25 Jan 2011
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United Kingdom

We are refurbing the family home, a 3 bed bungalow. New Kitchen, family bathroom and 1 enuites and new 4th bedroom.

We maybe planning on having Light Cream highly polished factory sealed porcelain 600 x 600 tiles installed in our new open plan kitchen with Devimat underfloor heating on top of a conctere floor. Approx area (17 sqm).

We were planning on having this in the loung and living room area (48sqm), and 2 ensuites and 1 family bathroom (17 sqm). Again concrete floors all round.

But would the cost of having all of the the above (82sqm) in the same underfloor heating be too expensive to run?

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It would depend on how it was installed, if you slap the mat straight on the concrete then you have to heat the slab which with a little wire heating system could take a month, you need to have the whole area perfectly flat and then install insulation boards onto the slab, lay the cable and preferabally bury it in self leveller and then tile over top, that would boost warm up time dramatically, shurely a pumped UFH system from the boiler would be a better solution, do you want this for primary heating or to just take the chill off of the tiles?

This would be to take chill of tiles.

We were considering wet UFH but as all the flooring is concrete, the cost of hacking out concrete and then installing would be too expensive.

If you only want to warm the tiles to a little over room temperature then there will not be a lot of heat lost to the air, so it would seem prudent to insulate under the tiles (between the concrete and the heating mat) as best you can afford and, of course, within floor height constraints. This should minimise running costs as once the floor is up to temperature, the thermostat will only have to kick in every once in a while to maintain the set floor temperature level.

The exact running costs are anyone's guess, as it will vary from system to system depending on how much time the heating is having to remain turned on in order to maintain your setpoint!

Oh, and you don't have to "hack out concrete" for wet UFH. If you can handle an inch or two increase in floor height then all you need is to lay a new screed over the heating pipes.
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It varies on who I talk to re: Wet UFH.

What would be the minimum set up requirements for WET UFH for a concrete floor.

Insulation thickness, Pipe thickness?, Screed thickness?

On top of this would be laid tile adhesive and 10-12mm porcelain flooring and 15mm engineered wood flooring.
Insulation depends on what you decide to lay - Marmox boards, for example, are available down to 6mm I believe, although the thicker the boards, the greater the insulating properties. The pipe is likely to add another 15mm, more if you use a former to hold the pipe. Add at least 35mm on top of that again for the screed.
Insulation thickness,
The same as it would be for electric heating, and it's by far and away the largest component of the overall thickness.

Pipe thickness?,
Thicker than electric cables. Can you get microbore UFH?

Screed thickness?
The same as for electric? I don't know.

Cautionary tale.

On top of this would be laid tile adhesive and 10-12mm porcelain flooring and 15mm engineered wood flooring.
So that's the same as electric.

This would be to take chill of tiles.
So why put it under wood? Wood is not chilly.

But this is a better, much cheaper and much more environmentally sound way to take the chill off of tiles.

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