I've got what looks like an overflow pipe at the side of my house that's dripping water, but I'm not sure what it is.
There's no boiler or toilet on the other side of the wall where it is, and the boiler isn't a condensing model anyway.
Here's a photo:
Any idea what it is?
A pipe! A photo of the other side of the wall might be more useful ...
What IS on the other side of the wall? Is this the lowest point in your central heating system perhaps, the outflow for anyone draining the system?
Maybe it's for draining some other set of pipes?
Presumably a pipe so low isn't the overflow for any water tanks you might have in the attic (if you have an attic) but you'll know what pipes are where better than I do.
I've measured it up, and it looks like it's just above the level of the ground floor and behind some kitchen units where there's a gas hob.
There's nothing obvious that it would be linked to, and I'll need to get behind the kitchen units to work out what it is.
that is a pressure relief pipe.
Notice how it folds back onto the wall.... this is a safety measure so that people dont get direct jets of hot scalding water onto them
Basically you either have a pressurised heating system or a mains pressure hot water system.
Your pressure relief valve has either opened due to an overpressure condition or it itself has failed, causing a slow leak.
Eventually you will lose either heating or hot water at some point.
Yes, that's it! I've found a dripping tundish in the upstairs airing cupboard with the hot water cylinder in it. That must somehow route down inside the wall and out to that dripping pipe.
Thanks for your help.
Probably not now used. Been replaced by a vegetable oil pipe. :-)
Well in my old house there is a small bore pipe connected to the hot water cylinder that goes up into the loft and joins the very long overflow pipe from the cold water tank, and sometimes people have seen the odd drip out when there is nothing wrong with the cold water tank ballcock and valve, so I always assumed it was condensation from hot water in the cylinder pipe condensing in the overflow and trickling out of the end.
Brian
Depending on the type of cylinder you may just need to replenish the air bubble in it.
Make and model would help
If it is some sort of mains pressure heater the pressure relief valve sometimes opens on the heating cycle if the water boils and increases the pressure
I've found the problem now, thanks.
It's a weeping 8-bar pressure-relief valve on the cold-water inlet of a magaflow hot water cylinder. The PRV must be faulty, as my water pressure is only about 3-bar, and this PRV is downstream of a 3-bar pressure reducing valve.
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