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Discuss Help with RetroFit UFH in the Underfloor Heating Forum area at

  1. engineer21

    engineer21 New Member

    Hi, first time poster here so be gentle!

    Background, im not a plumber but very competent DIYer a ships engineer which basically means i do plumbing and boilers on a rather large scale! so i have decent know how.
    But i also know my limits as well.

    So basically we have bought a 4 bed bungalow which currently has electric storage heaters (we haven't moved in yet but they are *****)
    Ideal thing is to retrofit the house with UFH.
    Now we are just starting with the renovation, new kitchen, flooring etc
    I have access to the full underneath of the house from a basement, although its not full height i can get everywhere, and there are lights etc there, the under floor is not insulated yet

    the debate im having with myself is do i go Overlay UFH or fit from below with aluminum plate like the Clippa Plate from Nu-Heat, this means no height buildup and i can do it at my leisure (for want of a better way to put it)

    has anyone installed UFH from below and how has it worked out??

    also due to funds i may do the main living spaces with it now and fit rads in bedrooms until i do everything later does this seem silly or like an ok idea?

    most likely going for an oil fired boiler (no mains gas etc) or possibly air source heat pump but my knowledge of these are limited and would have a plumber install either and commission the whole system

    house is not bad for insulation and id be insulating under the floor anyway regardless of UFH or not

    anyway thanks in advance for any advice

  2. ShaunCorbs

    ShaunCorbs S. Mod Trusted Plumber GSR Top Contributor!!

    Overlay system

    Remove all the flooring
    Install ply in between the joists so you don't increase your overalll height that much
    And insulation on the underside of the ply to save wasted heat
    Then fit your ufh overboards and sort your flooring out etc

    It's best to do the whole job in one and not piece by piece
  3. engineer21

    engineer21 New Member

    Hi thanks for reply,
    I don't think it would be possible to remove 200m2 of chipboard when I have full access underneath it?
    What's wrong with installing from below??
    Alu plate, ufh pipe, 100mm glass wool and 50mm kingspan then support wood.

    Was hoping to space the pipes at 150mm

  4. ShaunCorbs

    ShaunCorbs S. Mod Trusted Plumber GSR Top Contributor!!

    It's not the best heat dissipation and your heat times will suffer
  5. engineer21

    engineer21 New Member

    Ok yeah that is a concern of mine. So the overlay build up of 15mm system would give a much better heat output to room or just quicker warm up?

    Then I'd have to skin the bedrooms I was just putting rads in to level up the floors

  6. ShaunCorbs

    ShaunCorbs S. Mod Trusted Plumber GSR Top Contributor!!

    Yes as there's not much on top
  7. engineer21

    engineer21 New Member

    so if i go with an overlay with min build up, can i route the pipes two and from each zone under the sub floor, just well insulated?
  8. ShaunCorbs

    ShaunCorbs S. Mod Trusted Plumber GSR Top Contributor!!

    You can airing will take slightly longer but nothing negative about doing that
  9. engineer21

    engineer21 New Member

    Ok thanks for that, think maybe overlay will work better, engineered wood flooring over the top and i will still insulate below the chipboard floor.
    Any other tips? or the best systems if you have any recomendations
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