WHAT WOULD HAVE CAUSED AN AIR LOCK IN MY WATER SYSTEM?

As you've solved it I wouldn't go to the expense of a plumber. My friend had problems with air lock in his system and when I checked the attic cold water tank it was empty and the ball valve had stuck in closed position so no water being let in. As soon as I freed it and cleaned off lime deposit that was holding it up in went water but air already in system so had to hose that out.

bob
May 2009