I’ve a noisy HVAC system around my house. When my air converts on, it makes a loud banging sound in addition to when it cycles off. I guess I should get my HVAC provider to come out and review my metal vents and the ductwork as the sounds are more then likely associated with them. It is more of an rattling sound than anything else. I had my HVAC contractor come out to clean my air ducts earlier the year of 2010 and he didn’t say that he saw anything wrong. I am afraid there will be a leak in my ductwork somewhere and that’s associated with the noise. If I have a leak in the ducts, it could make my air run longer and that could not solely damage my HVAC system, but it could also cost me a small fortune on my utility bills. Actually, I know the last time I had my HVAC system replaced, my HVAC provider said that he found a leak in the ductwork. After he installed the popular centralized heating and air conditioning system, I noticed a major savings on my utility cost monthly. I am not sure if that was a result of the new HVAC unit, or since he found and patched the leak at my ductwork. I guess I need to have him come out again to inspect my HVAC system. Maybe it’s something simple like a loosened nut that holds an air vent down. Then again, it is also something mechanical in my environment handler. If it is something mechanical, then I guess it would be best to get it fixed before something breaks in my HVAC system.