Connecting radiators to UFH Manifold?

[valmiki]

Hello everyone, I wasn't sure whether to post this in the UFH sub forum or here, so feel free to move this if you see fit.

 

I currently have UFH installed through the house, on 3 floors. Ground floor (screed), first and second floors using aluminium spreader plates. The house was renovated 2018.

 

The ground floor works pretty well and I don't really have an issue with the UFH per se, the system itself works as intended (especially after Nick on here fitted a buffer tank a while back).

 

The upstairs floors however are a different matter - the spreader plates are fitted on joists, on top is 22mm wyrock, 2mm underlay and then 14mm engineered wood flooring. Beneath the spreader plates is rock wool. As you can imagine this doesn't it an ideal way to dissipate heat quickly into the rooms, whoever thought encasing the pipes in wood would ever work well (that would be my builder with me giving the gormless nod lol). It just doesn't let enough heat out to warm the bedrooms. I've nursed it through 3 winters and I think I now need to get this sorted one way or another.

 

Here's the attic floor:

Each room has its own thermostat and the attic floor being a new addition is pretty well insulated with 200mm celotex in the rafters.

 

The idea I had in mind is to first work on the attic floor, which is devoid of furniture at the moment. I was thinking lift up the wood floor, then the 22mm deck. Remove the pipes and spreader plates. Then run pipes (barrier?) to connect radiators to the 4 port manifold:

 

 

Before I waste anyone's time - Is this feasible? In an ideal world I'd like to have the radiators connected point to point rather than on a ring - I'm not fussed either way but I would like to retain the ability to heat the floor as one zone independently with it's own thermostat from the rest of the house. I'd also like to connect 5 small/medium size  radiators (1 bathroom, 1 wardrobe, 2 bedroom, 1 landing). Having done the heat calcs using an online calculator this looks acceptable to provide enough heat in the winter.

 

First issue I can see is that the manifold mixer valve only goes up to approx 65C - and I can't really oversize the radiators as I don't have that much wall space to hang the radiators on. I may need to replace the manifold with something else? Am I on a hiding to nothing (!)

 

Penny for your collective thoughts, and thanks for your insight 

 

valmiki

 

 

 

 

Edited February 1, 2023 by valmiki

[HughF]

65 deg will be fine, but you’d be a lot better to remove the pump, hook the flow and return up to the manifolds, then throw the rads on the end of the pipe loops. That way your boiler weather/load compensation has control over the flow temp.

 

you can use the existing 16mm pipe, just transition to copper before going into the rad valve.

[valmiki]

11 hours ago, HughF said:

65 deg will be fine, but you’d be a lot better to remove the pump, hook the flow and return up to the manifolds, then throw the rads on the end of the pipe loops. That way your boiler weather/load compensation has control over the flow temp.

 

you can use the existing 16mm pipe, just transition to copper before going into the rad valve.

 

👍 

 

Did you mean remove the mixer valve rather than the pump?

[Nickfromwales]

Ola.

Have you worked out how much more ( additional ) heat you actually need up there to get it to an acceptable level? Could adding skirting heating get you there? Would save a bunch of extra work.

 

If you migrate to rads then could just ditch everything back to the 2x 22mm flow and return and connect the rads directly using only TRV's on each rad for control.

 

If you wish to retain the UFH controller and stats ( do you have 1 stat per room / space up there? ) then you'd simply ditch the TMV on the manifold and install a TRV on each rad.

20 minutes ago, valmiki said:

Did you mean remove the mixer valve rather than the pump?

 

Yes, that's correct.

 

The TRV's would still open up fully to get to their respective set points, and only reduce the flow rate as the room / space is arriving at / has achieved the set temp.

 

Just pipe each rad back to each respective manifold port and then job done.

[Rich123]

Hi , I think ideally you would connect to the primary pipe supplying the manifold , assuming that it’s supplied from a boiler , as the temperature will be higher .

if you connect the radiator to the underfloor you would need to increase the size to compensate for the lower temperature, but it can be done . Approximately double the size radiator if off ufloor.

[Nickfromwales]

2 hours ago, Rich123 said:

Hi , I think ideally you would connect to the primary pipe supplying the manifold , assuming that it’s supplied from a boiler , as the temperature will be higher .

if you connect the radiator to the underfloor you would need to increase the size to compensate for the lower temperature, but it can be done . Approximately double the size radiator if off ufloor.

Nope, you'd just remove the TMV from the manifold so it gets 'full-range' heat from the boiler flow.

[Nickfromwales]

Actually, just zoomed in. The TMV goes to 60^oC so as this is the attic, and heat rises, the TMV could probably stay in for a trial run ( with it fully open ).

[valmiki]

Thanks Nick and everyone for your replies, much appreciated.

 

I've got something to go on for now.

[Handers]

Manifolds include auto-air vents... which work, because they are always situated higher up than the UFH loops built into the screed.

However, when you start to use them with radiators, that might not be the case. So I'm curious, did you position it higher up the wall to try and keep the vent above the level of the radiators, or do you just bleed any air in the system using the radiators themselves (as you would with any standard sealed system). I guess the manifold vent probably just becomes redundant, unless you can fix it higher up the wall.

 

I'm about to undertake the same approach in my build, but am undecided on this particular point. I'll probably keep it low and just rely on occasional radiator bleeds.

[valmiki]

Hi, I haven't been able to carry out the work yet, and now it's summer so it's on the back burner (!) radiator bleeds probably best in your case

 

On 15/05/2023 at 10:20, Handers said:

Manifolds include auto-air vents... which work, because they are always situated higher up than the UFH loops built into the screed.

However, when you start to use them with radiators, that might not be the case. So I'm curious, did you position it higher up the wall to try and keep the vent above the level of the radiators, or do you just bleed any air in the system using the radiators themselves (as you would with any standard sealed system). I guess the manifold vent probably just becomes redundant, unless you can fix it higher up the wall.

 

I'm about to undertake the same approach in my build, but am undecided on this particular point. I'll probably keep it low and just rely on occasional radiator bleeds.