Dave wrote:
I've finally finished installing the new heating and DHW system (with
some help) but now I need to insulate all the pipework. Most of the
downstairs ceilings are down so I can get to the pipes easily; the
boiler, cylinder, zone valves and DHW circulation pump are all in the
back of the garage.
What's the best and most economical way to insulate the pipes?
I've seen the lengths of semi-rigid foam sleeve in the sheds but these
ar not going to be any good on the bends (and are not cheap).

You can get a sort of metallised bubble wrap in about 50mm width for
pipe lagging, from the usual online suspects, but it's a bit pricey.
However Wickes (and no doubt others) do the same(?) stuff in about 600mm
width which would probably be cheaper and possibly easier to use.