Pipe sizing to and from UFH manifold

[OldSpot]

I'm trying to find information on sizing to and from an UFH manifold. Does any one know of a source please?

The run is approx. 12m and LoopCad says ~ 15l/min needed in total for the UFH loops.

 

Many thanks.

[MikeGrahamT21]

22mm minimum, will give you 36l/min.

 

15mm only just scrapes in at 18l/min

[OldSpot]

Cheers Mike

[PeterW]

Heat source ..? Buffer ..? 
 

Minimum 22mm, depending on the other items you may need 28mm 

[OldSpot]

@PeterW Hi Peter,

 

Heat source is an oil (system) boiler and I'm looking at whether/how to use a buffer as I'm concerned about the boiler cycling too much.

 

On the issue of buffers.................I'm actually just going through that now.

My current thinking is to use a 150/200l indirect tank to buffer (LoodCad suggests UFH is about 11kW, which correlates reasonably well with my heatloss calcs). It will only serve the UFH.

I'm getting a little lost on whether the tank needs to be vented or can be sealed.

The coil would be from the boiler but would the UFH side then be classified as unvented (due to tank size) and come under G3 if it was a sealed system?

 

I could alternatively fit a small F&E tank directly above the tank if needed

 

[PeterW]

100 litre buffer will be fine - don’t bother with a coil, just make sure there is a mag filter on the way back to the boiler. 

[OldSpot]

Thanks Peter,

 

Any reason a simply stainless steel direct cylinder (like this) can't be fitted?

[PeterW]

Anything like that will do. 900x400 for £169 delivered here

 

https://www.cylinders2go.co.uk/shop/vented-cylinders/direct-vented-copper-cylinders/900-x-400-direct-copper-cylinder/