What Is a Cold-Air Return?
A cold-air return is a vent which sucks cold air into a furnace so that it can be heated and brought back to a room through a furnace register. Cold-air returns are seen in many types of furnace systems, although there are alternatives, such as drawing air from the outside, or drawing air from the area around the furnace. Depending on the design, each room in a house may have a cold-air return, or returns may be strategically located at various points around the house. A heating and cooling specialist can make recommendations about the number of returns and their optimal placement.
In addition to being used in heating systems, cold-air returns can also be used in cooling systems. In both cases, the benefit is that air drawn from a room is naturally closer to the desired temperature, which means that less energy is required to heat or cool it to the necessary level. Furnaces can also combine cold-air returns with a main return, a vent on the furnace which brings in air from the area immediately surrounding the furnace.
Typically, a cold-air return is located near the floor; because heat rises, the coldest air will be close to the floor. Locating a vent up high would leave pockets of cool air near the floor, which would be undesirable when the goal is to heat a room. Registers which emit hot air can be located at various heights, depending on the design of the system.
Often, the interface of a register and that of a cold-air return look identical. People can tell which is which by waiting for the furnace to turn on, and holding a piece of tissue in front of the vents. If the tissue is pushed out, the vent is a register, and if it is pulled towards the vents, it is a cold-air return. Both returns and registers typically have filters which prevent the passage of dust and dirt, and these filters need to the periodically changed to avoid clogging the vent.
People can control the amount of air moving through the furnace by opening or closing the vents on a cold-air return. With the installation of a new furnace system which takes advantage of existing ductwork, people may be told that they need additional returns or fewer returns, depending on how the system works, in which case unnecessary returns can be capped or simply closed, depending on personal taste.
Written by S.E. Smith
