Underfloor Heating Cost...

peterc2609

Hi All,

Does anyone have electric underfloor heating and doesnt mind sharing their monthly electricity bill price?

I've got it downstairs and my electric bill is ASTRONOMICAL!

So wondering if something its wrong, or if its just normal?

matelodave

I don't have electric underfloor heating but I've a good idea how it works as I've got an overlaid u/f hot water system which would have similar characteristics - mine is heated using an air source heatpump and so is a lot cheaper to run.

Was yours retrofitted, how was it installed, on a slab., within a slab or on a suspended floor. Is it insulated underneath. What sort of flooring have you got over it?

Are you running it as the main heating. do you have economy 7.

All these aspects make a big difference to how much it will cost to run and how effective it will be

If it's installed in the floor slab, then it should work like a storage heater and you should be using E7. If it's been retrofitted and laid over the existing slab then there should be insulation underneath it to avoid losing heat to the slab, likewise even on a suspended floor you'll lose some heat downwards if there's no insulation underneath either the floor or the elements

If you are running it on full price electricity, then it will be expensive even though electric heating is 100% efficient you'll still be paying around 12p a unit - even more if you've got E7 and are running it all day on a peak rate tariff.

IMO electric u/f heating is OK for short time use in a bathroom but not as your main heating. If it was installed when the place was built and installed in a properly insulated floor slab and used like a storage heater on E7 it would be better but even then it's not ideal unless you are at home all day as you can't control the release of heat so it will be hot in the mornings and either cold of lukewarm come the evenings so you'd have to supplement it using peak rate electricity

peterc2609

Hi

It's installed throughout downstairs onto ply over floorboards.

There is screed and Karndean laid over it.

I probably made the mistake of removing radiators in the kitchen and front room when it was installed. So effectively it's trying to be the main source in these two rooms!

I've not got E7.

So basically, it's down and there's nothing I can do about it! Apart from use it more efficiently.

At the moment I have it on standby from 10pm till 6am, and from 930am till 2.30pm... Should I be doing this or should I be leaving it on all day at a lower temperature, so that it heats up quicker etc!

At the moment my dual fuel bill is around 280 a month... Of which electricity is around £200!

I don't have an electric shower or tumble drier etc so the majority of this must be the ufh.

Cardew

Electric UFH is, like any other form of electrical heating, 100% efficient and any electrical heating* is the most expensive form of heating available.


* storage heating is no more efficient, its advantage is it uses cheap off-peak electricity.

peterc2609

100% efficient... that sounds like a 'positive' thing... Yet, the cost isnt!

matelodave

A warm room will lose more heat than a cold room - it's a basic law of thermodynamics. so keeping it warm all the time will cost more than just heating it when you need it.

What you've got to determine is how hot you want the room, how long it takes to get to that temperature and then how long it takes to cool down. You can then optimise the switch on times and switch off times to reduce the cost as far as possible. ie don't turn it on too early and shut it down a bit earlier so that the room is beginning to cool when you go to work or go to bed.

It may not be easy to implement with your system but a programmable thermostat could allow you to set different temperatures at different times and on different days, so you could reduce it when you don't need the room quite as warm. Likewise controlling the rooms independently would also help especially if you don't need to heat the kitchen when you are sitting watching the telly.

Get rid of draughts and turn the temperature down a bit - we find that the overall even temperature from the floor upwards means we can set the thermostats to around 19-20 degrees (I could manage lower but my wife can't)

In the end, it's not a cheap way of heating especially if you are heating the void under the floorboards as well. All you can do is make sure that you are on the cheapest possible tariff for your leccy and that may not be a dual fuel one - do some comparisons with different suppliers for each fuel.

You could also read your meters a bit more frequently, say weekly for a while to see how any adjustments affect your consumption - it's easier to control if you can measure what you are using and when.

snowscreamer

I can give you figures. We have electric underfloor heating in our bathroom as the only source of heating in that room as the radiator was removed by the previous owners - this would not have been my choice!! As this is not our forever home and the room is relatively small I am just sucking up the cost of the electricity and the next owners can deal with it.

Anyway I reckon there is about 2 square metres of the underfloor heating laid down (room is 7 sq m but much of that is taken up by large bath and large shower); we have set the floor thermostat to 32.5 deg for 90 mins in the morning and again for 90 mins at night with it defaulting to 5 deg between times. We only raised the temperature a month ago because the air in the room was unbearably cold. It's now borderline comfortable (but very borderline!)

In the last month the underfloor heating used 90 kWh. In the summer it's been more like 6 kWh (although the thermostat was lower at 25 when that was recorded). I expect the last month was one of the coldest so I am hoping that next month it may be slightly lower.

90 kWh of electricity works out at £9.78. By comparison the rest of our house last month (110 sq m excluding the bathroom) needed approx 1200 kWh which cost us £30 in oil, and that was at lovely toasty temperatures. I certainly won't be changing the rest of the house to electric underfloor heating...