On 28/10/2020 19:07, David wrote:
On Tue, 27 Oct 2020 18:38:30 +0000, Tim Lamb wrote:

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

As an aside when our new Worcester Bosch combi boiler was fitted I read
the installation manual.

If there were more than a certain number of radiators it required an
additional expansion vessel to be fitted (beyond the one which came inside
the boiler).

I presume because the extra volume of water caused more expansion when
heated.

The plumber had never heard of this before.
[Was also indecently amused that anyone would bother to read the manual.]

Anyway, no idea about the recommended location.
It was a while back.

I assume that the pressure difference between pump out and return might
affect the expansion vessel? Pop the release valve if there is one?

Cheers



Dave R


No relief valve, relies on the one in the boiler. Difficult to
over-pressurise anyway until the diaphragm fails. Probably the schraeder
valve that is the weak link.