I have an American Standard 2 zone HVAC system. For the last 2 days there has been a banging noise when the heat is on. It is coming from the Honeywell zone valve box for Zone 1 which is visibly moving with the banging. The noise then echoes througout the system and is driving me batty. The system is only 3 years old. I did have a major water leak from the unit in the summer when the AC was on, which was from a clogged pipe and was fixed by the installer--so maybe that caused damage.
Does anyone know what this means, how bad it is, and if I have to call a heating service person to fix it?