Water Meter Restricting Flow? My Brain Hurts

Hi Chaps,

Our water comes in from the main in what seems to be a 22mm black plastic pipe that sprouts up through the concrete floor slab.

From this it then goes into a stopcock where it gets reduced to 15mm, goes through the water meter and then back up to 22mm.

My question is this, does the 15mm restrict the flow of the 22mm around the house to the same as if it was all plumbed in 15mm?

this may sound like a simple question but then I thought is the flow more to do with the pressure as opposed to the pipe diameter?

Then I went cross eyed.

All advice is welcome - the reason I ask is because I want to replumb some of the house, will be using 22mm but want to know if it is necessary to get the meter changed, or to just do the lot in 15mm.

thanks in advance

The Black plastic pipe is "Alkathene" which has a 1/2" (15mm) bore.
The incoming supply is therefore only 15mm.

Many people find it difficult to visualise how water ( or gases ) flow through different part of pipes when they are of different diameters.

The reason is that the flow velocity increases through narrow pipes and slows in wide ones.

Tony

Terrywookfit said:

The Black plastic pipe is "Alkathene" which has a 1/2" (15mm) bore.
The incoming supply is therefore only 15mm.

Click to expand...

That simplifies things for me then!

Agile said:

Many people find it difficult to visualise how water ( or gases ) flow through different part of pipes when they are of different diameters.

The reason is that the flow velocity increases through narrow pipes and slows in wide ones.

Tony

Click to expand...

Thanks, we seem to have really stong water pressure anyway so hopfully it wont be too much of a restriction with our 15mm pipes.

That will depend on the length of 1/2" pipe and what flow rate you hope to achieve.

There is the dynamic flow rate that is the most relevant to most properties which use a combi boiler or unvented cylinder.

Ideally a dynamic flow rate of over 12 litres per minute @ 1.0 bar dynamic pressure would be the minimum.

Tony