"olo" wrote in message
oups.com...
Hi folks,

need your advice on pipe size - what would you recommend (15mm or
22mm) as a supply (cold) to and flow (hot) from combi boiler to taps?
Boiler can produce 14 ltrs/min so one would think that 15mm pipe is
enough. However there are opinions that 22mm is preferred because
boiler will get priority in getting cold water.

Have a dedicated pipe from the stoptap to the combi with nothing teed off
except the cold to the showers just before the combi. Also have the shower
hot direct from the combi, and again a dedicated supply. 22mm would be
better for the reasons you stated, however 15mm should be fine if a
dedicated cold feed.