15mm or 22mm pipe

[jddevel]

I`m in the process of installing the plumbing to quite a big new house (240sq mtrs and self build) and would like views on internal pipe sizes. The house has under floor heating upstairs and down. Four ensuite showers one with bath. Vented oil boiler (may change later to solid fuel-pellets but euro has currently put that idea on hold). Obviously kitchen appliances and downstairs WC. It will also use vented thermal store so providing mains pressure hot water.
The mains supply as stated by the water authority is at least 10bar and may be 12 so they certainely recommend a pressure reducing valve at stopcock.
Besides wanting to know whether 15mm pipe will be adequate through out the property what would be the advice on setting the reducing valve pressure to?
Thanks in anticipation.

 

[swbjackson]

With the number of outlets you're considering 15mm will be inadequate. I would look at setting a PRV to around 5 bar unless any appliances specify a lower setting.

With water pressures that high make sure that all of your pipework is properly clipped or you will end up with horrendous water hammer problems.

Mike

 

[jddevel]

Thanks Mike thought as much. Is there a "rule of thumb" as to the extent of 22mm pipe I should use. Would for example 22mm pipe from supply in to house to 50% of the building with 15mm spurs to individual take off points or would you suggest taking the 22m to the end of the service needs?
Thanks again. Regards JD

 

[superdupergasman]

as you said...22mm most of the way where there are multiple service needs, once down to one supply you could run 15mm. and plenty pipe clips!!

 

[bengasman]

at the very least 25 mm in, though bigger would be better and then a split into 2 x 22 with only the final parts to individual taps in 15

 

[jddevel]

Thanks for all your good advice- its appreciated.
Regards JD