Do you know where your Ducts are?

Air ducts form the backbone of your HVAC system. They are essential equipment doing their job quietly either below your feet, inside the walls or above your head. The only visible parts are the air supply registers which you see in the form of grills or louvers. In simple parlance, ductwork is basically a network of hidden tubes connecting your heating, ventilation and air conditioning.

Ducts were originally made of tin, but these were expensive. Galvanized steel solved that problem and became the material of choice as they were rust resistant and could also be bent into the desired shape easily. Ideally, sheet metal ducts are wrapped in fiberglass to make them thermally efficient. Other materials used for ducts are aluminum-coated polyurethane boards and fiberglass boards, which are also soundproof, flex or flexible plastic tubing that is extremely convenient to install but has higher pressure loss, which makes it unattractive, and fabric ducts, which are also known as airsocks or textile ducts. The airsocks, made of a special polyester material, are permeable and are generally used in cases where even air distribution is desired.

The key to good ductwork is balancing air flow. The real test lies in transporting the right amount of hot or cold air into different rooms simultaneously. The ducts which run around the house mimic the arteries in our body and the main duct branches off into various secondary pipes that should get smaller as they reach their exit points. A faulty design with respect to this will mean a sharp drop in air pressure; this would ultimately result in uneven climate control, hot and cold spots and wasted energy. Another idea to minimize energy loss is to place your heating and air-conditioning systems in the center of the home so that no room is at an extremity. Simple physics will tell you that the further you have to transport air, the higher will be the pressure loss. A well balanced system will also consist of dampers that can be manually controlled to shut off air supply to areas not being used, thus increasing the flow of air to other rooms. Last, but not least, exhaust outlets should be installed because the underlying principle of ductwork is circulating air in an efficient manner.

With regard to energy conservation, a well insulated and sealed duct will minimize the load on the HVAC system. A properly sealed duct can save upto 20 % of your energy bills. In addition, a professionally installed duct of the correct variety and size, with accurate air balancing, will also help cut costs. Some studies also point out that cleaning your ducting system may improve efficiency. The U.S Environmental Protection Agency on the other hand categorically states that cleaning ducts does not really improve efficiency or the quality of air in the home. Ducts need to be cleaned only if they are infested with vermin or mould.

Ducts not only circulate air-conditioned and heated air but also allow outside air into the house, and this brings dirt and other contaminants in. A good way to maintain indoor air quality is to install filters and in-duct humidification systems. As long as filters are changed regularly the ductwork will function like clockwork.