Brand new bathroom plumbing

[razorrobo]

I am currenty installing a new bathroom upstairs (curently only one downstairs which will be converted to just a toilet and sink when upstairs is finished).

Is it standard practice to run a 22mm supply pipe around the new bathroom and tee off with 15mm pipes for bath/ toilet sink for both hot and cold? water pressure is good. Also have been told mixed stories about isolation valves (the screw types) some restrict the CSA of the pipe as when they are open they are about 2/3 of the normal diameter, does this matter? Thanks

 

[mikej2005]

Is it standard practice to run a 22mm supply pipe around the new bathroom and tee off with 15mm pipes for bath/ toilet sink for both hot and cold? water pressure is good.

Hot water is often supplied from a (vented) cylinder in 22mm (staying with 22mm for the hot bath tap and dropping to 15mm for a sink, in my experience at least) and usually 15mm all round the house in combi systems.

I've personally never seen mains cold in anything other than 15mm, but I'm a DIYer rather than a pro, so some of those guys may know better. (One exception to this is often the feed for an unvented cylinder)