Spreader plates for first floor UFH

[cbk]

I'm taken the general recommendation to use Wunda for UFH design and see they offer a neat solution using aluminium spreader plates to fit regular UFH pipes between the joists for first floor bathrooms etc.   This avoids need to install pipes on top of the floor and eliminates the level changes that would arrise.  Has anybody had experience of using this system?  Seems to be a good alternative to electric systems  and I'm guessing a lot cheaper to run  form the ASHP.  One issue i can see is that the spreader plates and UFH pipes would need to be installed before the floor is laid which may be an issue in practice.  Any advice welcome.

[ProDave]

What floor joist?

 

If ordinary timber joists, you will need to notch each joist to allow the UFH pipe to cross to the next gap at the ends.

 

You can't notch the joists if using posi joists or I beam joists.

 

I did 2 small bathrooms with spreader plates and posi joists and it was a devil of a job threading long lengths or pipe through the web of the posi joists.  It was really only possible because they were small rooms and the length of pipe was not that long, but still a fiddly job. 

[cbk]

1 hour ago, ProDave said:

What floor joist?

 

If ordinary timber joists, you will need to notch each joist to allow the UFH pipe to cross to the next gap at the ends.

 

You can't notch the joists if using posi joists or I beam joists.

 

I did 2 small bathrooms with spreader plates and posi joists and it was a devil of a job threading long lengths or pipe through the web of the posi joists.  It was really only possible because they were small rooms and the length of pipe was not that long, but still a fiddly job. 

 

Will be posi joists, so I guess this rules out this option unless i add a batten to the top which can be notched for UFH pipes.  Sounds like you ran the flow and return through the web and I wondered if this runs the risk of creating air locks as levels change?   If you had to do this again what system would you use instead?

[Faz]

The electric mats are low wattage and not a nightmare to run I understand - I went for this in the end even though I had spare ways on the GF UFH manifold. In any event, the spreader plates are not that effective through a timber floor so having a mat under the tiles makes sense really.

[markc]

I agree, i leave my electric mats on 24/7 in the bathroom - use virtually nothing power wise and the cat loves the warm floor

[Faz]

Got mine first fixed to timers in the airing cupboard. Don't have a cat so that wasn't a consideration ?

[cbk]

Thanks guys, Electric mats seems the best option then.

[JFDIY]

If you use flexible pipe and plan your route, posi joist can be done with no loss in height.

 

Here's mine half way through

 

 

You just keep your loops within the joist at the ends and cross over/ under in the middle

Edited June 25, 2021 by JFDIY

[JFDIY]

The other rooms I have will be done using similar layout, but using the fit from below spreader plates as is easier I think

[cbk]

So does that mean you have not 'notched' the posi joists but instead run the return loop through the web of the joist up to the next spreader plate?  I assumed this would create an airlock problem but maybe you have a solution to this problem?

[Adsibob]

6 hours ago, markc said:

I agree, i leave my electric mats on 24/7 in the bathroom - use virtually nothing power wise and the cat loves the warm floor

I’m confused, I thought the general view was that electric UFh is more expensive to run than water based UFH?

[LA3222]

I went for water based ufh in a pug screed across the entire first floor for a couple of reasons:

 

- 5T of sand cement will kill alot of sound and the floor is rock solid.

- can pump cool water in cooling mode which means the effective floor area for sucking heat out has doubled.

[ProDave]

10 hours ago, cbk said:

So does that mean you have not 'notched' the posi joists but instead run the return loop through the web of the joist up to the next spreader plate?  I assumed this would create an airlock problem but maybe you have a solution to this problem?

No problem with having a loop of pipe going down.

 

It is when you have a loop of pipe going UP that you open up the possibility of air collecting in that loop and an air lock.