Whenever I change my air filters in my furnace, I hear a boom noise. The last time I called DEER and they came out and fixed the problem (I can't remember what the part was called that was needed). It happened again, the booming sound, after I changed the filters. What could be causing this problem and how can I get it fixed and never have it happen again, even after changing the filters?
Assuming no sledgehammers were used, you could be hearing a sheet metal change shape, triggered by temperature. It will likely be a large flat area of metal somewhere...