Converting house into flats, do I need 50mm water pipe?

[PropertyOwner1682]

Hello,

I am converting a house into 11 flats run by electric only.

Each flat will have a kitchen and a mini electric boiler to power the sink and the shower.

We were told by a plumber that we would require a 50mm diameter supply from the water board, this is quoted at £11,000.

We have also been told that the main we will be connecting to is 3 bar.


My question is...

Is a 50mm diameter supply really required? (we do not know size, flow or pressure of current supply).


Any help is most appreciated, obviously if we need a larger pipe then that's fine but I'm just curious as to whether the advice we have been given is correct or whether there are better and cheaper alternatives.

Also how best I could find out the current size, flow and pressure?

 

[oldbutnotdead]

50mm internal diameter gives each flat a supply pipe equivalent to about 7mm internal diameter which is not generous. No idea if you are allowed to apply diversity reductions on water supply, £11k sounds a bit excessive.
Local water pressure- ask you local water provider, they can test at the street main.
Good luck with the electricity board- 11 flats at 60A each will need a chunky incomer. How are you heating the flats- if that's electric as well then ooof, if its gas then why aren't you using gas to heat the water?

EDIT Either gas or electric, you may well find it more cost-effective to have one large boiler and heat meters for each flat (yes they are a thing). Drawback- your tenants won't be eligible for any support from current or future government energy cost reduction initiatives.

 

[gas112]

11 flats on electric / the electric will need up grading as well

 

[Justin Passing]

7mm????

Pipe resistance is proportional to something like 1/(d^4.4) depending on several things
So going from 22mm id to 46mm id will give you around 20x the flow - theoretically.
It can work out ^2.5 iirc.
Talk to your water supplier about their guaranteed flow and pressure, it might be horrifyingly low at peak demand.
There are nomographs which are based of measurements rather than calculations.
This is an imperial one

 

[robinbanks]

£11k sounds a bit excessive.

Drop in the ocean of the profits generated by selling 11 residential units