Best flooring to enable UFH heat pass through? Bathroom floor

[Andehh]

We are looking to have wet UFH installed under our main bathroom floor.

It is a new build house with joists 600mm apart.

I was intending on asking the plumber/builder to noggin heavily the floor, pack it out with Kingspan/celotex and then run UFH pipes through the notched noggins.

What subfloor am I best to run over this for maximum heat throughput? Currently the house is 22m chipboard, but wood being an insulator...is there a better product to use?

Going with WET UFH due to it being in a few other areas of the house, and the manifold having a spare port for it. Keeps the house consistent and easily controlled from our central Evohome system.

Many thanks,

 

[bernardgreen]

Thermally conductive ceramic tiles ( ceramic loaded with aluminium nitride ) are available but good quality ones are very expensive for domestic use.

I happened to be looking this morning at thermally conductive ceramics for heatsinking an electronics module. The difference in thermal conductivity between "normal" ceramic bath room tiles and and those intended to conduct heat is surprisingly large.

 

[tomfe]

I would screed between the joists to add thermal mass then a cement board then just tile. Any floor tile will do.

 

[Andehh]

Thanks for the reply guys

I am hoping to treat it more as a 'radiator' then as an actual typical UFH in screed setup. Idea is to run it for an hour or two in the evening to warm the floor whilst you dry yourself & an hour in the morning prior to brushing teeth etc.

We have our en suite wetroom (but with 22mm chipboard & tanking) like this & it works fantastically to dry the room out, but with this being a bath setup bathroom, we don't need the prolonged heat - just the burst for when you get out & stand there drying yourself.

This is why I was hoping there would be some form of 22mm flooring that didn't insulate as much as wood does. Concrete backboard with the similar rigid to 22mm chipboard?

 

[Tipper]

There's a useful table on page 10 of this brochure from Hep2O/Wavin.

file:///C:/Users/MC%20Study/Downloads/4186%20Hep2O%20UFH%20A4%20Product%20Guide%20(UF437)%20WEB.pdf

 

[Steve]

but with this being a bath setup bathroom, we don't need the prolonged heat - just the burst for when you get out & stand there drying yourself.

I would point out that UFH, whatever the arrangement, will take at least an hour to actually give out any useful heat. If you want a burst of heat, forget the UFH and fit an electric downflow heater on a pneumatic delay switch. UFH is totally useless for what you propose it for.

 

[cjard]

The problem is, you seem to want warm tootsies, which means have your bathroom floor at a temperature a (potentially) 37 degree human will perceive as "warm" - call it 35 degrees plus

The temperature is controlled at the manifold, so all floor zones operate off the same temperature water, and if you have your manifold water at 35 you could potentially be boiling the rest of the house

To be perfectly honest I'd install ufh in your bathroom but run it at the same sensible temp as the rest of the house (say, 29 degrees or lower, if your floor coverings elsewhere are conductive, and the house is a new build/well insulated and airtight) and have an electric ufh system to boost the tile heat to warm tootsies in the morning and evening. It'll cost pence to run because it's only lifting 6 degrees, and it's far more controllable/timer capable

 

[mointainwalker]

"
I am hoping to treat it more as a 'radiator' then as an actual typical UFH in screed setup. Idea is to run it for an hour or two in the evening to warm the floor whilst you dry yourself & an hour in the morning prior to brushing teeth etc."

I don't understand your comment. The typical UFH in-screed is designed to be a radiator because of the mass of the screed and an hour or two of activation will - in my experience with a fairly tight pattern of pipe - will give you what you want and you haven't mentioned any limitation of floor thickness. If there isn't , use UFH in-screed, if there is, use electric-matting under tiles, especially for the intermittent bathroom usage .

By the way, above cjard mentions a floor-temperature of 35C +. It may or may not interest you that the regs calls for a max floor-surface temperature of 30 C: this was due to health problems in the 70's when there were very high-temperature installations in public buildings. In truth though, these conditions were in areas where people stood/sat for long periods and not very relevant to domestic bathrooms.