Pipe sizes CH flow and return

[bbasmdc]

My six bed house (lotsa kids) has a seperate CH bolier (about 60k) with 28mm flow pipes splitting into 2x22mm one feeding downstairs the other upstairs. My builder is doing some structural work which meant him moving the boiler and has made it a pressurised system. Because of piping runs he has reduced the 22mm downstairs feed/return pipes to 15mm for about 5m before joining them back to the 22mm pipe. He says that because its now pressurised (about 1.5 Bar) that it will make no difference.
Anyone have any learned opinions about this please?

 

[Deleted member 105431]

bad idea, I wouldn't want that in my house. Cutting corners is not the answer and pressurising it doesn't change flow thru bores of pipework.

 

[powell30]

Rubbish. Pressurising means nothing. It's flow and resistance that count. That said i don't see a problem but you may have to balence the rads to ensure a good flow.....and he may have already done this

 

[bbasmdc]

Thank you both for your replies. Not sure whether to tell the builder to undo some of his work to run all 22mm or not.

Maybe I will sleep on it.
Regards

 

[andytheplumber]