Dirty air ducts can create hazards in your home but they're often forgotten about when it comes to cleaning. Here's how often ...

Clues that it's time to clean your air ducts include: After a period of long inactivity, the system may initially blow out dust. But generally, the grilles and supply registers in room ceilings ...

Manual D, from the Air Conditioning Contractors of America (ACCA ... A single set of ANSI-recognized duct sizing principles and calculations that apply to all duct materials System operating point ...