20mm black plastic water main to 22mm adapter needed?

[cypher007]

need advice on best way to connect to old plastic water main pipe. house was built in 1967 and has oddly 2 stop cocks. id like to go from the 20mm black plastic pipe to 22mm copper. but the plumber recons the internal is only about 15mm maybe. so hes gone from the plastic to 15mm copper then to 22mm which doesnt seem like it will help at all as surely its restricted by the 15mm section. does anyone know where i can get an adapter to go from the old water main to 22mm?

 

[jj4091]

22mm to 20mm reducer - Google Search

 

[Exedon]

Water service of that age is imperial sounds like 3/4 alkathene
If 15mm copper fits it internally its class C if bore is smaller it's class D.
If class C just use a short end of 15mm as a insert preferably put a flanoge on one end .
You can use 22mm compression fittings on 3/4 alkathene just swop the olives for 3/4 ones .

 

[polesapart]

21mm approx OD black alkathene will be 1/2" imperial nominal internal bore .
Roughly equivalent to15mm copper and 20mm OD modern blue poly.

 

[CountryFan]

Have a look on the stopcock, there could be some writing on which could indicate the size.

 

[cypher007]

thanks all. so essentially there was no point in upgrading the feed to our new unvented and the HW run to 22mm as the 4 inch bit of 15mm thats on the main plastic will limit the flow?

 

[Exedon]

Your flow will be limited by the alkathene which is roughly 15mm internal.
Unless current access for changing pipework to 22mm is easy and you want to future proof for a possible water service upgrade?