When my heating bill was a little higher every month, I knew there was a problem.
I am very conscientious about having the furnace professionally inspected, cleaned and tuned every fall. Because of this, I was suspicious that the ductwork was to blame for the rising heating costs. The furnace was definitely running longer and yet having a hard time meeting demands. Certain rooms in the house were consistently chilly. Since the duct system is concealed inside walls, ceilings and crawl spaces, I was unable to check it out. I hired a professional HVAC contractor to provide duct testing. He determined that approximately 30% of my heated air was escaping through leaks at the seams and small holes, and recommended duct sealing. At one time, the duct sealing process was very labor intensive. Technicians were required to manually locate and repair each flaw in the ducts. There is now a process that seals the ducts from the inside out. Aeroseal duct sealing works by sending pressurized air laced with adhesive polymer particles into the ducts. As this air escape through the various imperfections, the particles stick to the edges, build up and gradually seal the holes. The process takes a few hours to complete but causes no damage or disruption. There’s no unpleasant smell or mess left behind, and the service is warrantied to last for a minimum of five years. The HVAC technician then tests the duct system to ensure the results. I was amazed by the improvement in the cleanliness, smell and comfort of my home. I was extremely happy with the much lower utility bills.
Information here