underfloor heating - anyone advise?

[tracyk]

My mum has a normal gas radiator system in her house and wants to replace 2 rads in her lounge/dining room to maximise wall space and update look. Space is still limited - and I thought of UFI.
Any experiences?
Would it link into the exisitng central heating or be independent?

My dh wants this for our house. As I understand it, it links to the existing system as dh is trying to persuade me we could have it done room by room or only in certain rooms.

I'm in the middle of investigating this for an extension on our house, so I have a basic understanding.

There are two types: wet and dry. Wet is hot water run through pipes under the floor and linked into your boiler. Dry is electric cabling, either laid as a cable or in a sort of mat that you can lay under the floor. You can certainly have it fitted in some rooms only - that's what we're planning to do.

What sort of floor (structure and finish) does your mum have? It works best under solid floors with hard (stone, tile) finishes although you will still get heat through a carpet.

We had underfloor heating in our old flat, electric cabling that was laid under a concrete floor. With no other form of heating it was very inefficient, the flat always felt cold, and our heating bills were enormous - the last winter electricity bill we had there was over £500 for the quarter and that was mainly on heating.

I think she will want a carpet on top. Its a 1970's built house - so I think it's just hardboard underneath her existing carpet.

We have UFH in our bathroom and a radiator!!
The UFH is great for the cooler spring/autumn nights when we dont need the CH on.
We have the electric wires and its set on a thermostate...bill hasnt been excessive but thats probably because we only use it for 4 months of the year...nice on the toes though when you step out of the shower!!
We have pipes from our boiler running under the floor and the spots where they are are lovely and warm...maybe the boiler type would be better.

I don't know enough yet to make a guess about the relative amounts of heat each type of system chucks out - the wet systems seem to have water going through at about 40 C (neutral room temp is about 20-22 C but radiators chuck out a lot more heat - up to 80 C, I think) whereas the electric systems are quoting output of 100 watts per sq m. Hmmmm, how I am supposed to compare like with like there then?

Anyway, my instinct is that the wet system sounds more reliably warm. Bear in mind carpet is fairly insulating, so you won't feel the benefit of UFH as much as you would on stone, and will probably need to keep the thermostat a notch or two higher.

To fit, the whole floor comes up, then a layer of insulation is put down(to stop the UFH heating the floor beneath it), then the pipes and supporting materials, then a layer of hardboard on top before the carpet. Quite disruptive and will add about 15 - 25mm to floor heights (think about how you deal with doors opening in etc).

You'll need to look at your boiler capacity to make sure it is up to the job (combination or condensing boilers are best for UFH).

Best to get a quote from a reputable company, really, they can tell you the wrinkles. I've got some names at home, so if you can wait until tomorrow, then I'll put the links up.

thanks Gizmo - also one of the editions of Homebuilding & Revoating mag has a no nonsense article on UFI and they types of lifestyles that would benefit from UFI - eg at home all day constant heat and working all day and requiring quick heat up times etc. Can't remember which was good and which wasn't - so will have to dig through and find it.