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View the thread, titled "Advice please - new wet underfloor heating not working as expected" which is posted in Central Heating Forum on UK Plumbers Forums.

A

AndySE

We would greatly appreciate some advice please. We've just had new wet underfloor heating installed to an upstairs shower room. The floor barely seems to be heating up at all, despite the pipes from the boiler feeling nice and warm. We think a polypipe system was used by the plumber, as pictured. Our concern is whether the overlying floor covering was done correctly as the heat would appear to have to transmit through wooden floorboards (pictured), plywood/tile backer boards, adhesive and then tiles. The adhesive/tile thickness alone is around 3cm. Does this sound correct for an upstairs floor please? Please see images below.
 
Here is the polypipe system, the wooden floorboards and the adhesive/tiles which sit on the floorboards

image.jpg


image.png


image.jpeg
 
It's controlled with a programmable room stat. It's a little bit warm now after around 12 hours. Not sure what is under the polypipe. Just remember seeing this red plastic going down and the pipes were laid on top. The quote just says to supply and fit underfloor heating and then cover with new floorboards.
 
Totally wrong as shaun said under floor heating never works well under a wooden floor should have used a overlay system and lay the tiles on top sorry to say cheers kop
 
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Might be worth checking flow and return temperature to and from manifold, mixing valve setting, flowmeter setting on manifold, air fully bled from circuit etc before condemning the UFH.
 
I'd say he's massively cocked up there if that's the system he's used, especially with laying floorboards over the top of it. It'll never work properly I'm afraid. Rip it up and start again
 
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Indeed it's wrong.
First floor UF systems should be properly designed and installed between joists with insulation under.
The only way you will get that working is to as mentioned check flow rates and temp and adjust as appropriate. Not going to be efficient though!
Or....rip it up and use overlay as suggested.
Hope you haven't paid the installer or whatever he is?
 
The above posts are right the red panels are for a screed floor not a suspended floor. The maximum thickness of timber above any UFH system is 22mm. I have attached a typical cross section. The overlay is ok but should only be used on top of a floor as the overlay panels are not structural. Thermal image of overlay is also attached.

Suspended floor with 400 Joists pipes @ 200 centres.jpg
 

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Advice please - new wet underfloor heating not working as expected
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AndySE,
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