On 27/10/2020 22:00, T i m wrote:
On Tue, 27 Oct 2020 20:20:51 +0000, newshound
wrote:

On 27/10/2020 19:38, T i m 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?

Because you wouldn't want to pump pushing water *towards* the tank?

Cheers, T i m

I'd say rather that any pump noise at vane passing frequencies will be
effectively damped after going all the way around the system.

Ah, I was thinking 'expansion tank' not 'vessel'. Not got any CGH
here, let alone a sealed system. ;-)

But TBH I don't think it would matter much.

No, I agree, especially in the vessel case.

There might be some 'best practice' reasons to do it one way or some
technical reason to do it so though.

One bit of advice, though. Include a service valve between the system
and the tank, and also a drain cock on the tank side.

+1

Then it is very
easy to check the tank pressure in the future.

An advantage of a vented system, you can peer in the top of the
expansion tank?

Just remember to open the
valve afterwards.

Depending on why Tim thinks he needs a second expansion vessel, it may
not make any noticeable difference?

(I have a lever type ball valve on mine so that its
setting is always immediately obvious).

When I was doing all the plumbing here 40 years ago they typically
recommended gate valves (low pressure) and conventional stopcocks
(mains pressure), I'm not sure ball valves were used much outside
washing machine attachments?

Cheers, T i m

I reckon the modern small ball valves are pretty good, and not silly
money. You can get full bore ones that are only slightly larger than the
standard service valves. I also favour the ones with a proper lever on
them. I have an extra couple for "easy access" on the gas and water
mains. You can even train wives and children how to use them.