image courtesy of The Energy Conservatory
A duct blower performs a similar function on your HVAC ductwork that a blower door performs on your house. The duct blower fan is directly connected to the duct system, typically at a central return, or at the air handler cabinet.
image courtesy of The Energy Conservatory
With the remaining registers and grills temporarily taped off, duct airtightness is measured by either pressurizing or depressurizing the duct system and precisely measuring the fan flow and duct pressure.
image courtesy of The Energy Conservatory
• Leaks in supply ducts cause expensive conditioned air to be dumped into the attic, crawlspace or garage instead of the house.
• Return duct leaks pull outside air (hot in the summer, cold in the winter) into the duct system, forcing the cooling or
heating systems to run longer to keep the house comfortable.
• Return leaks can pull pollutants and irritants such as mold, insulation fibers, pollen and dust directly in the house.