air in pipes?

ED_45

Has anyone come across this. Discovered a split in my htx60 expansion tank which I believe allowed air into my hot water heating system. I have 2 zones. 1 is a baseboard loop, the other is a column radiator system , with original piping and headers. I am getting pipe banging in the Cast Iron section of the heating system. But it happens mostly when the zone calling for the radiators, Taco 110 pump, is idle and the baseboard loop is calling. but there is no evidence of air in the baseboard loop. This ststem has operated flawlessly for 17 years but has been driving me crazy the last month.

Big Ed

Forget Air

Could be pipe expantion in the copper loop or your breaking steam some where in the iron pipe system. A drop in pressure caused by the bb loop circulator or thermal stacking in the large radiator system.What is the system reading as far as temperature......... step one