Wet UFH for Wet Room

[grahamA]

I'm looking for some advice on what options i have for the floor build up to install a wet underfloor heating system within a shower room. 

 

Most underfloor heating within showerrooms / bathrooms seem to be associated with the electric. This isn't the solution i want to use however as I have a lot of free energy in the form of hot water because of the renewable heating system we are putting in. The shower room will be located on the 1st floor and therefore the floor build up with be over existing joists. I would like to keep the floor build up to a minimum.

 

As we are tiling the showeroom I would ideally like a backer board we can install tiles directly onto that also accommodates 12mm/16mm UFH pipes, but can't find many options here. I would also like the shower tray former be able to accommodate UFH pipes but can't seem to find any options for this unless I rout the pipework routes myself within the former? is that even possible?  

 

Any advice on what options I have and how I should build up the floor would be much appreciated 

 

Thanks 

 

Graham

[markc]

As it’s on the first floor and any lost heat going down would still be within the envelope, why not just run pipework under the floor.

I am curious what you mean by “renewable Heating system”?

[grahamA]

Hi Markc,

 

I do have the option to run it at joist level however i'm wondering if a lot of heat would be lost between the build up of say a 22mm ply board and then a tile backer board overlaying the pipes?

 

By renewable heating system i mean a large multi-fuel burner with back boiler to serve the heating and hot water (we have an abundance of wood) and a heat pump back up with solar PV for when the multi-fuel burner isn't running. 

 

 

  

Edited August 3, 2023 by grahamA

[Nickfromwales]

Hi.

Most shower trays / wetroom formers are 22mm thick and cannot be 'cut into', however there are very few instances where I've run the electric UTH (under-tile heating) wire into the wet area, as there's very little point tbh.

I'm actually installing a Wedi setup atm for a client, and have allowed for the main areas / circulation space to be serviced by the UTH but not the wet area. When the shower is running, you'll only need a couple of degrees to raise the floor (wet) area to where you perceive it as "comfortable" (that has a thousand definitions btw) so I doubt it is worth making this job such a PITA.

There's a few solutions for the wet UFH in the bathroom, but I am a fan of (correctly installed) aluminium spreader plates. Then you just install 22mm P5 'weyroc' flooring with ply atop, and tile away. This isn't a very 'reactive' floor heating system as there is a lot for the heat to get through, hence it is very few instances where you see wet UFH in just a bathroom. The economics of just running that on its own for eg would not make much sense but with your circumstances it likely won't matter as you'll likely have the heating 'ticking over' vs on or off?

You will defo need this to be on its own manifold with its own thermostatic valve, if there's not UFH elsewhere in the home? If that is the case, you can possibly get away with just having a pump and a TMV at the buffer tank sending tempered water direct to this individual 'zone', but we'd need much more info about the system to advise definitively.

 

If you have this amount of renewable / lo-cost energy available, I'd make like easy and install UTH which you can run over any wetroom former etc. If you install the tiles over insulation tile boards as I am doing here, then the heat up time will be massively reduced and then it can just be timed for set-back operation, switching between comfort and economy temp to make it energy efficient.  

[Nickfromwales]

 

That’s 1200mm deep x 1400mm wide total width which will take a cubicle 1200mm return x 1000mm in-fold door. 
I see no reason to heat that area, given it’s a 1st floor bathroom that will always be at or above ambient, but I have run UTH over them before (at the clients request (insistence)). 
 

Most say they barely ever bothered with it tbh, where it was a 1st floor bathroom.

[markc]

Good morning, 18mm ply and a backer will slow heat transfer so you can’t expect fast warm up but you are not losing heat to ground and you have a good heat source. I’ve seen copper pipes laid just under the floor to heat upstairs bathrooms and while not energy saving or efficient it does work.

I live in a decent sized old railway property with solid walls and forget air tightness so I have a big boiler and live with some inefficiency, next one will be built from scratch and will be different but for now the little bit of water heat is ok.

just seen Nicks reply while writing this and there you have it from someone with much more experience than me.

[Nickfromwales]

7 minutes ago, markc said:

I’ve seen copper pipes laid just under the floor to heat upstairs bathrooms and while not energy saving or efficient it does work.

I routered the tops of the joists in my mates house, donkeys years ago, just enough to run about 50m of 8mm microbore directly under the chipboard (P5) deck. It was connected to the CH flow and return and was balanced with a single 15mm gate valve which was mounted under the removable bath panel. AFAIK, still works to this day, and I'm talking 20+ years ago. Zero insulation (as it was 1st floor / within the heated envelope anyways), and as the pipe was toasty hot the heat got through. 

Makes me shudder when I think back tbh, but this was a quick and easy way to get the result when there was a budget of <£50 lol. 

There are P5 deck boards available which are pre-routered, but I would suggest maybe contacting Wunda and asking them to design & supply a system for you that suits your exact circumstances. They give comprehensive support upon you placing a deposit.  

[Super_Paulie]

On 03/08/2023 at 07:54, Nickfromwales said:

I routered the tops of the joists in my mates house, donkeys years ago, just enough to run about 50m of 8mm microbore directly under the chipboard (P5) deck. It was connected to the CH flow and return and was balanced with a single 15mm gate valve which was mounted under the removable bath panel. AFAIK, still works to this day, and I'm talking 20+ years ago. Zero insulation (as it was 1st floor / within the heated envelope anyways), and as the pipe was toasty hot the heat got through. 

Makes me shudder when I think back tbh, but this was a quick and easy way to get the result when there was a budget of <£50 lol. 

There are P5 deck boards available which are pre-routered, but I would suggest maybe contacting Wunda and asking them to design & supply a system for you that suits your exact circumstances. They give comprehensive support upon you placing a deposit.  

I was going to do something very similar. Our bathroom is tiny, i guess floor space once the bog, bath etc is taken away is around 2m x 2m. I was going to just extend the the return from the towel rad to i guess loop round the area before it heads out the door. Might be ill-advised but it seemed that a return over a small area wouldnt cause any real issues.

I was also debating doing the same in the porch (1.8x1.8) as i dont want to run my UFH through there but simply to keep the air dry due to wet coats etc being in there. Happy to be told otherwise!

[Nickfromwales]

On 09/08/2023 at 09:53, Super_Paulie said:

I was going to do something very similar. Our bathroom is tiny, i guess floor space once the bog, bath etc is taken away is around 2m x 2m. I was going to just extend the the return from the towel rad to i guess loop round the area before it heads out the door. Might be ill-advised but it seemed that a return over a small area wouldnt cause any real issues.

I was also debating doing the same in the porch (1.8x1.8) as i dont want to run my UFH through there but simply to keep the air dry due to wet coats etc being in there. Happy to be told otherwise!

There are many ways to skin a cat  

[Andehh]

Ufh is great for drying the room out after a shower, otherwise through the winter you can find the floor is permanently damp!