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Electric Underfloor Heating

(10 Posts)
AwsomeMrsFox Wed 08-May-13 16:56:24

Sorry I know it's been done loads of time before but I really really want it to be good news about electric UFH (and I'm hoping technology has moved on since the last glut of posts!)!

Old house, suspended floors, very well insulated house, will be laying porcelain tiles with very thin grout, 80sqm across 3 rooms.

The tile shop recommended warmup which they all claim to run in their homes as their primary source of heating. I think wet underfloor heating will not be great for us as it will probably cost a massive amount to install as it looks like it needs a special bracket between the bearers. Don't want radiators of any kind for many reasons.

I feel that electric UFH is a good option for us, but reading old posts on here I see that many people find it expensive to run. Do you think technology can move on and may be it isn't so expensive anymore, or am I fooling myself?

lalalonglegs Wed 08-May-13 17:15:37

Marking place.

GreenShadow Wed 08-May-13 17:24:07

We had electric UFH installed when we had the bathroom rebuilt a couple of years ago. We love it, but yes, the electricity bill has risen a bit although I'm afraid I couldn't say exactly how much is the UFH.

My main gripe is that the control panel is impossible to operate and even engineer DH can't sus out how to change the time settings. We only want it on in the morning for an hour or so in the Spring/Autumn but if it's on, it's on both morning and evening and for far longer than we would like. Only way to have it off in the evening is to turn it off at the wall and remember to turn to back on before the next morning.

PigletJohn Wed 08-May-13 17:32:41

electricity costs between two and three times as much per kWh as gas, but hey, it's your money.

AwsomeMrsFox Wed 08-May-13 20:14:47

But PigletJohn isn't that just a partial fact? Doesn't it depend how much you use of each? For my radiators to be effective with their relatively small pools of heat I have to crank the thermostat right up or add more radiators which presumable would draw more gas? With my (in my mind!) über-efficient warm evenly heated floor is there not a chance I might require fewer kw electricity?

I assume the kw consumption on the electric heating will vary depending on the thermostat?

I will also have gas fires to top up the heat if required (although the fireplace man has told me these won't provide much heat unless I have a glass front????!! Is that correct does anyone know?)

BimbaBirba Wed 08-May-13 20:30:51

I have underfloor heating in the conservatory and last winter I left it on a lot to dry the wash in there and....OMG! I now owe £1,000 to EDF because my consumption has gone through the roof compared to last year!

PigletJohn Wed 08-May-13 21:02:18

kWh is a measure of the energy used.

The amount of energy you use is proportional to how warm you make you house, and how long for.

It means "kilo (thousand) Watts x hours"

So a 1kW heater for one hour uses 1kWh, and costs 11.24p plus VAT for electricity, or 3.598p for gas (having checked the bill, energy from electricity cost more than three times as much as gas).

A 1 kW heater running for ten hours uses 10kWh; and so do ten 1kW heaters run for ten hours, so does a 20W light bulb run for 500 hours.

Because you are measuring energy use, the kWh used (which is what you are billed for) takes into account both the number of hours it is on, and the power of your heating device.

There is not the slightest chance that you will save money by paying three times as much for your energy. It will cost you more. As it is a ground floor, some of it will go towards heating the worms, and the air that blows out of your underfloor airbricks.

BTW an open fire sends most of its heat up the chimney to warm the birds, so yes, he is right.

PigletJohn Wed 08-May-13 21:05:26

correction

A 1 kW heater running for ten hours uses 10kWh; and so do ten 1kW heaters run for one hour, so does a 20W light bulb run for 500 hours.

The thermostat for electric heaters is generally just an on/off switch, not graduated. Modern radiators and boilers are capable of modulating their output up and down to match the demand.

AwsomeMrsFox Wed 08-May-13 21:45:05

That is an amazingly good clarification PigletJohn, thank you very much! (Even though it was not what I want to hear ;-) ).

Does anyone know how difficult it is to install wet UFH with a suspended floor? I so desperately want underfloor heating!

PigletJohn Wed 08-May-13 22:07:40

there's a fair amount of effort in it. You have to take up the floor, and insulate underneath it (which will greatly improve the comfort of hard floors, and cut draughts) so you need a good joiner or carpenter. You may end up laying a new floor if the old boards are not good. 18mm WBP ply (ir 25mm if your tiler insists) will be good. you will also need a plumber or heating engineer who is experienced in UFH, and possibly an electrician, as you will want to zone it per room so you can set times and temperatures individually. Special blending valves are used to control the temperature of the pipes. It will be vastly expensive to try to add these controls after the floor is down.

As all the floors have to come up this is a good time to clear up the rubbish underneath, and to remove the dust and cobwebs blocking the airbricks, and do any plumbing or electrical work that will be needed down there over the next 20 years (you will whinge if the tiles have to come up later). See if you can include trap-door access to the void. At modest extra cost you could have pipe stubs included so that radiators could be added later.

UFH is ideal for people who have more money than they need.

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