"Dave Plowman (News)" wrote in message
...
In article ,
Tony Bryer wrote:
I thought that one of the features of sealed systems was that - in
the event of a leak - they should only spill a couple of litres of
water before running out of pressure. Is this not so?

A finite amount of water: initially the volume which the expansion
vessel has taken up when pressurising the system and then the rest of
the water in the system above the hole - either a steady drip, or at a
greater rate if an AAV in the boiler or elsewhere is letting air in.
But at some point it will stop whilst with a gravity system and header
tank supply not turned off the water will flow indefinitely.

True it will, but a well designed 'open' system will in fact 'consume'
very very little water,

snip more senile drivel

The point was in case of a leak. If away fro 4 weeks and the sealed system
springs one, only the water in that part of the system will leak, with an
open vent system is will be a continuous water fall.

Boy some people are dumb.