Underfloor Heating using Electricity

scammal

Hi. Has anybody out there any direct experience of a heating system where an electrical element is put directly into the floor slab of a new house to produce a heated floor? I'm looking at it as part of a passive package. The timber frame company are making one claim about its power usage(even accounting for running it off a night meter), any plumbers i spoke to are saying "run a mile"....i would like to hear from someone who lives in a house with this system, and how much is it costing them to run..relative to how well insulated their house is / how much heat the house is calling for..thanks

Effects

Did they give you specs on the power demands of the system? I've never seen anyone use it for more than a bathroom with a devi mat. What's the advantage over regular under floor heating? Install cost sounds like the only one perhaps.

rebelfff

It'll probably cost a fortune to run, especially if it's heating a large area. I'd avoid electric heating.

Mothman

Electric underfloor installed in my house when built 15 years ago.

126sqm. Single story. 2 cables installed, 2.5kw in south half and 3kw in north half. I got 2 spare cables installed for £75 a piece in case of damage. A standard immersion timer can operate them. So really cheap install. I went mad and spent about £500 installing an auto system that measured outside temp and floor temp and regulated how long the cables were on. it worked really well! but could have managed quite well with timer.

My house is no where near passive standard, but is low energy with triple glazed and well installed insulation. We really only used the under floor heating for first winter because we have plenty timber and installed a wood burning stove after that. For that winter we only used the 2.5kw cable, only with night rate and the electricity usage was about £10 extra a month. I think night rate was about 3p a unit then, so about 11 units a night or cable on 4 to 5 hours a night. No idea what the winter was like, but winters were generally milder then than they have been past few winters. But even in the really cold spell a couple winters ago, a constant 2 kw is enough to heat house and that is now with upstairs converted. A passive house should have less of a demand.

My reasoning is why spend so much in creating a low heat demand and then spend loads on a system to supply this low demand. For me the cables worked well and even now after energy inflation I think still wouldn't be a huge cost though we only use wood now.

scammal

Thank you all for your replies.
much appreciated.

Parichards

There is a lot of nonsense spoken particularly by plumbers when it comes to electric underfloor heating. You have to remember that with this system there are no pipes and no movement of fluids which is of course what plumbers are interested in. Electric underfloor heating is maintenance free and doesn't leak so it's of no interest to plumbers.
There are a couple of different methods of delivering this, you can use the traditional Devi type mats as mentioned above, these are elements enclosed in a mesh mat that then go below your tiles, wooden floor. Then there is the printed polymer sheet, this is extremely effective only a few microns thick easily applied and guaranteed for 25 years, there is zero maintenance.
If you are really interested in this it is probably best to ally it with other efficient water and living space heating systems. Check out Hotfoot in Kilcoole Co Wicklow, hotfoot.ie they have an excellent offer in this area some very interesting testimonials on their website and will give you some honest and credible information on this whole area.

Markcheese

Realistically if your house is built to passive standards it won't take a lot of energy to heat it ... Are you putting in a stove as well ? If so will you need underfloor heating throughout ?(bathroom might be nice)
Also will it even be worth your while putting in a night rate meter ? Depends on how many in the house and your lifestyle ? ..
Always thought it'd be worth matching a wind turbine to electric underfloor heating and water heating ! Might depend where you live though and probably wouldn't pay in the short term .

Bricriu

I had underfloor electric-cable heating installed as part of a Scandinavian build, and am very happy with it.

I have 3 circuits: one for downstairs bathroom, which I use on a timer during the winter, one for upstairs bathroom (which I have never used, as it was not needed) and the other (the largest circuit) for all of the downstairs area (excluding downstairs bathroom). I rarely use the circuit for all of the downstairs area, as a stand-alone wooden stove heats the house very well (as well as the Solar-gain from the windows).

The times I have used the heating for all of the downstairs area were when I ran out of wood or when I was too lazy to put on a fire. It takes a while for the heat to generate up from the floor, but it is very comfortable when it does. It's handy to have some back-up (in addition to the stove), and from dealing with the company, I trust their low electricity-usage figures completely.

fclauson

Markcheese wrote: »

Realistically if your house is built to passive standards it won't take a lot of energy to heat it ... Are you putting in a stove as well ? If so will you need underfloor heating throughout ?(bathroom might be nice)
Also will it even be worth your while putting in a night rate meter ? Depends on how many in the house and your lifestyle ? ..
Always thought it'd be worth matching a wind turbine to electric underfloor heating and water heating ! Might depend where you live though and probably wouldn't pay in the short term .

this is a complete missappreciation of what passive is

Passive house need heating !!!!!! - but just a little of it and it needs to be evenly spread.

Heating via the MRHV has challenges (the air is moving so slowly) and depending on your layout/orientation etc may well not be enough in reality (our back bedroom gets very little sun for example - hence little solar gain) .

to use my favourite analogy - you cannot heat a fish pie putting a Bunsen burner at one corner.

I have UFU with a HP - it uses around 1 to 5Kwh of electric each night during the heating season - across the whole floor - with the HP and Outside temp compensator working out how much to add

cavatina

fclausion,
can I ask what the output power rating of your heat pump is?

fclauson

Its an 8Kw HP - 2Kw are HP and 6 are immersion (which has never been on in 12 months)

420% rating for heating - about half that for h.w - but I have not measured what I am actually achieving

psychhead

are these electric systems compatable to run with a back boiler stove? Was looking into a heatpump but have been warned away from it.

fclauson

what's you over all config - and how well insulated is your house

scammal

I should take myself off this post as I eventually went with a 9kw panasonic t-cap air to water heat pump into piped underfloor heating @ traditional 150mm centres. 300l solar tank ( long coil) ..sustainable job...didn't trust the electric underfloor, a lot of the timber frame companies seem to be pushing it...