By simply sealing your ventilation system (ductwork) you can save up to thirty percent on your energy bills. Air is forced through the ducts at high velocities. Any holes or leakage can cause air that is supposed to be going to conditioned areas to be lost to non-conditioned areas (supply leaks). Also, air from non-conditioned areas can enter the conditioned living area (return leaks)(see health and safety). The supply ducts are the ducts that usually come off the top of the furnace. They are the ones that blow the air into the house. The return ducts are the ducts that usually go into the bottom of the furnace and have a filter in the line. They are the ones that draw or suck air from the living area's air.
If you picture your home like a balloon, you can get a picture of how the air distribution system should be a closed loop. Your ducts are intended to force air ONLY into the conditioned living space. If you have more air going into the living area then leaving, you will blow up the balloon or "pressurize" the conditioned area. Energy will be pushed out of all air opening in the home, wasting energy. In reverse, if you have more forced air going to the non-conditioned areas, then entering the home, you will have "depressurization", again wasting energy. Our instructions in the booklet will help you find both types of leaks and neutralize your house pressure. This inexpensive fix can save you hundreds of dollars a year.
Health and safety is a critical issue when looking at the air distribution system. After any duct sealing, simple tests should be done to assure that no dangerous combustion byproducts or pollutants can enter your home.
If you were to seal the supply ducts and not the returns, then gases and pollutants from the basement could be "sucked" in the duct work and then into the living area. Also, if the air that was being forced into the basement through supply leaks is sealed, gases that were once pushed up or drafted out the chimney could easily "backdraft" into the house. Carbon Monoxide is one of these gases. Carbon Monoxide is the number one cause of poisoning deaths in the United States. We recommend Carbon Monoxide detectors for all homes. Sealing duct systems is an excellent way to save money, and stop byproducts, pollutants, and moisture from entering the air you breath.
The amount of air that moves through your distribution system is really a science best left to the expert, but the laymen can make a visual determination of the correct air flow. Furnaces that heat and cool normally have a dual speed fan. It takes a higher fan speed to push cooled air. Also larger volume ducts are needed to handle air conditioning. We find many homes that have had air conditioning added and the duct size was not increased. For every "ton" (many units are 2-3 tons) of air conditioning, you need 400 CFM of air flow. If air flow is inadequate, the cool air will not be moved across the coils and the unit could freeze up or not produce proper cooling. Our booklet has a quick formula to determine this.
One of the fastest way to save hundreds of dollars a year is to "change the air filter regularly". Regularly means every three months that it is used. A dirty filter is like a piece of cardboard, restricting air flow. Furnace fans regularly burn up because of this. If air cannot get into the furnace, it will not come out!