Aladdin self-bleeding radiator valves

Why does the highest rad collect *all* the air, if that's really true (not in my system)? What happens to air that rises to the top of another radiator, how does it move to the highest rad?

MBQ

It is often the case, IME, that there is one radiator (very often one of the highest) that collects the bulk of the air after refilling.

Obviously air that has found its way to another radiator stays put.

When you think about how the pipe work is arranged very often the T joints from 22 to 15 are such that the 15 emerges from the side or underneath the

Perhaps when the system was refilled they all collected air to some extent but at the moment this one is the only one with a problem. I'm not sure why it's getting air in as it's some months since we refilled.

I do think it being the highest radiator contributes in some way: water finding its own level and all that.

I have the Aladdin valves on the other rads and so if I am getting air in those other rads these valves are venting it automatically without me knowing. It's just this one particular valve that isn't working.

Imagine air travelling along in a pipe as a bubble - it could end up in almost any radiator as the flow would carry it.

Exactly. And once trapped at the top of a rad, it doesn't magically re- dissolve and move to another does it? So why the perpetuated myth that it'a always the highest rad will collect air?

MBQ