Air leakage from
ducts can drastically lower the efficiency of forced air systems. Proper
sealing and installation of ductwork is extremely important. Standard "duct
tape" is not an effective product to seal ductwork. Mastic sealers and foil
tape with a butyl rubber backing are superior products. An air leakage test is
recommended when sealing ductwork. Leaky areas can be identified and sealed
properly when using this device to measure results.
Duct insulation is also important. Metal ductwork should be
insulated with R-11 insulation and flex duct should have a minimum of R-8. Flex
duct should have gradual bends so air flow isn't restricted.
Connections between sheet metal and flex ducts should be
secured with metal or nylon clamps and sealed with mastic or foil tape
mentioned above. Flex ducts should be supported with at least one-inch wide
supports. Stretch the duct to its full length so air passages are as smooth as
possible.
Accurate ductwork sizing and balancing is critical for
proper air flow. Heat pump systems require greater air flow and larger duct
sizes than forced air systems. Select a contractor who can properly size and
install both your forced air system and ductwork.
