Pipe sizes in new mains pressure water system

[spada01]

I'm running 25mm MDPE upto the stop cock. I'm then planning to go to 22mm copper and split in three ways - 15mm plastic to kitchen sink, another 15mm split to combi then 22mm to feed two bathrooms and to split into 15mm at each.

Does this sound sensible?

 

[bengasman]

Do you have a combi or (un)vented cylinder?

 

[spada01]

Combi. Flow rate about 14l/min

 

[bengasman]

22 to bath mixers, all else in 15, mains to boiler should have dedicated 15 from the 22 ( nothing tee-ed off ).

 

[mysteryman]

There is no point in fitting 22mm hot downstream of the boiler when the cold feed to it is only 15mm. Do all this in 15mm and keep the pipe volume down.