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Duct Sealing

NADCA members in search of an add-on service to compliment an existing HVAC inspection, maintenance and restoration business sometimes consider duct diagnostics and sealing. The preparation work for sealing leaky ducts is very similar to many of the steps taken before cleaning an HVAC system.

Duct leakage is common because many connections are just not sealed during the construction process. Many times the air ducts are not installed with the proper support, and over time the joints pull apart. The areas to seal – in order of importance – are: disconnected and damaged components; air handling unit to plenum connections; and all joints and seams throughout the forced air system.

It seems as if there is no shortage of homes and buildings in need of duct sealing services, which is often caused during the construction or installation process of an HVAC system. On its Web site, the U.S. Department of Energy states: “If ducts are not sealed at the time of construction, moisture problems can develop in attics, crawlspaces, and other building cavities when warm humid air leaks into those cool spaces and condenses.”

The commercial realm is a good marketing target for duct sealing services, according to HVAC industry experts. The C.L.I. Group, a building and IAQ consultant in Cleveland, Ohio, states that: “While residential duct leakage is notorious, small commercial buildings actually suffer the worst duct leakage rates.” According to C.L.I., typical commercial buildings, on average, have HVAC systems that leak between 10-20 percent of the total air flow provided by the supply fan.