How good is underfloor heating in a large room

[HappyHippyDad]

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.

 

[pc1966]

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.

 

[Mike Johnson]

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. ???

 

[Zerax]

I live in an area where I want to know what that car was doing driving past my house.

Probably 'casing the joint' !

 

[Mike Johnson]

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.

 

[marcuswareham]

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

 

[brianmoooore]

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.

 

[Mike Johnson]

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.

 

[BeeDee]

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.

Per day... ouch!

Thanks for this, the bit I was missing in the maths was the W/m2.

 

[andyb]

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.