In typical houses, about 20 percent oi the air that moves through the duct system is lost due to leaks, holes, and poorly connected ducts. The result is an inefficient HVAC system, high utility bills, and difficulty keeping the house comfortable, no matter how the thermostat is set.

  • Inspect the whole duct system, including the attic, basement, and crawlspace (if you have these).
  • Evaluate the system’s supply and return air balance. Many systems have air return ducts that are too small.
  • Seal gaps behind registers and grills where the duct meets the floor, wall, or ceiling.
  • Insulate ducts in unconditioned areas with insulation that carries an R-value of 6 or higher.
  • Repair or replace damaged, disconnected, or undersized ducts and straighten out flexible ducts that are tangled or crushed.
  • Seal leaks and connections with mastic, metal tape, or an aerosol-based sealant.
  • Include a new filter as part of any duct system improvement.
  • Use diagnostic tools to evaluate air flow after repairs are completed.
  • Ensure there is no back drafting of gas or oil-burning appliances, and conduct a combustion safety test after ducts are sealed.

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