backfilling via vent pipe (water level) .... ??

[londonboy123]

here's one - when backfilling a system (to get air out via the vent) - after doing this how does the level of water in the vent pipe level out again to its original level?!! the normal level is supposed to be the same as that of the level of water in the cold water tank .... how is this achieved ?? a science question maybe??

 

[JohnD]

I wonder if you are talking about an open-vented central heating system, or the hot taps?

 

[Goldspoon]

Water leaks out of overflow until everything balances?

 

[londonboy123]

as a matter of interest, on both the cwcs and f & e vent pipes .....

maybe as mtnioned above water leaks out overflow until the normal amount of dry head is achieved again?!