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Under Floor Heating Help

Discussion in 'Plumbing and Central Heating' started by richo100, 16 Mar 2021.

  1. richo100

    richo100

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    Hi

    We will be planning a large renovation project on our house in the next 3/4 months. Everywhere will be back to brick with extension etc..
    I’m guessing all the subfloors are concrete and the new extension will be concrete base. We are having tiles so wanted the water UFH heating to heat the downstairs. Was is best way to install this? I have been looking and would we have to lay insulation boards and then pipes and then screed over the top? How much does this add to finished floor height?

    Is there a way to scribe channels in the concrete to slot the pipes into so it wouldn’t add any additional height?

    Can this run off a combi boiler? Same boiler heats UFH ( ground floor) and then rads other floors?

    I might be way off the mark here but what is the best way to do this?

    Or the other option was to have traditional radiators but then just electric UFH to take the chill off the floor.

    All advice greatly appreciated?
     
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  3. dilalio

    dilalio

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    Best way is insulation then lay pipes then screed @70mm on top. This usually means breaking out existing solid floors and starting over. Suspended floors can be converted to solid.

    There are thin profile systems available that are laid over existing solid floors with back backer boards containing grooves.

    There are concrete routing (grooving) services available.

    Yes, you can run it from a combi, KW load/input permitting.
     
  4. muggles

    muggles

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    JK Floorheating can rout out your existing screed but it'll be more expensive than having a builder dig it all up and start from scratch
     
  5. WiltshireWarrior

    WiltshireWarrior

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    I used 20mm high blue insulated panels that had precut grooves for the pipe (I used a mix of 12mm and 16mm) and then covered with self levelling (SF or wickes etc) and then either tiles or wood glued down

    this allows me to add the absolute minimum height to my floors, without cutting the concrete subfloor

    the blue foam panels (ebay) are fixed to concrete using thinset tile adhesive.
     
  6. ericmark

    ericmark

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    I had electric fitted, waste of money, the first thing was floor was dug out and polystyrene blocks fitted, then plywood, then heating mat and then tiles. The result was even with heating off the floor felt reasonably warm, so it was the insulation that made the difference not the heating.

    The heating did work, it was in a wet room, and idea was to dry the floor, but once cooled with shower, it too ½ hour for the tiles to get even slightest warm, so the heating needed to go on 1½ hours before using the room to even feel a warm floor, and around 4 hours to warm the room, and the heat from tiles was less than the extractor fan would blow out, so wet room without towel rail on was same temperature as hall where the replacement air came from. Lucky also had a towel rail or room would have been too cold.

    In the main under floor heating is limited to 27°C, where a radiator is more like 70°C, OK bigger area, but the whole idea today is down to speed. To maintain all rooms at say 20°C 24/7 is considered as a waste, when most rooms only used for maybe 6 hours per day, so as soon as you decide to allow a room to cool, efficiency is down to reheat time.

    So if a room is used for 3 hours and it takes an hour to heat, 75% efficiency, not quite that simple, but I am sure you can see the point, so the faster you can heat the room the more efficient it is, however this needs balancing against cost, but a Myson iVector fan assisted radiator is likely the fastest water heated method to heat a room, and with any fan assisted because it moves the air it can be directed onto to floor, so you can have a warm floor, and also same unit can also be used for cooling, there is some noise from the fan, but the new units have 5 speed fans and output is controlled by fan speed, so most of the time you can't hear the fan. But once you look as cost, you can see the disadvantage as well, but under floor heating not cheap.

    There is no perfect heating system, and much depends on the home, with mothers house the sun in bay windows was a problem, so speed of reaction to outside conditions was very important, so we used electronic TRV heads so it could turn off heating faster when sun came out, but our house was open plan, and speed of cooling not so important, it was only heating speed, and with a standard radiator and Myson fan assisted plus a gas fire we had around 9 kW of heating in living room, so no need for any geofencing simply turned it on when we got home.

    Two years ago I moved, oil central heating now, whole boiler only 18 kW, so use stage heating, kitchen then dinning room then living room etc. Again using electronic TRV heads.

    Son used the return from radiators, so water cooled by radiator first then it heated floor, this allowed the return water to boiler to be cooler so better latent heat extraction, and the TRV also controlled floor temperature, UFH on the cheap, but my brother-in-law has the normal method of a second pump, and the water in the under floor heating is circulated by second pump, and as water cools more hot is added, but installation cost was far higher.

    We call the people who install it all heating and ventilation engineers, an engineer is basic some one who has trained to above level 3, normally level 5 or 6, where a fitter is normally trained to level 3 at best, over level 3 is higher education i.e. University, and my point is the skill required to design an efficient system is high, as an electrician not even a plumber I can put in a system that works, but that does not mean it works efficiently, and there is a balance, if we consider the system has a life of around 10 to 15 years, then any saving needs to be realised within that time, so at say £500 per year heating bill, a 10% saving needs to cost less than £500 to be worth while for economy, clearly comfort is another story.

    But when I was house hunting I rejected any house with under floor heating unless they could show insulation was laid first, as it can work out expensive heating the ground below your house, so we would be greeted with a proud owner showing off their UFH but it was that which put us off buying.
     
  7. WiltshireWarrior

    WiltshireWarrior

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    I’ve completely redone my entire house and more than doubled the size of it. After years of playing around with endless rads (I had 28. I’m lucky enough to have a very large detached 6 bed house, though I did build most of it!) I decided this time I’d install all ufh. Up and down stairs!

    I had one bad experience along the way with electric in one room due to floor height restrictions but that got replaced. Leccy is too expensive to heat a largish floor. Ok for an en-suite (though obviously not for you)

    and two years later it’s great. I over insulated under wherever I can and also spent time insulating walls and the loft. All controlled by my iPhone (EvoHome)

    result is a lovely even heating. Takes maybe an hour to come up to say 22 normally so comes on at 6am and we usually get up at 7am

    and no annoying radiators to get in the way of furniture or to dust or to bleed or ....

    just my opinion. I’m NOT arguing ufh is “perfect”
     
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