overlay Wet underfloor heating

[Osteosingh]

I am looking to lay underfloor heating over existing ground floor concrete 1974 floors.
Is it best to go with the overlay premade panels and if so which ones do people recommend, or get someone to lay down pipes and matting and a thin screed?
I want to keep the height as low as possible and will welcome any suggestions

 

[muggles]

NuHeat LoPro

 

[compact]

Expanding on the above question.
Has anyone come across any good reviews of the different systems/suppliers?
They all look similar, but I am sure some are better than others. Shops will most likely push which sells best / with best profit.
Plumbers and installers, similar.

So far I have come across:
ProWarm, NuHeat, WundaFloor, PolyPipe, Roth, SpeedFit, Thermo Flow.

We're looking at Roth Clima Comfort Compact System, which is 17mm once screed is applied and ready to be tiles on.

 

[Osteosingh]

Roth Clima Comfort Compact System

What made you go for the Roth system and have you fund a good retailer for them?

 

[dilalio]

Wet UFH works best with a decent thickness screed over it... 70mm or more... as you are trying to create a thermal store that absorbs and then radiates the heat - hence the long warm up and cool down times.

 

[compact]

What made you go for the Roth system and have you fund a good retailer for them?

I came across them through a local firm in . They're a large German company.
I always associate German companies with quality (dieselgate excluded). They do a heat output profile.
I guess it's a toss up between companies as the products are similar.
As long as your floor is sound and the pipes are good quality, anything that can go wrong should be easy to get at and replace.
I'll let you know how it goes in a month or so.

 

[compact]

Wet UFH works best with a decent thickness screed over it... 70mm or more... as you are trying to create a thermal store that absorbs and then radiates the heat - hence the long warm up and cool down times.

Yes I agree WFH came from that premise. However if you want to retrofit on suspended timber the build up would result in short doorways large step into the room and /or tiny 1st step at the bottom of the .
Overlay systems aren't as efficient,but seem a good alternative to radiators.

 

[dilalio]

There are other methods with suspended floors and excavation for solid floors - there’s no easy way out for optimum performance.

 

[compact]

An update, after reading too many articles, posts etc.
We've decided again an overlay system using the eps type boards (Wunda etc) and gone of a lego board and screed overlay.
To be specific Uponor Minitec boards with Speedfit 10mm piping and Mapei screed.

We strengthened our timber floor with legs screwed into the joists, as there was a little bounce
We laid hardback and some self levelling to bring the floor level (the room is made of 3 rooms and an extension, 2 had suspended concrete floors and 2 suspended timber)

The Uponor boards and very simple of lay, if you can stick down a Panini Sticker you can do these
The pipe laying is the more challenging part, but still fairly simple.
You lay it in a spiral, then at the centre, you spiral back on yourself, so you just have to remember to leave enough space on the 1st spiral
i.e. 1st spiral 6 spaces, so when you come back on yourself the pipe sits at space 3, so all pipes are 3 spaces apart.

From here we will be screeding, Ditra type matting and then tiling.

Benefit:

• Overall height of Boards, Pipes and Screed = 15mm. This was important for us, as we were ruled by the Bifold doors (installed a little low, or floor a little too high!!)
• Some EPS systems insist of overlaying the eps, so more building and less responsive
• More flexible than eps, as our floor still wasn't completely flat where the rooms joined
• We had read problems of the boards de- laminating eps to foil top, something about bubbles between foil and screed etc.
• Quicker to lay boards (but maybe not pipes)
• More flexibility for pipe layout
• Easy to cut with a stanley knife and lay around design of kitchen (to use less boards)

Benefit or drawback?

• More screed for a thermal mass?
• Feels more like a proper WFH system with more screed, which binds to the subfloor better than just eps

Drawbacks:

• Smaller pipes, so possibly less heat output
• More screed so possibly slower heat output than just pipes in EPS
• More screed so less DIY
• More expensive, as boards + screed is more expensive than just eps

So now we will clip down the pipes, screed, Ditra style matting and tile.

 

[AnotherMatt]

Hi Compact,

Exactly the kind of info I've been looking for. I've got a similar scenario i.e. a structural floor that is partial solid concrete and partial suspended T&G floor due to a knock through. Minimal rise required to avoid step/ ramp from Minton tool hallway.

I'm poised to go Wunda 16mm EPS route due to no current insulation and impossible to retro fit. So I'm curious if you have insulation under your structural floors since the Uponor system doesn't feature any.

Cheers!

 

[compact]

We insulated under the Timber, we didn't under the concrete.
You can't go wrong with insulation, the more the merrier I say.
We don't really notice any difference between the two parts once it's on.

We generally turn it on like radiators at the moment, so instead of keeping it on all the time to build be a heat mass, it comes on in the morning and evenings.
Being closer to the surface and less mass to heat means quicker response, but probably not as efficient as the traditional WFH systems

It is responsive and quick, however the heat doesn't spread far.
Between the pipes it warms up nicely, but at the edges it can get cool.
i.e. measure and plan where your pipes stop.
You don't want to heat under cupboards, however I'd advise stopping close to the plinth so you don't get cold toes. There is an inch at one side of the kitchen which takes ages to heat, wish I had measured closer.