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What is a Furnace Fan?

A furnace fan, integral to your heating system, circulates warm air throughout your home, ensuring consistent comfort during cold months. It's the unsung hero of your HVAC, quietly working to maintain your ideal temperature. But how does it really impact your energy efficiency and indoor air quality? Discover the unseen benefits of your furnace fan and how it affects your living space.
Ken Black
Ken Black

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.

Furnaces employ fans to force hot air throughout a house.
Furnaces employ fans to force hot air throughout a house.

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.

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Discussion Comments


We used to keep our furnace fan running most of the time to keep the air circulating better in the house. I know they say this isn't supposed to shorten the life of the motor, but when we started doing this, we had to have our furnace fan repaired more often than we had before.

Now we only run our furnace fan when we have the heat turned on, and ever since we started doing this, we haven't had to call the furnace repair man.


We bought a couple of booster fans to work with our electric furnace fan. The bedrooms at the back of the house were so cold in the winter, and that is where the kids slept.

This was much cheaper than installing a new furnace system. I don't like sleeping in a room that is too warm, but you also don't want one that feels like it doesn't have any heat at all.


We had to have a furnace fan replacement and ever since they put in this new part, the fan seems to be louder than ever.

Our furnace happens to be right next to our bedroom, and the fan is so loud it keeps me up at night. I am thankful it works, and I have heat, but I get frustrated when the fan is so loud and it wakes me up at night.


Every fall I have someone come and check my furnace before winter. I want to make sure it is working properly before it gets cold outside.

One year I waited for as long as possible before turning it on, and it didn't work. I had to wait even longer than I wanted to before my furnace was working again.

The furnace fan motor needed to be replaced and it has worked fine since then. I am just glad this happened at the beginning of the season instead in the middle of winter.

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    • Furnaces employ fans to force hot air throughout a house.
      By: scaliger
      Furnaces employ fans to force hot air throughout a house.