Are there any plumbing savvy people around?? (possible water leak)

[Missnearlyvintage]

Hi everyone,

I'm not sure if my central heating system is leaking water somewhere and don't know how I can find out. I've tried calling our plumber but he's not responded and DH is out at work until 10.30pm and can't use his phone at work.

We've got a back boiler, and the heating system is gravity fed, with a header tank in our loft.

Our central heating pipes in the ground floor are all buried in our concrete floor slab, and we've had the misfortune of finding two pipe leaks in this pipework since we moved in four years ago.

The last leak was fixed in the summer and we've still got the hole in our concrete floor slab in the kitchen, where they had to dig to find the pipe and fix the leak. We've been waiting for everything to dry out and have workmen due to rectify everything in the new year...

Anyway, this afternoon I noticed that after looking quite dry for months, there is water in the bottom of this hole (the whole is 1.2m long, 10cm deep, 10cm wide with a pipe running through it). I've not noticed this before today and having had a feel around the pipe and a look I can't see water obviously coming out of the pipe in the hole. It's enough water that it beads on my finger if I put my finger on the bottom of the hole, but not a pool of any size.

I went up in the loft as I remembered DH telling me something about knowing if we have a leak, by finding out whether the header tank cold water inlet pipe is dripping i.e. re-filling, or not. I've looked and it is, so I'm not panicking that we have a leak again.

I just don't know what to do really. If it is a leak it can't be that big if related to the amount of dripping, as it's a drip every couple of seconds rather than a stream of water.

If anyone has any advice I'd be really grateful! Thank you!

as you've already had a couple of leaks from pipes buried in the floor, and the floor is getting wet again, I think it's to be expected that's where the new one is.

I wonder if the pipes are steel, or unwrapped copper.

I'd further suspect that all the rest of the old pipes buried in the floor are also corroding, and sooner or later will all leak, so really it should all be replaced.

Corrosion leaks sometimes start small. They are likely to get worse.

If the float valve is just dripping, it's currently a small leak. However this will rinse away any corrosion inhibitor chemical, and the corrosion will accelerate.

Thanks PigletJohn.

I couldn't get hold of the plumber today but will try and get hold of one tomorrow and let DH know when he gets in.

I've had another look, (and a look at a header tank diagram), and yes it is the float valve that's dripping - still the same as earlier on.

After the stress of 2 water leaks and now this, DH and I had said a while ago that if we had another leak the whole of the pipework underneath the floor would be isolated, and we would have drops installed instead, so it looks like that's the way we'll be going...

Just to check PigletJohn, is there anything else that could cause this dripping please? or is it more than likely just that we are losing water somewhere through the pipework as is the current thinking?

Thank you!

To add, the pipes are we have uncovered so far are copper, with a black coating on the outside, and lagging. The house was built 1972.

The leaks we've found thus far have been the result of compression joints failing. But I don't know if they are replacements for other compression joints, or used to repair small leaks, as the concrete floor slab had been dug up in those places at some time, and new concrete had been poured in those areas. We've been told that compression joints were never recommended to be installed in concrete flooring. I don't know if the rest of the pipework under the floor also contains compression joints - there are no other newer patches of concrete...

Thanks again

compression joints should rarely fail, but they should not be buried in concrete floors.

(they are also more expensive than soldered joints, in dry new work)

so probably an unskilled job.