Rising main, should I convert 15mm to 22mm?

[GreyBana]

I'm half way through a major DIY project and have a fair amount of plumbing to do (I've got a whole new floor of the house to plumb, central heating & hot/cold water). I took at look at the main feed into the house and it looks like it comes up in plastic blue pipe, I'd guess around 25mm, into a stop cock that immediately reduces it down to 15mm copper.

I'm thinking that I should replace the stop cock and pipe with 22mm copper, so the whole house has good flow. Downstairs would mostly be copper and upstairs would be plastic (where I won't be able to feed long lengths of copper through the floor joists). I'd then T off with 15mm for taps/showers/baths, but 22mm would be the main "trunk" throughout the house.

First time doing something like this, so I wanted to know if this is a good idea or if there are reasons not to do this that I don't know of?

Thanks in advance.

 

[cross thread]

What pressure/ flow rate have you on the mains? But certainly no down side of running 22

 

[GreyBana]

As of right now, we're getting about 5.1L a minute on a tap very close to the main feed in. I don't know what's good/bad though and I assume a pressure gauge would be needed to get the pressure, unless there's a MacGyver-type way to find out.

Thanks for confirming though, good to have a bit of reassurance. Even if it means that I'm future proofing if the house.

 

[Dereekoo]

Standard minimum acceptable value for flow at edge of property stop valve is 9l/ min, depending on where your tap is on the system your supply seems to be at the low end. Ask water company to confirm flow and pressure at their boundary box, pressure should be at least 7metres head.i.e. enough to push flow into your header tank.

 

[GreyBana]

I've just measured again from a different tap (much further from the main feed) and I am actually getting 9.6L/min there. My Kitchen tap is a bit naff, so that could well be the issue there. Apologies for the red-herring.

At what flow rate does 15mm copper start to become the bottleneck and make 22mm worth having?

 

[Dereekoo]

All depends on what service pressure/available flow/length of pipework to be replaced/ what flow is acceptable. My supply is more than adequate with house approx 15m from boundary box and fed by 1/2 inch copper pipe. Normal header tank storage no combi boiler.

 

[JohnD]

If you are doing plumbing work in the house, this is a good time to do it.

Water flow will be quieter and you will get a better shower when one day you go to a combi or an unvented cylinder.

Fit the larger stopcock or it will restrict flow.

 

[GreyBana]

Thanks John. Take the decision away from me, that's what I need!