful.

No, there's no leak in the loft. There's a short drop from the boiler,
an elbow and then about 4ft of pipe that goes out. Everything is dry in
the loft and condensate can be seen coming out of the end of the pipe
onto the flashing. It's once it gets there that it's not running down
the flashing and/or tiles as far as the guttering and is coming out of
the woodwork instead.

It clearly has been working until fairly recently as the acidic condensate
has been running down the tiles. Not sure what the long term effect on the
concrete tiles has been - wonder if they have gone porous?

Now that's a possibility I suppose.

A less pretty but sounder solution would be to run pipe down the roof slop
and direct it into the gutter. If the tiles have become porous, painting that
strip with bitumastic paint might save having to replace them.

Thanks Bob, good idea.

Yes, but don't do what the installers did with my neighbour's condensate
pipe. The idiots extended it almost to the bottom of the gutter. When it
snowed, and that partially melted in the gutter and refroze, the bottom
of the pipe was below the surface of the water and got blocked by ice.
It didn't take long for the boiler to detect the blockage and turn
itself off on one of the coldest days of the year!

--

Jeff