Replacing 15mm copper CH system with 10mm PB barrier pipe. Is this the done thing now?

[EddieJT]

Got a CH leak somewhere under the floor of a studio flat (boiler is losing pressure, but holds when CH flow and return are isolated).

It's currently 15mm copper, but I'm loathed to start lifting floors looking for a leak; it's only 3 radiators so thinking of surface mounting with new 10mm PB barrier pipe. Is this a thing now? Do people instead of the old 15mm copper, now do 10mm plastic push fit (Hep20 fittings and PB barrier pipe)?

Will I have flow problems going down from 15 to 10mm (bearing in mind this is only 3 rads, 2 of which are small).

What about connecting to the 22mm boiler flow and return? Any reason why I can't cut in a 22mmx10x10 tee?

And what's more flexible, from Screwfix/Toolstation's offerings; the Speedfit "layflat", PB barrier or Hep20?

 

[jj4091]

edited

 

[Jurassicspark]

Put the run in with 22mm then tee of to each rad in 15mmyoull get better flow plus the system can be flushed if you ever need to

 

[EddieJT]

Since this will be surface mounted (just above skirting board) I'd rather do runs in the less conspicuous 10mm. Needs to get through one wall too, which will be easier with the 10mm.

 

[Exedon]

Unless you intend boxing pipes in 10mm plastic will look a dog! huge amount of expansion when hot..
That's assumes rads are small enough to work on 10mm
If you really must use 10mm go for copper.

 

[EddieJT]

You mean the pipes will bow between clips when hot?

 

[Exedon]

Sag is more the word! loops hanging down between clips.

 

[Madrab]

surface mounting with new 10mm PB barrier pipe. Is this a thing now?

Nope
Don't get me wrong a smaller system with smaller (type 11) rads will run quite happily on 10mm and it's usually done for ease of use, price and speed of install but it isn't really a good idea on a med/larger sized system with med/larger sized rads.

 

[Jake2021]

Personally I wouldn’t use 10mm poly, they use it on new builds and it causes more issues then anything. 15mm will give you better flow and is more stable , poly tends to Ben especially the hot water v cold no matter how matter how many clips you have… the best solution would be to find the leak it’s prob from a soldered joint.

If you must surface mount them I’d change the skirting and do it because you wouldn’t be happy surface mounting the pipes it will bug you in the future.
Regards
Jake

 

[gas112]

You can't run 3 rads off 10mm they each need a separate 10 mm feed.

 

[Notch7]

Will I have flow problems going down from 15 to 10mm (bearing in mind this is only 3 rads, 2 of which are small)

The bore size of 15mm copper is 13.6mm
The bore size of 10mm plastic is around 6.8mm and smaller than that where the inserts are

I though 10mm systems have a different layout using a manifold, so the 10mm pipes only feeds individual rads - could be wrong on that though

 

[Jake2021]

Notch you are correct