Maintaning good water flow/pressure in house

[JimLoskot]

I'm having lead main replaced with 25mm MDPE in its place, Its then getting reduced to 15mm for the water meter.
The house is a victorian semi with attic conversion and will eventually have a cellar conversion and a toilet/bathroom on every floor (4).
What is the best way to ensure there is good water flow/pressure on all floors (especially at the top). I pressume there is no point in going back to 22mm after the water meter .
I enquired about the possibility of having a water meter on a 22mm pipe but was told they are all 15mm.
Apart from reducing the number of elbows/joints and keeping runs as short as possible and keeping to 15mm is there anything else that can be done to maintain good water flow throught the house.
Thanks in advance

Jim

 

[ChrisR]

You could use 22mm, the resistance is cumulative, not dependent only on the thinnest/
It's the valves which are very restrictive though. If you can use 22mm stopcocks etc instead of 15mm you'll make a diffreence. whether you'll notice that , depends...!
Loos aren't a serious flow, it's combi boilers and mains-supplied showers which care a lot more.
But, eg, 2.5 bar mains and 15mm pipe all through is s OK for a 30kW combi...
Have you measured your pressure and flow?

If the pressure's OK but the flow's poor, you could consider an accumulator, but that's a bit extreme.

 

[JimLoskot]

Haven't had the new main pipe connected yet so no point measuring the pressure or flow as hopefully it should go up a lot when its done.
Think we will probably be going for a system boiler (hopefully unvented if enought flow) rather than a combi.
Think I might try putting 22mm on the main branches to each floor and the boiler from the meter so hopefully will maintain good water flow throughout the house.
Also, the main stopcock I have to use when connected with the new supply is a 25mm to 15mm. would it maintain better flow to use a 25mm to 25mm stopcock and then a reducer onto 15mm for the meter?
Thanks