I hope someone can answer this. I moved into my condo this spring, and this noise just started once the weather started getting cold and I presumed it was related to the heat. Not mine, but perhaps from the unit above me. It did not occur all summer or while using the AC. The noise sounds like a popping or banging in the ceiling and is fairly consistent during the night, which actually prevents sleeping. I have read some things, but not sure what it is or what I can do. Thanks