An article I read said that the average residential ductwork allows up to 30% of heated and cooled air to leak out.
The majority of ducts are improperly designed and installed, including lots of sharp bends that restrict airflow through the system.
They are not sealed tightly at the seams, creating gaps that sacrifice a great deal of conditioned air. Over time, small holes can develop that not only give up heated and cooled air but pull in air, fumes and other contaminants from unconditioned spaces. Spending extra to purchase a high-efficiency furnace, heat pump or air conditioner is rather pointless if the ductwork compromises performance. Until coming across that article, it had never occurred to me to have the air ducts professionally serviced. I am quite conscientious about replacing air filters every couple of months and scheduling maintenance in the spring and fall. I researched to find an HVAC contractor that offers duct testing, cleaning and sealing in my area. There was one that is certified to provide Aeroseal duct sealing, which is an innovative process that targets imperfections from inside the pipes. Because the ductwork is often hard-to-reach, it’s advantageous to utilize the Aeroseal process. The contractor first tested airflow through the duct system and verified that approximately 20% of conditioned air was escaping. He then blocked off all supply and return vents and pumped pressurized air into the pipes. The air contained sticky polymer particles. As the air leaked from various flaws these sticky particles adhered to the edges and gradually created a tight seal. I immediately noticed an improvement in the comfort, efficiency and air quality of the home.