Underfloor heating

[cdh]

I have laid a new concrete slab in newly extended kitchen. I have decided that I would now like to lay water underfloor heating.

The new concrete slab is 4 " thick set on to 100mm insulation & DPM. It looks like the underfloor heating should be layed onto the insulation, does any one know if it would be OK to lay directly onto the concrete and then screed over? I only have a maximum depth of 50mm to finish floor level.

Thanks

 

[Dan Robinson]

A nice piece of forward planning the dude.


In other words... you're screwed.

 

[Norcon]

I think his concrete slab is a sub floor which is laid over the insulation which seems to be the method used in england.
Here in NI the sub floor stays beneath the insulation in all circumstances.
But you're right though, he's "screwed".

 

[ALEC1]

if you use a compenstpated mixing vale it shoild be alright... the reason for the insukation under the pipes is to limit the thermal inertia of the slab....


most ufh controls have fixed flow temperatures, where as compensated controllers have variable flow temp which will elimiate over heating...

some low height buold up systems may work though...

 

[Dan Robinson]

He should have set the pipes into the screed.

If he had a further 18mm or so till finished surface, he could employ an overlay system, but with only 50mm there is not he can do practically .

Alec mate, can you send some of whatever it is you're smoking

 

[Agile]

Faced with that problem, I would pressurise the tube to 4 Bar when hot and lay the 50 mm of concrete
and reinforce with chicken wire and let it cure for at least a week and then warm up over three days!

Tony

 

[Dan Robinson]

So is the op going live with bare concrete floors?

Chicken wire is a dagt idea. Had to dig up and replace a sevtiom recently that had holed through chicken wire.

Why hot? As for pressure during testing....depends on the manufacturer.

Irrelevant here though. The slab is down. The op has 50mm to get ufh and finished floor fitted - judging from the first post anyway.

 

[Agile]

Pressure and heat is to expand pipe before concrete is laid.

 

[DP]

Pressure and heat is to expand pipe before concrete is laid.

Surely heat is the last thing one needs when pipes are screeded. As for pressurising, does the current 16mm pipe deflect much?

 

[ALEC1]

what the hell is wrong with a low height build up solution....some are only 22mm...

The thing that would worry me is that with out a variable flow temp the slab would get too hot...and the heating would not stop emitting heat....(hence the compensation VT valve)

if the final floor covering is wood... that might not matter