Underfloor heating - electric vs water systems

[Loueytb3]

We are getting quotes in at the moment for an extension (orangery) which will have underfloor heating put into it. One company recommends putting in a water based system, the other two only use electric systems. I can't work out whether one system is better than the other. I know that the water based one is more expensive to install but cheaper to run. Does anyone have experience with either of these systems? It is going to be quite a big room so we need to get the heating right. We are going to change the boiler anyway so that won't be a consideration/hindrance on what we choose.

we have had electric in our last two house for the complete down stairs.
our bills are minimal.
The water ones are run off the same type of system as the rads are they not?
if the are they will work out more expensive to run due to gas prices.
we only use the shower in our house and the taps for gas and the gas bill is the same ish as the electric and thats even after having this cold winter.
the other thing we found good about the electric was you can decide where to lay it.
My dh laid ours with the electric self laying cables.
We didn't run it under where our kitchen units were just under the plinths, no point warming a cupboard or our fridge.

what are you having on the floor? we have porcelain in the hall and kitchen with smaller grout lines, so laid the cables closer together to generate more heat, we do have a rad in the kitchen but its more to look as never have it on.
In the living room we have larger grout lines and ceramic tiles and it does get alot warmer in there.
but when the house is warmed up it stays worm for ages.
Your in a good position as your having an extension so the floor wont need lifting and re screeding it you go for the wet.
that would have been too big a job for us.

We had electric underfloor installed in our kitchen and after using it for a few months stopped as our electric bill went through the roof. I thought the water was expensive to install but cheaper to run. Check how many kwh the electric one would use per square meter and times thatby the khw cost on your elec bill (approx 12p) and the number of hrs it will be on for. That will give you and idea.

Our electric underfloor heating is OFF as it is so fecking expensive. Bit pointless having it really

My parents had electric put in purely because they were worried that if they went away the water version might freeze in the same way as pipes might.

I assume that there is something in place to stop it freezing, but if not then that is a major mark against water in my opinion.

We have wet underfloor heating and the plumber put antifreeze in the pipes.

I think the cheapest combination in terms of running costs is water based ufh coupled with a geothermal heat pump

Water is more expensive to install and cheaper to run. If I was doing say just a small bathroom floor, I'd go for electric. But for a decent sized room definitely water.

Have a look hear

www.floorheating.com/FloorHeatingBlog/?p=28

Which also have some info on it

energy from electricity costs two or three times as much as energy from gas.

Wet UFH is more expensive to install, especially when retrofitted to an already-built house. Not so bad to add when you are having e.g. an extension built as long as you remember it before the floor is laid.

Thank you! This is all really helpful and confirms my instinct to go with the wet system.

Its been difficult to get an unbiased opinion because the companies obviously have vested interests in the systems they used - the companies that don't have their own plumbers are plugging the electric systems and the company that does recommended the wet system. One of the companies actually said that they had heard of a child being burnt after sitting on a rug over an electric underfloor heating system which had concentrated the heat. He was scaremongering trying to use it as an example to say why the electric system they used was better. Needless to say I wasn't impressed.

We have to move and replace the boiler anyway, the new room will be a new build so they can put the pipes in the screed floor. Good to know about antifreeze in the pipes - will check that is standard.

Is there anything we need to think about re flooring?? We are still undecided about what flooring to go for but are thinking of amtico/karndean because we have small kids and it will lead directly onto the garden so we need something hard wearing which will clean easily. Do we need to think about furniture placement before they lay the pipes?

Maybe a stupid question!

Will the water underfloor heating be connected to the rest of the central heating in the house or be separate?

We're going to be in same position maybe next year and so far one builder says just put rads on wall.

I think it will be joined to the central heating system hence the need for a new boiler as our current one wouldn't cope (it's getting on for 20yrs old).

it will be run from the CH system but has a blending valve so that the water circulating through the floor is not so hot as the water circulating through the radiators. This means the floor is bigger but not so hot, its extra size means it can deliver plenty of heat to the room.

re flooring - i was told that if you were going to have wooden flooring it had to be engineered wood if you had UFH (i assume to allow for expansion/contraction)

yes, real solid wood will shrink a lot due to being very dry. It may also warp or crack. Engineered wood is basically a fancy plywood, and hardly moves at all.

I think real wood is beyond our budget but in any case, too worried about spills from small kids.

We have both: a water based system in the extension and electric in the old bit (though still the same room) as we couldn't afford to dig up the floor. The wet system is lovely but we never turn the electric system on because we are scared of the cost.

You can use real wood with underfloor but generally best on new builds where is is absolutely no damp in walls which in turn gives mositure/humidity into rooms hence buckling etc. With ultra dry rooms it can be used successfully. Underfloor heating is run at a low temp so there is very little movement, its the moisture thats the problem.

Electric heating is fine for small rooms but will not provide proper heat in a room and you would need rads to compensate this. I used to work for consultant engineers in M&E dept so I learnt a lot. A conservatory can be freezing in winter and elec floor will not heat this.

You do need a newer boiler system and manifold system which is a set of big pipes with taps on. Very efficient as runs at low temp against a rad which has to be hot. Plus you dont get cold spots.

If I had my time again I would go for tiles throughout, tiles allow great heat penetration and easy to clean.

I've heard it's also better for your bills if you leave the underfloor heating on a very low setting all the time (not in the summer months obviously!).

With regards water UFH, can it be used with a solar thermal system ? I thought that given that the water doesn't need to be as hot as that required for radiators, solar might get you some of the way but I guess if it runs through the same boiler system the benefit would be undone by the large volume of water in a solar system ?

solar water heating is usually very low power. Find out how many kWh per day the system is expected to deliver in winter. I expect it will not be many. A typical well insulated room needs between 1.5kW and 3kW for as many hours as you want it to be warm. (e.g. 10 hours at 3kW needs 30kWh)

Solar tubes usually are said to save about half your hot water costs. In my case that would be about 20p a day in summer. No doubt they would provide less in winter as there will be less sun and the heat losses will be greater.

We've built an extension with wet underfloor heating with Amtico on the top. We love it, the heat is really cosy and gentle. The biggest problem we had was waiting 7 weeks for the concrete floor to dry out before the Amtico could be laid.

During the day when I am in on my own I have the underfloor heating on, so the boiler is running intermittently for it, but only the kitchen is being warmed up and not the whole house, which is great.