Replacing water pipes, 15mm to 22mm to 15 and back again

[cjbooth]

Hi,

In the process of adding a new bathroom upstairs and have exposed all of the old piping around the kitchen where the combi is. What I have is a 15mm mains feed to the combi this is T'ed off for the cold water, hot then comes out of the combi on 15mm.

This is where is gets interesting, both hot and cold, go from 15mm to 22mm on the way to the bathroom, then back to 15mm to all of the feeds.

The 22mm section is about 8m long, shower downstairs take some time to warm up, i'm guessing this is because of the distance and pipe size.

Would it be better to just replace all of the pipe with 15mm?

Thanks

 

[bengasman]

If it is all in good condition, leave it; replacing will only bring very marginal quicker response for dhw

 

[Bahco]

Would it be better to just replace all of the pipe with 15mm?

Yes, I would remove ALL the 22mm piping supplying hit and cold pipes.