UFH, can you have too much pipe?

[thompo]

Hi there

Planning on relaying floors with concrete and taking the oppertunity to install wet UFH.

Im playing about with CAD layouts for pipe etc and im wondering what effect having the pipe at closer centers means? Does it just heat the area up quicker? Other than cost of pipe is there any reason not to keep a tighter spacing throughout? Do you "have" to run the system at a lower flow temperature?

From the flow side i have spaced the pipe at 100mm in a serpentine (flow only) around high heat loss areas first (bay windows and door ways).

This then changes to a spiral shape with flow and return spaced at 200mm to even out the heat towards the middle of the rooms, with the final return exiting along an internal wall.
Pic inculded for clarity


Im thinking of keeping the pipe at 100mm throughout thinking if it does no harm, it leaves the option of using solar or a heat pump down the line to do the heating. Any reasons not to do this?



Thanks

Neil

Untitled

• thompo
• 31 Oct 2012
• 1

 

[Norcon]

When you tighten the spaces the recommended maximum loop length soon runs out.
Thats about 100 to 120m.

You've no dimensions on there that I can see so difficult to say if you're over the limit.

 

[ALEC1]

the more pipe the lower the temp you can run the supply...so no too much pipe is a good investment...

 

[Norcon]

Im thinking of keeping the pipe at 100mm throughout thinking if it does no harm, it leaves the option of using solar or a heat pump down the line to do the heating. Any reasons not to do this?

I think you have about 20sq/m in there so 100mm spacing @ 10m/m.
So 2 loops definately required.
Back to the drawing board.

 

[Agile]

All of this advice relkates to the diameter of the tube being used!

I once went to a boiler which had been connected to a DIY UFH installation under a hardwood floor!

He had used 90m of 10 mm copper pipe and wondered why there was virtually no heat getting into the UFH!

Tony

 

[thompo]

Cheers guys,

Im planning on 16mm PEX or PERT (havent decided, any real difference?) with Alu barrier. The floor will be 100mm slab, 100mm kingspan, UFH in 50mm Anhydrate flowing screed.

The room above is 10.8m² working out about 97m of pipe maintaining a 100mm spacing as much as possible. + i still have to add the final bits to the manifold (extra 6-12m) once i figure out how to route all the circuits to it! Our single biggest loop would be to heat a 17m² lounge with the total hall way coming about 20m² however this will probably be 2 loops to aid routing circuits.

May have to just keep the centers at 100mm in the high heat loss areas and work to looser centers towards the middle to keep the loops under 100m

 

[Agile]

That all sounds fine.

Whilst its a good idea to have closer spacing in high heat loss areas be aware that UFH is largely heating the air in the room and that moves around a little and will mostly all be at the same temperature.

Also having large furniture covering high heat loss areas could result in surface temperatures being higher than you might wish for the floor surface.

Tony

 

[thompo]

Sorry only getting back now,

Thats great, thanks very much for the info .

Would it be an idea then to have the periphery of the rooms and the centers at a higher density than the mid area where furniture is likely?

Or am i thinking about this far too much lol, lash it in at 150-200mm in a spiral and probably not notice much difference?

Cheers Neil