Electric underfloor heating options over suspended wooden floor 50m2!

[Lombear]

I am currently undergoing a house refurbishment and we are now working on the downstairs open planned kitchen/family room which is 6.6m x 7.6m. We originally considered the wet UFH however due to cost we decided not to proceed on this basis but to have radiators.

I have been concerned about heating such a large room so have chosen radiators that will adequately heat the room, but now am wondering if perhaps electric UFH would be useful to add the underfoot warm feeling.

The floor is a suspended wooden floor and my builder has suggested 100mm celotex between the joists. This alone is very costly for the products and the labour to do the work. He is going to finish the floor with 22mm caber flooring.

We are undecided at the moment if we are going to go with either engineered wood flooring or Kadean.

So depending on what the final flooring chosen what suggestion would you have for finishing each.

Woodfloor:
100mm celotex between joists
22mm Caber under
foil UFH under
engineered wood flooring.

Do i need an additional insulation between the caber flooring and the UFH foil if i have already added 100mm celotec below the flooring?

Kardean:
100mm celotex between joists
22mm Caber under
electric UFH under
latex screed under
Kadean finish floor.

Can i lay the UFH on to the caber flooring or do i need to add some floor ply so i can latex?

Do i need to do the 100mm celotex but instead have a lower cost thinner insulation above the caber flooring?

The area I need to cover is roughly 50m2 but i need to take off areas where the kitchen units/island etc will be. None the less this is still a sizeable area. Are there kits available that can cover this space. I have seen some 100w loose cable options that could do 36m2 but this may not be enough.

Any suggestions/advise please would be very much appreciated.

Many thanks.

 

[flameport]

Unless you are really desperate to have a warm floor, don't bother.
Electric UFH costs a fortune to run, and will make the installation cost of wet UFH look cheap.
100W means 100 watts per square meter - 5kW for the floor. At 15p/unit, that will cost 75p for every hour it is switched on.

 

[Ian H]

Is that 100w at peak though?

We have it but only 18mtrs in our kitchen and it is lovely. The guy that I bought it off reckoned, for the average user, it would cost £6/mtr/year.

I thought that was *******s but when ours is warmed up I turn it down loads so I'm not sure how much power it's using to maintain the heat.

I wonder if there is a more fancy controller that will show its use in watts?

 

[Diyisfun]

Is that 100w at peak though?

We have it but only 18mtrs in our kitchen and it is lovely. The guy that I bought it off reckoned, for the average user, it would cost £6/mtr/year.

I thought that was *******s but when ours is warmed up I turn it down loads so I'm not sure how much power it's using to maintain the heat.

I wonder if there is a more fancy controller that will show its use in watts?

WHAT...Not controlled by thermostat.??

 

[Ian H]

Yes, but basic 7 day thing. It tells me air and floor temp but not how much power it's using.

 

[oldbutnotdead]

I'll leave the pros and cons of UFH to others. With your insulation query, you definitely don't want additional insulation above the heating mat. Your builders' suggestion of 100mm Celotex between the joists is one way of achieving the minimum thermal efficiency required for your new floor- if you've got the space between floor and subfloor then you can use less efficient (but much cheaper) insulation- 170mm of rockwool for instance- but you then have the faff of stopping the stuff dropping onto the subfloor.

 

[Lombear]

Thanks all. The renovation is taking its toll financially and emotionally as I am sure that is no surprise to many. I have decided not to proceed with the UFH. I feel that the cost of initial installation and potentially cost of use will be to high. With the insulation and wooden floor I am hoping it will still be a comfortable environment.
Thank you for your responses.