Lobster wrote:
Ian Stirling wrote:
Air goes through holes much, much easier than water, and will escape
hundreds of times faster than if filled by water.

Is it just about speed? Or is it likely that a system could be
watertight - ie perfectly serviceable in practice - but not actually
100% airtight?

Umm...
It depends.

For example, you'll likely never notice a leak that leaks 500ml/month,
but it'll cause a sealed central heating system to lose its pressure in
a few months.

If it's significantly below this - say 50ml/month, then if the boiler is
being serviced annually, you'll probably never know.

But, it may well leak very detectably with air.