UFH manifold losing pressure

[Moonshine]

More UFH woes, after my ufh issues i went round the other manifolds that were installed under screeds in august, and have found the main one reading no pressure.

 

When it was installed it was at 4.8 bar, and after a few days had dropped to 4.2 bar. I flagged it with the plumber that said it was fine and unless there is water visible the pressure can fluctuate with temperature, and it was left at that as i couldn't see any water.

 

There is another manifold what was installed at the same time (basement) and is sitting at 1.5 bar, this was originally installed with pressure about 2.4 bar.

 

is loosing all pressure over a couple of months normal? the other manifold i have seems to imply not

[crispy_wafer]

Temperature fluctuations, would be my assumption, but run your fingers around the manifold at pipe entry points, bleed points etc, for any sign of moisture?

[joe90]

I tend to run mine at about 1.5 bar (cold) but it does go up with temp, in fact if I up the pressure the ASHP tends to trip out with “over pressure”.

[Moonshine]

56 minutes ago, crispy_wafer said:

Temperature fluctuations, would be my assumption, but run your fingers around the manifold at pipe entry points, bleed points etc, for any sign of moisture?

The thing is that these aren't connected to a heat source, its laterally the manifold and only the UFH pipes in the screed.

 

So the only temperature fluctuation i can see is happening it the temp of the water when used in august and it getting colder till now.

 

This is evident on the manifold / UFH in the basement dropping from 2.4 bar to 1.5 bar, however its must be a lot of contraction from the water in the pipes for the pressure at the ground floor manifold to go down to zero bar from 4.2.

 

That said the length of pipes a ground floor are very long so any contraction may result in a big pressure drop.

 

The this still no evidence of water leaking from above with what i would expect wet spots in the screed (there is a DPM below insulation, and a vapour barrier below the screed), no water or remanence of water in the manifold cabinet 🤔 

Edited October 28, 2022 by Moonshine

[Moonshine]

Went for an evening check on site after heavy rain. Roof all watertight phew.

However in one corner of the house in the torch light the screed looks darker than the rest.

Could this indicate a water leak in the underfloor heating pipes over such a wide area, and loss of pressure?

The camera flash does empthises the difference

 

Edited October 31, 2022 by Moonshine

[Olf]

On 31/10/2022 at 21:13, Moonshine said:

Could this indicate a water leak in the underfloor heating pipes over such a wide area

For sure water got there somehow

If there is a point leak in the slan, the moisture will seep through the conrete, thought it would do this radially from the point of the leak (just pour a bit of water elswhere to see what's happening). Saying that, edges of the slab could promote moisture migration and make it hard to say what exactly is happening there.

 

[Andehh]

Damaging UFH pipe is rare, it's very durable and resistant to abuse. Any reason why it could be damaged? Bricks dropped on it, heavy metal work, revenge/spite? 

 

[Mr Punter]

Has anyone (like plumbers) been working on site.  They may have leaked some water and not told you?  There is what looks like a length of pipe dangling down.  Plumbers are to blame for most things.

[Temp]

Get/do a pressure test. Pump it up to 3 bar. Leave for a few hours then repressure to 3 bar again, wait a few hours and check the pressure again. It shouldn't change during that second spell unless there is a significant change in temperature or a leak. It might change in the first spell if it's not been pumped up for awhile.

 

You can either use the mains to pressure it or the kit is £30-40 on Amazon.