B A R R Y writes:
Andy Dingley wrote:

In general, no. However a machine that has a slow leak down somewhere
and is going to be switched off for long enough to empty itself is
usually best vented deliberately rather than being left to do it
inevitably itself (or just fix the leak!)

Why is that?

It's like a Ni-cad. Let it get too empty and you can't fill it again.

scott.

(That there's a joke, son.)