UFH - fill before concrete?

[MarkH]

Morning,

 

Is it essential to fill the UFH pipes before the slab concrete is poured onto them? I've heard rumours to that effect but can't see why it's be necessary given they're only 50mm beneath the surface and seem more than rigid enough to take the slight pressure.

 

 

[jack]

Yes, I read that too - several weeks after our slab had already been poured!!!

 

I believe one of the major reasons this is done is to stop the pipes floating up when the slab is poured.  If they're tied down properly, this shouldn't be an issue.  So, "essential"?  Not necessarily.

 

Disclaimer: I know nothing.

[PeterW]

Yes for two very good reasons ..!!

 

1. To check for leaks before you encase them in concrete 

2. To monitor they don't get damaged or crushed during the pour. 

 

Fill and pressurize to a couple of bar and then watch and wait. When you pour, keep an eye on the pressures gauge so that you know if there is a problem. Post pour the pressure will rise as the curing concrete warms the water in the pipes so don't panic ..!

 

 

[Nickfromwales]

23 minutes ago, jack said:

Disclaimer: I know nothing.

I can vouch for him

13 minutes ago, PeterW said:

Yes for two very good reasons ..!!

 

1. To check for leaks before you encase them in concrete 

2. To monitor they don't get damaged or crushed during the pour. 

 

Fill and pressurize to a couple of bar and then watch and wait. When you pour, keep an eye on the pressures gauge so that you know if there is a problem. Post pour the pressure will rise as the curing concrete warms the water in the pipes so don't panic ..!

 

 

What @PeterW said. 

[jack]

Yes, should have been clearer.  The question was "is it essential?".  The strict answer is "no".

 

If the question is "should you do it?", then the answer is "yes".  I would have had a more relaxed time if I'd gotten around to doing it before the slab was poured.

 

As it happened, it was the follow-on trades that I should have worried about! 

 

Edited to add: So what do you do as, say, the third of four lined-up concrete trucks starts dumping its load into your slab and you suddenly note a drop in pressure?  What could realistically you do at this point?  Stop the pour?  Start digging around in the stuff already poured to look for the leak?  Genuine question - sounds like a very unpleasant position to be in!