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Electric UFH in bathrooms


Bitpipe

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We have a MBC house with 3 bathrooms, two are in a cantilevered section that sits over the porch and the ensuite is at the rear and is over the living / dining room.

The cantilevered section is well insulated (400mm of Warmcel) but I have been advised that cold bathroom tiles under feet will not be tolerated!

Our main heating is wet UFH on the ground floor only (under the suspended timber floor).

As a last minute measure (and I mean removing plasterboard and re-tacking kind of last minute), we made provision for electric UFH by running a conduit into each bathroom and adding boxes for a stat plus fused spur each.

Plan to put the cheapest 100W mat system on the cheapest 6mm backer board and have it as a just in case system. Was planning to use 9mm ply to build up the sub floor so this will get me there or there abouts.

So, two questions:

1) Anyone have experience of using this system and any tips? Tiler has offered to lay board and mat for £40sqm (areas are a few sqm each). 

2) Any of the MBC owners club care to comment on the feel of tiles under feet in 1st floor bathrooms?

We have also not put any UFH heating in the basement as the rebar was too complex to lay pipe in during the pour. Basement is 300mm slab on 300mm EPS and walls (now plasterboarded) are 300mm with 200mm EPS so a very consistent temperature. It will also be tiled and resisting the urge to also lay electric UFH as a just in case measure.

 

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1 hour ago, Bitpipe said:

2) Any of the MBC owners club care to comment on the feel of tiles under feet in 1st floor bathrooms?

One of my major regrets is not putting underfloor heating in our bathrooms, despite having specially recessed the floor to ensure there was space to do so.  Our tiled bathroom floors DO feel cold in winter, despite the rest of the house being at a comfortable temperature.  I'm kicking myself for not taking the opportunity to put down at least electric matting if not wet UFH.  

I also have had a different experience with heating compared to a lot of people with MBC houses.  I suspect it's largely about solar gain, but even with the recent warm weather, our house has never been particularly warm.  I'm not saying it's ever uncomfortable - far from it - but I get the feeling our heating system was switched off a lot later this year than, say, Jeremy's (at least partly due to his house's microclimate).

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Jack that's very interesting to hear as I wasn't going to bother with any ufh in the upstairs bathrooms. I could run a manifold upstairs for wet ufh or maybe make do with electric. I'm not sure how they stack up financially. 

Does anyone also have any thoughts on wet vs electric for towel rads in a passive house. I think the plumber quoted about £800 for a separate loop to run them wet. They would need to be separate to the ufh as running at a warmer temp and also year round.

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We went wet as the slightly higher cost of install was outweighed by the cost of the units - electric rads are quite a bit more expensive than wet.

Electric UFH is not that expensive for a small area - I'm using the UFH store's cheapest system which is just 100W - figure that I will only want it on when the bathrooms are in use. Have been advised that the mats should be run to all accessible areas of the bathroom, including just under the bath, as the heat does not spread far and wide - which is probably good for our type of house.

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Hi,

We have traditional UFH in our ground floor and basement and rads + towel rads in bedrooms/bathrooms upstairs.

If i was doing it all again I would do UFH everywhere. The idea at the time was that the 1st floor heating would hardly (if ever) get used - but the reality is it does make a difference and the control system on the UFH is much better than the one we ended up with on the rads. An electric UFH system would probably work fine - they key thing is to have a seperate thermostat controlling heating of each room.

- reddal

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  • 3 weeks later...

So I'm now looking at what brand to order for the bathrooms, I need one each of 2.5m2, 3m2 and 4.5m2 mats.

Going to go for a 100W system (100mm spacing) and did consider the loose wire but they look fussy to install.

Is there any real difference between the value and mid-range systems that the UFH superstore stock?

Haven't made a decision on thermostats either, could go for the budget white ones or go all out for the Heatmiser Neos and tie them into the main UFH controller using the hub, enabling wireless control - however this does add a few hundred pounds of cost.

Also, any advice on what primer to use under the backer boards and on top of the levelling compound?

 

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They should come with a primer, but any flexible primer will do. I use N&C NicoBond stuff and it's shit hot. Don't know if they're nationwide though? Most are a neoprene emulsion so anything with that tag should suffice, but realistically anything that doesn't skin over ( like PVA ) is the better option IMO. It's a lot easier to get the double sided tape to stick to a tacky primer vs a primer like PVA which has skinned over. 

For one stop shopping get some of this

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Thanks Nick, UFH SS do offer all-in kits with primer, roller etc but the thermostats are pretty basic so would rather pick it up separately. 

Just remind me how many times I need to use primer - on the OSB, again on the backer boards and again on the latex prior to doing the membrane?

For the standard bathrooms, do I need to prime the latex before the tiler starts their work or leave it to them?

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Flexible primer between EVERY layer, and then the supplied primer under the mat. 

I would go for a self-learning 'intelligent' controller. This will ascertain how long it takes for the floor to get to temp, at the set time, and then after a few cycles will adjust itself accordingly to minimise the on time. One assumes it will use the same info to turn off accordingly too. 

Leave the tiler to his / her own devices. Ask them about what layers will be primed, with what, and why. Allow them to tell you what they're doing, NOT vice versa. ;)  You don't buy a dog so you can stay up all night barking yourself. 

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Thanks - and any advice on the mats themselves?

There's about £70 difference (less when I add the Quidco cash back and remove VAT) for all three mats between mid-range Prowarm and the cheaper Thermoflex. The latter is marginally thicker 3.5mm vs 3mm.

 

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The only prob with the acrylic primers is that they tend to stick to heavy contact items after curing ( knees when knelt on etc ) and are quite a thick, defined, layer. Liquid ( thin coat ) primers are my weapon of choice vs this type of primer ( which is like a thick coat of paint ) as they don't just prime already suitable substrates but coat them with the bonding layer that's actually required. 

That Bal product is more something I'd expect to use when waterproofing, and as your priming between layers I'd choose something else. I can give you the contact details for N&C and see if you can get their stuff locally or direct if you want. 

Edited by Nickfromwales
Edited to make sense ( after too much Bud. )
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10 minutes ago, Nickfromwales said:

The only prob with the acrylic primers is that they tend to stick to heavy contact items after curing ( knees when knelt on etc ) and are quite a thick, defined, layer. Liquid ( thin coat ) primers are my weapon of choice vs this type of primer ( which is like a thick coat of paint ) as they don't just prime already suitable substrates but coat them with a layer that's not really required. 

That Bal product is more something I'd expect to use when waterproofing, and as your priming between layers I'd choose something else. I can give you the contact details for N&C and see if you can get their stuff locally or direct if you want. 

Thanks Nick, I found them on-line but they look to be trade only, I might be able to get an account out of them. What quantity would I need to do the various stages of the 3 bathrooms (3, 5 and 7 m2)?

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I edited my last to make more sense O.o Damn you Budweiser. 

A 2.5 ltr bottle of that stuff has lasted me a bout 3 jobs ;)  Very good mileage. Watered down for fist coat, to reduce porosity, and then applied neat during laying ( stays horribly tacky so best to 'lay as you go' when used neat. 

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Warm up is overpriced IMO. They do, however, a very good controller and for the sake of the extra £20 this one talks to your smartphone. Different colour options too to better suit the decor. The controller isn't cheap, but it has bags of features like running costs monitoring etc. 

This Devi mat is good, and the price is great. You can couple this to the warmup stat no probs ( and the controller comes with the thermostat probe to complete the kit ). 

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Fwiw, I've fitted a load of the Dron ( German iirc ) stuff and never had an issue. Can't see any difference TBH, or more importantly where the extra money goes. Some, possibly warmup, do a lifetime / long / extended warranty on their cables but that's with very their very strict installation guidelines adhered to to the letter. I've heared of one instance where a warmup cable failed at multiple points in a new and very expensive bathroom. They came out with an imaging camera and cut 3 sections of floor out. They then remove sections of the wire and took them away for analysis. After a long wait, and much chasing up, they admitted liability and paid around £7k for reparation work. :o. ( after being told it wasn't going to go away that is ). 

With that said, it adds merit to go for the known makes / reputable brands as they are typically the ones that offer a warranty that's actually worth the paper it's written on. The above was the only instance I've heared of these types of kits catastrophically failing, with one other warmup kit I fitted going to earth fault but I found out the floor got flooded so I disconnected it and told them it's party over. I think they've since reconnected it against my advice and it's working. 

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I used a loose wire system under the tiles in the bathroom of our current house.  Easy to lay, the only challenge was working out the layout of the wires.  The nice thing is that you can run the wires around things like the toilet or any projections, and you can have a lot lower power by just increasing the wire spacing.  I bought ours as a kit on-line around 10 years ago.  It was the cheapest I could find as I thought we'd not be staying in the house long.......................

It's been 100% reliable, with an easy to use thermostat/programmer, and has a sensor embedded in the floor to control the floor temperature. 

Installing it was easy, just prime the floor, layout the wire and hold it down with the tape provided in the kit (the primer is needed to make sure the tape sticks, I believe).  Tehn just apply tile adhesive and lay the tiles normally, with the wires embedded in the adhesive.

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