Single Zone UFH Help in bathroom, so many questions

[AcidOverride]

Done a fair bit of reading and spoke to numerous plumbers/heating engineers and I get so many different answers to my question. By nature I'm a pretty inquisitive bloke and like to know how things work and if its the best way to do things. So my first question is does a single zone UFH setup need 2 port zone valves adding for both the new UFH and the existing radiators or can you just run the existing radiator runs into an UFH pump/manifold? Or do you even need a pump at the manifold, why not just stick the existing flow in one end and the return in the other so it works with the radiators? Obviously if you want to run them on two dif stats you need the 2 port zone valves but just curious as to the reasons why the other options arnt viable. Oh and I have a vaillant ecotec plus 832 combi.

My second question is where to put the underfloor heating. This is for an upstairs bathroom with a timber floor. I've seem people Celotex between the joists, run the piping then screed between the joists. I've also see people use some aluminium plates you fix between the joists then board over. Then I've see this TileFix 18 that sits on top of the floorboard that has runs in for the pipes and you tile straight to it. I would be using moisture resistant chipboard and Id be adding noggins too to make it solid and have as little deflection as possible. I guess the TileFix then acts as a decoupler if you use that. If I opted for the pipes been run under the chipboard using the aluminium plates (don't like the idea of screed) I would prob go for a 6mm hardiebacker over the chipboard before tiling. But will the heat still make its way through 18mm for chip, 6mm or cement board, adhesive and tile?

Thanks

 

[ShaunCorbs]

Yes needs to be separate eg s plan with the rads 2x 2 ports

Yes you need a manifold and pump else the high temp will damage the floor / tiles

I would infill the joists with insulation then fix 2x2 to the sides of the joists 18mm lower than the top of them then fix 18mm ply to the 2x2 so everything is level with the top of the existing timbers (if the existing timbers arnt level you can adjust at your 2x2 fixing stage )

Then overboard with ufh panel that you can tile straight over

 

[AcidOverride]

Thanks for the knowledge. So the main reason for having the UFH on a separate stat is because having the same heat running through the floor as the radiator would be just too high? Makes sense, I wouldn't fancy standing on a radiator on full whack.

Oh, infill the joists the ply on 2x2 battens? That's one method I've not come across. I guess doing it this way though I'd run into issues when fitting the 22mm deep shower tray which would need tiling over. But I believe they do a 22mm version of the TileFix. I just wonder if it would be solid enough 🤷‍♂️

 

[ShaunCorbs]

Or you could 3mm ply under the tilefix board first eg sheet the whole floor except the shower area then a thin skim of self lever over the tile fix board to encase the tubes and bring you to your final height eg level with the shower tray ready for tiling

Or put the tilefix ufh boards down and do a 4mm self leveller over the floor

 

[AcidOverride]

And is the floor solid enough with inlaying the ply between the joists on 2x2s? I guess its a good way of keeping the height down and getting them pipes directly under the tiles, just last thing I want is cracked tiles and cracked grout.

 

[ShaunCorbs]

Yes also this will stiffen the floor up loads and at the time if you want to add a single or two mid span braces you can

 

[AcidOverride]

This is good to know thanks Would you fix the TileFix board down too or leave it sat on the timber so it can be free to contract and expand without effecting anything?

Thanks again for sharing, really do appreciate it.

 

[ShaunCorbs]

Manufacturers instructions some require glue some screws

I would always glue and screw your framing and ply

 

[AcidOverride]

Awesome, thanks for all the advise