On 21/08/2020 09:09, Rob Graham wrote:
I'm replacing my 25 year old oil Camray boiler with a Grants condensing one. The return pipe (22mmm) particularly will now go from close to the bottom of the housing to the top involving 3 right angle bends over an ~800mm pipe run .

Could I do this in plastic piping to ease all this contortion?

22mm plastic is not very flexible, and (if visibly) snakey stuff doesn't
look very nice. As other poster said, they may recommend copper for a
certain distance. Do as much of the wiggly stuff as possible in copper
to keep the plastic bit as straight as possible.