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House renovation - Central heating system

  • 10-04-2022 11:46am
    Registered Users Posts: 1,036 ✭✭✭

    I have a family bungalow that ingrow up in. Central heating system is back boiler and oil combined.

    I want to up grade the system away from fossil fuel and have been advised to go electrical underfloor heating.

    The cost to do this will be high and I want to carry out as much work as I can. Obviously I won't be plumbing but could remove the floors and put I screen to lay pipes on.

    Is there guide line to the finish depth a floor should be and the level the screed should be at before pipes are laid.

    What to try and do as much labour myself.


  • Registered Users Posts: 757 ✭✭✭C. Eastwood


    Haven’t heard of underfloor electrical heating in many years. Anyone that had it installed many years old could not afford to switch it on.

  • Registered Users Posts: 1,036 ✭✭✭Hedgecutter

    sorry to clarify it a heat pump and underfloor heating.

  • Registered Users Posts: 757 ✭✭✭C. Eastwood


    Phew. That’s better.

    Do not have the new floor higher or lower than it is now

    I looked after the renovations of a 100 year old house recently where the client requested underfloor heating by an Air to Water heat pump

    Are you aware that the heating is on 24/7.

    It takes many hours for the floor to heat up and also to cool down

    My opinion is that the house should have an A rated BER Cert for this type of heating

    The underfloor heating Contractor wanted a 150 mm concrete floor to embed the heating pipes, which I refused to allow.

    Bear in mind that when you are working on an existing house- the Building Regulations (BR) most of the Regs state “as far as is practicable”.

    It is an existing house and the subfloor was very dry

    My Specification for the builder for the floor was:-

    1. 100 mm compacted hardcore
    2. fit radon sumps and pipes
    3. sand blinding over the hardcore
    4. fit a DPC. ( a radon barrier was not required in this area)
    5. 150 mm concrete sub-floor with A193 mesh up 40 mm in concrete. (concrete as dry as is possible).
    6. Allow time for the concrete to dry.
    7. 100 mm high density insulation with foil on both sides on top of the concrete.
    8. Sheet of polythene (DPM) on top of the insulation and up the walls 200 mm fixed to the walls ( this is to prevent the liquid screed from lifting the insulation and from pouring down the perimeter of the insulation). 40 mm vertical insulation up against the external walls outside the DPM. The DPM prevents this from lifting.
    9. underfloor heating pipes are fitted
    10. pour special 50 mm liquid screed.

    This above is very expensive.

    You could install an Air to Water heat pump with special radiators. The radiators will be on 24/7 and will be approx 21degrees C.

    Oil boiler rads heat to approx 70 degrees C when the heating is required.

  • Registered Users Posts: 1,036 ✭✭✭Hedgecutter

    Wow thanks for the level of detail. What concerns me is what i find when i start digging up the old floor. You laid radon pipes and DPC under all floors. Obviously, the DPC can’t cover the rising walls so it’s laid in each individual room with the edges to finish floor level?

    So i am looking at digging out 300mm deep from the current finished floor level? Is 150mm of subfloor necessary?