Testing and Sealing Ductwork
Leaky ducts waste energy and contribute to a host of building problems.
Synopsis: Although most people don’t worry much about leaky ducts, they can cause a host of building problems, ranging from cold rooms to a life-threatening buildup of carbon monoxide. At a minimum, leaky ducts mean the air in the HVAC system isn’t going where it’s supposed to, making it more expensive to operate the system and more difficult to keep the home comfortable. A. Tamasin Sterner and Larry Armanda, both presidents of energy-related consulting businesses, explain how to use a pressure-pan test to identify duct leaks, and a duct-blower test to quantify leaks. They then share three strategies for making ductwork airtight: (1) using zip ties with flex ducts, (2) keeping ductwork in conditioned spaces, and (3) sealing subassemblies before installation. They recommend sealing small leaks with mastic, and larger leaks with fiberglass tape under a coat of mastic.
Unlike pipes, ducts don’t hold water, sewage, or flammable gases, so…