PRV replaced on combi, pressure still dropping - what next?

[moorfield]

I've recently had some problems with system pressure regularly dropping on my combi (Ariston Microgenus) typically from 1 down to 0.2 bar over 2 days. Our plumber has replaced the PRV on it but the problem persists.

Boiler is connected to a UFH manifold. The manifold has its own PRV which does not appear to be dumping water (I have containers outside underneath both PRV pipes). And I'm 99.9% sure there are no leaks or signs of water in/around the manifold.

So any ideas what I can check next?

All I can think at the moment is to run each of our 4 UFH zones separately to compare if (god help us) the pressure drop only happens when the most commonly used zone is on.

What about the boiler, eg expansion vessel - any obvious signs or tests I can do to check?

 

[bengasman]

EV is the first thing to check with leaking prv; the chap has either already done that, or is a complete muppet.

 

[islandman]

We had similar with a drop of about .1 to .2 bar per day.

Turned out to be a minute leak in the pipework under the kitchen units -- fortunately we located it fairly easily and it was easily accessible. Why this leak started is anyone guess but it did.

It really was only a minute leak and it surprised me how as such it would drop the pressure so quickly. When repressurising it seemed like loads of water was going in. I guess it's amazing how much you can lose over 24 hours.

Had it fixed 2 weeks ago & so far pressure is rock solid.

 

[moorfield]

Turned out to be a minute leak in the pipework under the kitchen units -- fortunately we located it fairly easily and it was easily accessible.

Well we have UFH tubes (Kee triple tube) running under tiled floors so not easily accessible

So my thinking is if I run each of our 4 UFH zones individually for a few days each then either
(i) if the pressure drop occurs in one of them not others it might be a pointer that one of the tubes is knackered in that zone - god knows where the leak would be or the water would be going if that is the case
or
(ii) if the pressure drop occurs regardless of which zone is on then its back to the boiler.... (or leaks from tubes in all zones - unlikely I would hope).

As mentioned looks like no leaks on the manifold or tube connections.

 

[Agile]

Why post the same question on different forums when the same experts visit most of them?

See my reply on another site! Or do you expect me to copy and post it here? Better still YOU could copy and post it here!

Tony

 

[moorfield]

Why post the same question on different forums when the same experts visit most of them?

See my reply on another site! Or do you expect me to copy and post it here? Better still YOU could copy and post it here!

Tony

Not everyone visits both!

I don't have a problem with cross-posting links
and continuing the discussion on only one - which one is "better" ?

 

[Agile]

There is no one forum that is "best".

The advice given depends mostly on the amount of information given by the OP and then on the ability of the engineer to asimilate that often limited information.

As tests are not possible and the information given is often limited than any internet reply will be a considered guess.

The only sure way to diagnose a boiler fault is to be in front of it.

I went to one yesterday where a heating engineer had spent 45 minutes and still had no idea what was wrong. All he or the owner would have needed to have done was to notice that the selector switch was jammed.

Tony