Discuss How good is underfloor heating in a large room in the Electric Underfloor Heating Wiring area at ElectriciansForums.net

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BeeDee

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Morning all,

I'm about to embark on some home renovation and the kitchen is the first target. We are looking at making it bigger, all in the room would be 32m2. I have read that electric underfloor heating systems are better and more efficient for smaller rooms, but that they can take a while to heat the room and are more expensive to run than wet underfloor heating systems. I'd prefer electric however, ideally throughout the house as I'd like to get away from gas entirely and move towards renewables.

So my question is, how practical is it to have electric underfloor heating in a room of this size? Could it be the sole heating source in the room (bare in mind just last week we had temperatures of -10C)? And would it be prohibitively expensive to run (I realise this is subjective but given it's one room in the house I'd hope it would be no more than a £5-£10 a month in running costs)?

Thanks,
 
For an open room like that you are looking at 100 to 200w per sq m
Therefore 3 to 6kw

At 15p per kwh
This is roughly
45 to 90 pence per hour.

I think £5 to £10 is a realistic cost to run PER DAY during the winter.
 
I would imagine a ground or air source heat pump would be your best long-term option as you don't need (or want!) too hot a floor and the running costs would be much lower (by 2-3 times) than normal electric heating.

However, the installation cost of that would need consideration, and any practical issues of where it can be located.
 
This is the problem when people want to go 'eco' and use renewables. But then end up using 6 kilowatts of power just to heat the kitchen!

No offence intended to the OP.
 
Hi - it’s good to think this through before you build. So well done :) .
If you do choose to go electric underfloor heating can it can work very well. It has very few moving parts and it is easy to install. But, if the mat gets damaged it just stops working. This can happen during tiling and it can be quite difficult to fix, ie tiles up. Meanwhile you’ve no heating. So perhaps make sure the responsibility to install and commission is clearly linked to ‘significant’ payments.

It takes power to increase the room temperature and the more insulation you have the less power is required. So perhaps spend more on this aspect :) .

Unless you generate your own power, gas is going to be the cheapest per kW but that too may change in future.
 
Wet underfloor heating can be accommodated with an electric boiler if you are dead against gas, essential to insulate under the floor to ensure heat always goes where you want it and as above don't heat under the units or fixed furniture, but I am sure you have identified that in your research.
 
I would imagine a ground or air source heat pump would be your best long-term option as you don't need (or want!) too hot a floor and the running costs would be much lower (by 2-3 times) than normal electric heating.

However, the installation cost of that would need consideration, and any practical issues of where it can be located.
And the noise from the external compressor can be considerable if you live in a Rural environment, mine are very noticeable if you are near them.
 
I put 160w P/sqM electric underfloor heating in my 12m2 conservatory. It is absolutely wonderful! I walk in, in the morning in my bare feet and it just feels lovely ?. It stays on all day in the winter keeping my feet lovely and warm. It also costs a bloody fortune!!!!! I wish I'd bought a pair of slippers!

It is lovely, but it feels extravagant and is very expensive to run. My electric bill is usually around £40 p/month and it went up to around £130. The install was done properly with good insulation below. Also, it's not just the winter months you use it. The tiles are cold throughout spring and autumn so it is used (albeit less) in those months too.

I don't know much about wet underfloor heating, but if I had the choice I would go with that, as I assume it is far less to run. I'm sure it most be quite a bit more to install, but I bet you make that back over a few years with the reduced running costs.
 
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With regards being a primary heating source, the answer is 'yes', it can be a primary heating source. However, you would need the correct heating mat/coil for that. You would also need all the correct underfloor insulation. You would also need to have the house very well insulated. Without all of these things it will not be a very warm house in the middle of winter.

In this cold spell we have just had, my conservatory (bear in mind lots of windows and pvc roof) could reach about 17 degrees(C) with the underfloor heating on constantly throughout the day.
 
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And the noise from the external compressor can be considerable if you live in a Rural environment, mine are very noticeable if you are near them.
The one place I have actually stayed at that featured an air-source heat pump and under floor heating was one of the Landmark Trust properties up north (The Shore Cottages No 2) and it made it a very comfortable stay, nothing like the freezing cottage it would have once been had you not got a big fire on.

In that case they have an out building and the external compressors/heat exchangers were behind it and really not noticeable at all inside the property, though of course there was also the sea noise to mask it.
 
As I said it all accords on the ambient noise level, if you live in town with constant traffic passing by you probably will not hear it at all, I live in an area where I want to know what that car was doing driving past my house. ???
 
Funny you should say that my nearest neighbour had their camper van stolen over night just recently, they drove it through my paddock and out of the gates at the other end so not passing either hose at close quarters.
 
I have electric underfloor heating in my consventory and bathroom, Both I installed using the heating element wire on a roll rather than matts, but i believe the matts are the same thing just the wire is already nicely spaced for you

The underfloor heating in my bathroom works very well, although the bathroom is a very small room and also upstairs (timber ceiling)

The consventory on the other hand is not so good, I think the reason for this is that underneath the heating wire is concrete floor. I think I am losing heat into the concrete and in hindsight I should have done something to insulate below the element so all of the heat will be going upwards into the slate tiles and into the room rather then heating up some concrete, so might be worth thinking about or looking into insulation etc

The consventory is about 3m x 2.5m and although the floor gets warm so is nicer to walk on, it does little to heat the room

The bathroom can be heated of the underfloor heating, and if you put the thermostat right up the floor can be almost to hot to walk on (something that can never be achieved in the consventory)

I also put in backup heating wire, which is not connected but can be if the main heating wire fails, or got damaged when I was tiling
 
The consventory on the other hand is not so good, I think the reason for this is that underneath the heating wire is concrete floor. I think I am losing heat into the concrete and in hindsight I should have done something to insulate below the element so all of the heat will be going upwards into the slate tiles and into the room rather then heating up some concrete, so might be worth thinking about or looking into insulation etc

The consventory is about 3m x 2.5m and although the floor gets warm so is nicer to walk on, it does little to heat the room
You are attempting to heat planet Earth, so it's never going to work properly. You need to have at least 75mm of Celotex underneath the screed, preferably more.
Like an electric shower, electric underfloor heating is always going to be a poor substitute for those powered by hot water.
 
It's always difficult to retro fit underfloor heating due to the depth required for efficient insulation, most of us do not have the luxury (if you can call it that) of designing our houses from the ground up, so floor levels can be taken into account, but even 12mm of insulation is better than none, with the heating mat any leveling screed adhesive and tiles or engineered wooden flooring we are talking about increasing the floor height by at least 25mm, this can cause all sorts of problems at the threshold to the next room, unfortunately wet UFH would increase this height even more, so unless you have nice high ceilings and intend to raise the floor over the whole ground and first floor (not many of us have more floors) UFH is not a viable solution, but it is nice and wet UFH is cheaper to run than most any other form of heating not matter what the fuel.
 
Per day... ouch!

Thanks for this, the bit I was missing in the maths was the W/m2.
It's not as simple as working out the full load then multiplying this by the hours that you have it on. As already mentioned previously in this thread by others, a massive factor is insulation. A 200w/m mat will take more power than a 100w/m mat, obviously, but it will heat faster and bring the room to temperature sooner. After that it's down to insulation, if it's poor it will be on most of the time but a well insulated room and floor will require a lot less power to maintain the temperature.
 

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