UFH possible leak

[trevorbayliss]

I have a leak in my system somewhere. I am trying to work out what the problem is. I dont think it is a boiler problem, but i cannot see any leaks anywhere in the house.

At the moment i am seeing if i still get a pressure drop on the house circuit, after isolating the kitchen UFH. If the pressure drop stops occurring it must be a problem with the UFH coil.

So my question:

How common is it for 15mm UFH to spring a leak. There are no joins in the concrete and it has all been working well for the last 5yrs. Has anyone seen a circuit in concrete suddenly develop a leak ?

 

[Richardthe3rd]

Here's my top tip, but keep it to yourself;
To find a leaking UFH pipe on a concrete floor, wet the cold floor with a mop, turn on the UFH. As the floor heats up you'll see the loops in the concrete - as the floor will dry out above the pipes first. Any leak will show up as a big blob of dry floor, as the water sprays out the pipe in the concrete.......👍😉

 

[James1991]

Is it a condensing boiler? The leak could be coming from the heat exchanger which would not be visible.
Have you checked the expansion vessel and the PRV?

 

[trevorbayliss]

yes it is a condenser - 7 y/o vaillant.

I have tested the exp vessel and pressure is ok with no water coming out when you test the valve. I have also tested the overflow pipe and it is bone dry.

What happens if it is the heat ex - where does the water go, does it evaporate ?

Thanks for info on finding UFH leak. I have isolated the UFH but the pressure is still going down so i am certain now that this is all ok (phew).

The boiler has lost 0.3 pressure in the last 2 days as i pressured up to 1.4, so the leak will take the pressure down to 0.5 in about 2 weeks. No water anywhere so i hope it is the heat exc.

Is this relevant ?

After 8 months of the instal the heat exchanger was changed due to noises. It was done under guarantee and that was exactly 6 yrs ago. Normally this is due to muck i think in the system, but it is very clean and i have a filter on the return pipe. Just thought i would mention it.