On Tue, 27 Oct 2020 21:20:59 +0000, newshound wrote:

I am considering fitting an additional expansion vessel to our
heating
system. Advice specifies boiler return pipe location. Why?

It's that bit cooler so less wear on the diaphragm.

But it is a dead leg, so not much conduction unless it is very short.

Well it's dead in that it goes nowhere but there is still the
flow/return due to the expansion of the water from cold to hot and
back. I think that expansion is about 1 l per 100 l 10 to 70 C,
guesstimate that's a metre or two of 15 mm pipe.

--
Cheers
Dave.