Underfloor heating question

[jamesc1459]

Hi,

We had our wet under floor heating installed in early July and air pressure tested to 5 bar (not sure why the plumber did it so high). Due to delays with our flooring contractor the wet underfloor heating system has not progressed any further and is still under air pressure. I've just noticed that it's dropped to 3.5 bar, though not sure when this happened. Our plumber is away for 4 weeks and not contactable at present. Is this an issue to be under air pressure for so long?

Is this slow decrease in air pressure an issue? Potentially as the weather has cooled down it has effected the pressure?

Any help is greatly appreciated. The system is a Novatherm Novapro (UK).

Thanks

 

[cross thread]

Temperature will effect the pressure .

 

[Madrab]

If the there has only been a 1.5bar drop in air pressure in the system in 7 odd weeks then I wouldn't worry. A lot can influence air pressure is a sealed system

I am surprised that he air tested it though, it's a notoriously risky thing to do as air can compress and fittings can blow off quite dramatically. Should really always be wet tested to 1.5time working pressure.

 

[Exedon]

As above should be filled with water then pressure tested.
Has the floor screed been done?

 

[jamesc1459]

Partially. One area is limestone tiles (completed) & the other area will be engineered wood flooring which is being installed W/C 8th September.

I asked the plumber at the time about the testing and he said air testing is fine.

 

[Madrab]

Partially. One area is limestone tiles (completed) & the other area will be engineered wood flooring which is being installed W/C 8th September.

I asked the plumber at the time about the testing and he said air testing is fine.

Well IMO he's wrong, as suggested, it's notoriously unpredictable.

Water is what it's to be filled with, so a test should always replicate what conditions it will be working under therefore water is what it should be tested with.

 

[Exedon]

I asked the plumber at the time about the testing and he said air testing is fine.
[/QUOTE]
I would seriously question his knowledge and competence.

 

[jamesc1459]

Should I be concerned that it has only been air tested, considering it has held pressure for weeks now.

 

[endecotp]

Should I be concerned that it has only been air tested, considering it has held pressure for weeks now.

IMO, no you shouldn't be concerned that it has "only" been air tested. The test result seems OK. The issue with air testing is that it's much more dangerous than testing with water. The idea of leaving the system pressurised with air for several weeks is ... scary!

 

[Madrab]

+1 - I wouldn't really be concerned either. I just wouldn't ever test something with air that wasn't designed to hold air under pressure.

In all my years I have just never come across a plumber that thinks it's ok to test a wet system with air and it certainly isn't an industry standard. 5 bar of air pressure does equate to ~2 bar water pressure so the as far as the actual pressure test is concerned then if it holds it holds. That and there is a standard of how to pressure test a wet system and it isn't with compressed air.