Wet Room & Electric Under Floor Heating

[Trist]

I'm having an extension built at the moment with a shower / wet room in it. I'm looking for advice on installing electric underfloor heating. The builder tells me he can't find anyone to fit it and that everyone he's spoken to has advised against it.

Has anyone on here had any experience of fitting it or using it? What might be the pitfalls?

Ground floor bathroom, tiled.

Cheers
Trist

 

[Taylortwocities]

IMO, electric underfloor heating is OK just to warm your tootsies, but less than wonderful to heat a room space. Further, if you have a solid floor, you'll need to have it coming on quite a while so that the concrete can heat up, unless there's a lot of insulation under the screed.

 

[Doggit]

I haven't done this yet, but as I'm investigating it, I'll pass on what I've found so far. It's going to depend on the floor the builders are fitting, but essentially, you'll glue down 10mm XPS insulation boards to what I assume is going to be a concrete floor, tape the electric mat to the floor (but not under toilets, baths or fittings), and add a thermostat, and then either cover the mat with a latex self leveling compound and then tile, or butter the back of the tiles, and lay them straight on to the electric mat. If you're just looking to warm the floor, then 100 - 150W/sqm is fine, if you're looking to heat the room, then you'll want 150-200W instead. If you've got a 10sqm room, then a 150W system will consume 1.5Kw per hour, but over the course of a day, it won't be running continuously, whereas taking the chill off the floor means it'll be running continuously for the time you're using it.

 

[flameport]

What might be the pitfalls?

The most expensive form of heating available
Takes a couple of hours to actually heat anything
Will make the tiles warm but unlikely to heat the bathroom to a usable temperature
When it breaks, repair involves hacking holes in the floor. That is the point when most people fit a radiator instead, which is what they should have done in the first place.

 

[ericmark]

Yes it was a failure. It was fitted with the idea of drying the floor so wheel chair would not slip, first install ripped out again as builders damaged it with floor tiles, second one did work, have to select special type with earth around heating wires or earthed mat above. So installed and working, takes good hour to warm up, once shower is used it's cold again, takes 20 minutes to re-warm up.

6 months latter the thermostat went, another 6 months and yet another thermostat, another 6 months and the under floor sensor went, it got stuck in the pocket so could not renew without ripping up tiles, so worked with just air temperature for a time. But so useless gave up.

With the fan running there was not enough heat from the tiles and they were at the 55°C maximum permitted to keep the wet room warm when drawing air from a cold hall, it needed the towel rail to keep room warm, in fact the towel rail on it's own was good enough.

In all it was a total waste of money, for tiles outside a shower it worked well, it was that what made me think it would work with wet room, but with wet room total failure.

 

[endecotp]

If you want a floor that feels warm underfoot, put down cork tiles. No need for heating.

 

[deadshort]

What might be the pitfalls?

The most expensive form of heating available
Takes a couple of hours to actually heat anything
Will make the tiles warm but unlikely to heat the bathroom to a usable temperature
When it breaks, repair involves hacking holes in the floor. That is the point when most people fit a radiator instead, which is what they should have done in the first place.

I agree with all of the above ! from bitter and expensive experience !

DS

 

[Trist]

Thanks to all for valuable advice. I have decided to bin this idea. Particularly the points about system failure and ripping up floor.