Pressurising an UFH system before applying a flow screed….why

[aspley]

Hi Guys, just about to apply a flow screed directly on top of the UFH pipe work and cannot understand why the system needs to be over pressurised before the screed is layers
Any ideas why this is necessary ??
Cheers

 

[denso13]

Any ideas why this is necessary ??

So any leak caused by screeding will show up immediately.

 

[jackthom]

I’ve no experience of this but a quick Google gives the following

https://www.johnguest.com/speedfit/blog/common-underfloor-heating-mistakes-during-installation/

 

[Exedon]

Very common mistake not to pressureise pipework must be with water to expand pipe air test no good needs to remain pressurised until screed set.
You also have no warrant if not pressurized.

 

[aspley]

Thanks guys. What I couldn’t grasp was that by pressuring up to 6bar that pressure expands the pipe…..It must only expand by a fraction of a millimetre but apparently that is what is required before the screed is applied. So I will do as it says