Underfloor electric heater, between joists.

[atlasfever]

Hello,

I referred to this in a previous post, but the discussion focused on other elements of my post. So, specifically, is anyone aware of electric heaters that can be placed in the floor (with a metal cover)? I was at a museum recently that is in a period building of a similar age (georgian), and I did see that they had them. The brand was HCP and I could see that it written 'electric heater.''

Does anyone have any experience with this? Can heaters be placed in a wood floor? Not to sound like an amateur, but hot item near wood... I am specifically referring to electric as I do not want to invest in a underfloor radiator, which needs it's own plumbing/pump etc. I just wanted some 'back up' heating for those extra cold days. Otherwise, I plan to install a floating radiant (water) underfloor heating.

Thanks for feedback.

 

[Owain]

http://www.hcp-sasint.co.uk/trench_heating.php

There's no reason in principle why a suitable heater couldn't be recessed into a wooden floor. Plinth heaters are recessed into kitchen units. I'd be a bit concerned about dust accumulating on electric elements though.

http://www.stradarad.co.uk/index.php?option=com_content&view=article&id=35&Itemid=18

 

[Flyfisher]

Not to sound like an amateur, but hot item near wood...

I think the key word there is "hot". My understanding is that underfloor heating, because it has such a large surface area, works at a significantly lower temperature compared to the more usual radiators or even more concentrated heat sources such as fires or stoves. If it didn't, then the floor would be too uncomfortable to walk on.

Perhaps MdB can provide some temperature figures based on his underfloor system?

 

[MdB]

Perhaps MdB can provide some temperature figures based on his underfloor system?

40°C water in, 30°C water out and 25°C floor surface temperature (which is lovely). All figures approx.

You can get electric underfloor mats which can go under laminate at least. Not sure this is what you are thinking of though. I've heard mats are expensive to run but I can't see it would be any worse than any other sort of electric heating if insulated properly underneath.

 

[Flyfisher]

Thanks for the figures. Are they after a long period of running, i.e. at system equilibrium?

 

[atlasfever]

Thanks for the heating estimates.

Frankly, I'm keen to have underfloor heating, and I'm sure it will be fine for 3 of my rooms. But, for my two front rooms, which is like one space, there are 5 sash windows, large (1st floor), and I thought to add supplemental electric heating. Now, I just went to my flat and see that each window cove has joists running under them, so no clearance for a heater, if even only 100mm deep. Darn. So, I'm a little stuck. I could always go back to radiators, but I was really hoping to avoid them.

But, it's true, no point doing underfloor radiant if it's not enough. I learned today that chances of getting slim double glazing approved by council are rather slim. Bummer.

 

[Flyfisher]

But, it's true, no point doing underfloor radiant if it's not enough.

I didn't mean to imply that UFH would not be adequate because of its lower operating temperature. The much larger surface area of a floor when compared to a typical radiator means that it doesn't have to operate at radiator temperatures.

I don't know whether UFH is appropriate for your particular circumstances, but I wouldn't want you to discount the possibility based on my low temperature comments.

A proper system design would take such things into account.

 

[MdB]

Thanks for the figures. Are they after a long period of running, i.e. at system equilibrium?

Steady state figures.

Readings taken after 2hrs of running:
Outgoing from heat pump 40°C (guesstimate figure - very crude thermometer)
Return floor temperature 29°C (exact)

Outgoing to garden loops 3.0°C (exact)
Return from garden loops 6.8°C (exact)

Actual floor temperature 25°C (guess)