In article , Arthur
writes
I've just done most of the pipework up to
the new combi. There is just the connections to
the unit to complete.
Do I just use elbows to make that tight turn to meet
the combi connections?

Also, I haven't done the gas supply pipework yet so
this pipe would have to leapfrog a horizontal section of
the mains supply to the unit. Is this acceptable?

System connections (the big stuff), swept bends essential.
Feed & h/w connections swept bends recommended.
ie. not elbows.

Prob not what you wanted to hear . . .
--
fred