Leaks in forced air duct systems are now recognized as a major source of energy waste in both new and existing houses.  Cracks and holes cause a typical system to lose 15% to 40% of its heating and cooling capacity.  Air conditioning systems are normally sized to remove an estimated amount of heat gain into that specific building.  If more heat gain is experienced or less cooling occurs, the HVAC system usually can't keep up.  In addition, on hot days the actual capacity of the HVAC system may be further reduced.  Buildings with leaky return ducts in attics or chaseways will pull 120 degree air into the system, making the air flow warmer as it goes to the cooling coil.  Most coils can only drop the incoming air temperature by 20 degrees, so the outgoing air that arrives to your rooms is warmer than it should be, making it harder to cool the rooms.

Supply duct leaks affect the run time of the A/C unit in a different way.  As heat is removed from the air stream at the coil, the cold air is forced by the fan down the duct, into your room. That cold air is under pressure and is looking for an easy way out. Cracks at duct joints, connections, elbows, fittings and register boots will leak some of this air to the outside before it gets to your rooms, making it harder to satisfy the thermostat.  Supply duct leaks also create a negative pressure in the building, which pulls in warm outside air.  Worse yet, duct leaks can create air quality problems by pulling pollutants and irritants from attics or crawl spaces directly into the house.  Every year, Americans spend millions of dollars replacing what they believe to be inadequate heating and cooling systems, when the real problem may be leaking ducts.  A quick, low cost inspection by a BTAC technician can pinpoint problems in your duct system and make your energy bills, your air quality, and the lifespan of your HVAC equipment much easier to live with.