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Discuss Advice please - new wet underfloor heating not working as expected in the Plumbing Forum area at

  1. AndySE

    AndySE New Member

    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.
  2. AndySE

    AndySE New Member

    Here is the polypipe system, the wooden floorboards and the adhesive/tiles which sit on the floorboards



    • Creative Creative x 1
  3. ShaunCorbs

    ShaunCorbs S. Mod Trusted Plumber GSR Top Contributor!!

    Hope he didn't use what you have pictured

    As its totally the wrong system

    The one you have pictured is for a concrete screed system I think

    @Uheat – Wojtek@Uheat – Wojtek
  4. Chuck

    Chuck Active Member

    What was specified/described on the quotation/invoice?

    How's it controlled and how long are you allowing for the floot to warm up?

    What's under the 'polypipe'?
  5. AndySE

    AndySE New Member

    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.
  6. king of pipes

    king of pipes Trusted Plumber GSR

    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
    Last edited: May 18, 2017
  7. Vee

    Vee Plumber GSR

    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.
  8. muggles

    muggles Member

    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
    Last edited: May 21, 2017
  9. magicno1

    magicno1 GSR

    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! it up and use overlay as suggested.
    Hope you haven't paid the installer or whatever he is?
  10. StephenF

    StephenF New Member

    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

    Attached Files:

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