UFH what determines pipe centres ?

[Canski]

I keep getting conflicting answers from different UFH companies about pipe centres. Some say 150 and some 200 mm centres. What is the science behind this ? It will be a 75 mm cemfloor slab on insulated beam and block with a u value of 0.12. 

[JohnMo]

I went my own way and did 300mm.

 

Pipe and mean flow temp determine the output W/m2 (and floor covering).

 

The lower the W/m2 required the less the pipe centers have an effect on the mean temp required.

 

So at 20W/m2 and 100mm centers the mean flow is 31, while at 300mm the mean flow is 33.

 

 

 

[Iceverge]

I assume from this graph that it's possible for some members to run at flow temps in the 20's. 

 

At say 10w/m2 and 150mm spacing then about 25-28deg flow temps look possible. That would result in a superb COP for an ASHP.