That would negate the point of him doing it. Its the return side but still
might be very hot I guess. I'm a bit old school having had many friends
where modern installations using plastic have had leaks and strange effects
due to plastic pliability mixed with the metal used for other parts of
their systems.
The more I read here about CH systems the less inclined I am to have one!
Brian

--
--
This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...

Blind user, so no pictures please
Note this Signature is meaningless.!
"newshound" wrote in message
...
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.