In midst or reasonable sized extension of living accomodation
including extensions to CH and H&C water.

Used 15mm Hep, 22mm Hep and some "toolstation" 22mm plastic (all
barrier) - need some fittings to suit a few awkward connects from 22
to 15 (reducing tees) - they are avaiable in Speedfit but not Hep or
Polyplumb -

QUESTION when joining 2 different makes of plastic pipe at a certain
(possibly 3rd party brand) fitting - whose pipe inserts do you use -
the pipe manufacturers? or the fitting manufacturers? or doesn't it
matter? (and why please!)

thanks in advance

Jim