A furnace fan is the main component of a furnace system that forces air into an area of a home where heated air is needed. Most central heating systems in existence today are forced air systems and therefore require air to be moved in some way. A furnace fan, also known as a furnace blower, is one of the easiest ways to accomplish this.
In a heating system, after the air is heated, it must have a way of getting to other areas of a building. The heated air travels through the duct system to those other areas. However, without a catalyst, the air would lose much of its heat by the time it arrived at its intended destination. A furnace fan moves the air much more quickly than it would move on its own.
Most furnace fans come with a motor that is one horsepower or less. The size of the motor used may depend on the size of the furnace. It may also depend on the size of the area being heated, as well as how many opening or vents there are in the home. While most furnace fans are capable of speeds of 1,200 revolutions per minute (RPM), some spin at slower speeds. The maximum speed of most fans for residential furnaces is 1,500 RPMs.
Though many may be tempted to blame the furnace fan for rooms that tend to be drafty or colder than other rooms, the fan is usually not the culprit. Often, those rooms that are cooler than the others are at the end of the duct line. Most of the heated air has been distributed to other rooms, much like a hose full of holes will have less water pressure by the time it gets to the end. Solving this problem does not involve replacing the fan, but reducing the number of open vents.
If this is not possible, there are fans that can go on the outside of vents to help draw heated air through the system and into a particular room more effectively. This will not replace a furnace fan, but rather work in conjunction with it. These booster fans can often cost between $10 US Dollars (USD) and $100 USD.
Some may choose to keep a furnace fan running even if the furnace burner is not in operation. This is done to help circulate air through the home, which may help reduce stuffiness and add humidity to certain rooms. Running a furnace fan without the heat on does not substantially shorten its life, though all motors will eventually wear out.