On 09/03/2016 20:38, Tim Watts wrote:

That's what I'd like. I have my central distribution pipework in 22mm,
with separate drops in 15mm to the kitchen, bathroom, shower room (when
done) and outside. That's a happy coincidence of having the under stair
cupboard (actually a big walk in cupboard) dead centre and between the
boiler site and everything else.

Sounds very similar to my own layout.
The "airing cupboard" was originally a boiler cupboard converted later
in life to a hot water cylinder cupboard and wall boiler which I ripped
out and it now houses the UFH maifold and acts as a riser from
downstairs to upstairs.

22mm pipes on everything then spurred off in 15mm to kitchen, shower
room etc


I am also including flow limiting valves (BES, they take an insertable
cartridge available in 8 or so flow rates) to balance the system - so
running a bath will not starve everything else - and so that a tap on
full in a small basin does not a) blow back in your face; b) defeat the
basin overflow. Rather nifty little valves that include a full bore
isolator too.

So far I've found that the 22mm - 15mm serves to adequately balance the
system without any problem although we don't currently have a main
bathroom as it was gutted 3 or 4 years ago and is on the "to-do" list.

Also have main 22mm cold water feed running through water softener
before it hits the boiler so cold/hot are all soft.

As part of the current extension project the builders destroyed the old
black water-mains from the street as it ran along the foundation route
so I re-ran the pipe from the street meter in 32mm to the boiler side of
the house rather than the garage which cut down the meter to house
distance by a good 15 to 20m.

Another un-planned upgrade ticked off the list.