"Reestit Mutton" wrote in message
...
....
Just to recap, I have the following:

22mm plastic pipe with insert
15mm plastic pipe with insert
22mm elbow joint
22x15mm internal reducer

I'm not sure those reducers are designed for use with plastic pipe.

(all purchased from B&Q if that has any bearing on teh situation)...

I suggest going to a proper plumbers' supplier, telling the bloke behind the
counter what you want to do and asking him to supply you what you need.

Colin Bignell