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https://www.askthetrades.co.uk/cgi-bin/yabb/YaBB.pl DIY Forum >> Plumbing Questions >> Pouring concrete over underfloor heating pipes https://www.askthetrades.co.uk/cgi-bin/yabb/YaBB.pl?num=1264683301 Message started by pryantcc on Jan 28^th, 2010, 12:55pm

Title: Pouring concrete over underfloor heating pipes
Post by pryantcc on Jan 28^th, 2010, 12:55pm

Hello all,
perhaps this should be in the building section??

Does anyone know if teh underfloor heating pipes should be filled with water before the floor is poured. Should they be pressurised?

I'm wondering about the pipes shrinking away from the concrete once they are brought into use as I guess this would interfere with the heat transfer?

Any ideas?

Thanks,
Paul.

Title: Re: Pouring concrete over underfloor heating pipes
Post by thescruff on Jan 28^th, 2010, 3:45pm

The underfloor pipes go under the screed above the insulation.

Yes they must be filled with water and under pressure when the screed is laid.

Title: Re: Pouring concrete over underfloor heating pipes
Post by CWatters on Jan 29^th, 2010, 8:44am

They should be pumped up and the pressure monitored for several days to ensure no leaks before pouring the screed. Pressure may change slightly due to temperature changes but not much.

We noted a slight pressure rise after the screed was poured - probably because of the heat given off by the setting process .

Title: Re: Pouring concrete over underfloor heating pipes
Post by Lectrician on Jan 29^th, 2010, 10:16pm

We worked on a site recently which was a small block of flats - only 4 story, 2 flats each floor.

The plumber was fitting UF heating with an electromax electric boiler (yup).

The plumber and builder laid the insulation slabs and UFH on top of the concrete slab / block and beam. The pipes where secured with with the push in clips which are meant to grab their own fixing in the insulation.

It looked a right mess, and most people on site commented.

They had arranged for a company to screed the floors due to access. The company where using a product I am not familar with which meant parking a truck outside and pumping a self levelling screed upto the flats. Shuttering was installed where required, and the screed poured. No troweling or leveling required. Just pour and walk away.

There was all kinds of problems with floating pipes AND FLOATING INSULATION boards!

Never seen anything like it! Men running around in wellies trying to push the pipes and board back under! Using anything and everything to keep it down! They had to do some work to repair areas afterwards where they weighted down the pipes/board with concrete blocks!

Not good!

Title: Re: Pouring concrete over underfloor heating pipes
Post by thescruff on Jan 30^th, 2010, 1:17am

If they had sealed the joints, so the liquid couldn't get under the sheets it would have been fine.

Title: Re: Pouring concrete over underfloor heating pipes
Post by CWatters on Jan 31^st, 2010, 10:19am

The insulation manufacturers also recommend a plastic sheet on top of the insulation before fitting the pipes to stop water from the screed getting into/under the insulation.

Title: Re: Pouring concrete over underfloor heating pipes
Post by Lectrician on Jan 31^st, 2010, 9:28pm

I have seen it done properly many times - but you had to see this mess to believe it!