The integrity of the duct system directly impacts the performance of the furnace and air conditioner. The branching network of ducts transports heated and cooled air to and from the rooms of the house. Even minor holes or flaws in the ducts allows conditioned air to escape. It makes it way more difficult for the furnace or air conditioner to achieve the temperature setting on the thermostat. Leaks in the ductwork forces the heating and cooling system to run for longer cycles and results in far greater wear and tear. More frequent malfunction, higher energy bills, and shortened service life are some of the consequences. These same holes in the duct system also allow outside, dirty, unconditioned air into the home. Dust, exhaust fumes, bugs, and all sorts of pollutants can be introduced into the indoor environment, creating a safety and health issue. It is a good idea to have the duct system inspected by a licensed HVAC contractor every couple of years. An HVAC technician has the tools to effectively test the duct system for flaws and handle the sealing process. While duct sealing is rather costly, it pays for itself through monthly energy savings. The technician will first seal off the supply and return vents, before injecting pressurized air into the duct system. The pressurized air contains adhesive particles which attempt to escape through the holes. As the air passes through, the particles build up and gradually seal the various leaks and flaws. The HVAC technician will repeat testing to ensure that the duct system is effectively sealed and provide a computer generated report of the findings.