32mm vs 25mm MDPE query.

[Ant1]

Hi all,

I am going to replace the lead pipe coming from the street to my home (Scottish Water will be doing the connection).

I have most of the details from Scottish Water though I have a few questions regarding MDPE as I am mainly familiar with 22mm and 15mm piping.

My questions are:

1) I understand using 32mm vs 25mm MDPE will not make much difference regarding the pressure, but should help regarding the flow rate.
Considering the water pipe going to my combi boiler is a 15mm pipe (to produce hot water), would it make a difference using 32mm vs 25mm when opening the hot water tap on 2 different sinks? (I am wondering if this would help increasing the flow of hot water or I am over engineering things)

Note that the MDPE run from the street to the house is 10 metres.

2) If I run a 32mm MDPE pipe from the street to my house, do I have to use a 32mm stopcock first and then reduce to 22mm? Or can I reduce first reduce to 22mm and connect a stopcock after?

3) Is a check valve required before the stopcock?

4) 32mm to 22mm stopcock does not seem common, what is the most suitable set-up? (2 bathrooms, with main Scottish Water stopcock 10 metres away)

Thanks a lot!

 

[Exedon]

Increasing size will have zero effect on pressure but it will help maximise flow.
For the cost difference if you want to do it why not. Certainly if this was site work 25mm would be used.
When you have bring service into property above ground 32mm x 22mm reducer then stop tap
If local regulations ask for a check valve that goes after stop tap.

 

[Ant1]

Thanks, I am aware than 32mm will help maximise flow of cold water in my property (which is mainly in 22mm coper). My main query is regarding the flow of the hot water coming from the combi boiler, as it is 15mm at that point. Would 32mm MDPE also help maximising the flow of hot water in my case?

 

[Exedon]

Because of quiet small distance involved gains may be minimal but every little helps!

 

[denso13]

Would 32mm MDPE also help maximising the flow of hot water in my case?

With a combi, the faster the hot water flows, the cooler it will be. To keep the same temperature you'll need to keep the same flow rate.

 

[Madrab]

Thanks, I am aware than 32mm will help maximise flow of cold water in my property (which is mainly in 22mm coper). My main query is regarding the flow of the hot water coming from the combi boiler, as it is 15mm at that point. Would 32mm MDPE also help maximising the flow of hot water in my case?

Depends on the boiler. Some boilers are flow limited to ensure they meet the specified ouput in L/Min. Others aren't and as suggested the flow can increase in line with the mains but then output temp decreases. It also depends on what your mains is delvering to the boiler at the moment and what the maximum rate your boiler can output.