I have a Britony Combi 80 - made by Chaffoteaux at Maury.

Well I noticed the water pressure was slowly going down, so I refilled as normal - via a metal hose under the unit.
Then I decided to bleed the rads (upstairs had more air than water in them air!), then I obviously saw the water pressure drop rapidly and refilled until it behaved as normal...

Since then (a week ago now) I have seen the pressure drop to zero, within 2 days.
The is no *obvious* leak, there have been no changes, except I have bled the rads.

Am I missing something here?

We have had to to have the mechanical peice (I know not the name) that switches between service to the rads OR the hot water replaced *every* year for the last 4 years!
Yes the system is only 4 years old!

Thanks,
HotShot