In article ,
Dave writes:
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).

The best way is to feed the pipe through them as you install it,
so you don't have to split the foam sleeve afterwards. If you
do split it, it has a tendancy over time to open up at the split.
You can get some plastic staple like things you push in along the
split to stop it doing this, but I don't know how effective they
are. It does follow swept bends OK (at least when you don't split
it). I tended to cut the pieces slightly too long so that it is
in compression when installed. I see lots of installations where
it's shrunk leaving bits of pipe exposed, and mine hasn't done
this (yet, anyway).

For central heating, I believe it is only required to insulate
where the pipework passes through unheated areas, like under a
suspended ground floor, but not for example between a floor and
ceiling of two heated areas. I also insulated it where any
electricity cables were in close proximity, but that was more
to protect the cables from heat. This can also be a good idea
where it's near a cold water supply pipe, so you don't turn on
the cold tap and find it runs warm for several seconds.
Part L also requires insulation of the pipes connecting to the
hot water cylinder, if you have one.

I bought my insulation from Wickes who had it going cheap at the
time as part of one of the energy saving initiatives. I believe
the foam you need is the type with the wall thickness same as the
pipe diameter. There is some much thicker stuff too, but thats
rather more for preventing outdoor and loft cold water pipes
freezing in winter. You might consider that for the pipework in
your garage if it's not heated, but ISTR it was much more expensive.

--
Andrew Gabriel