One of the most common questions posed to HVAC companies is should I run my AC unit fan continuously? In fact, this is a hotly debated topic throughout the entire heating and cooling industry, and it would be hard to answer it definitively here. Although running the fan does consume energy, the pros may outweigh the cons for some people. In this article, we will take a closer look at the issue by presenting the advantages and disadvantages to help you make an informed choice.

3 Pros for Running the Fan Continuously

When you set the fan to the "On" position, it will run continuously until you decide to turn it off again. This means the fan is running 24/7 every day, no matter the current heating or cooling settings. This may seem like a strange thing to do, but there are three main pros to adopting this approach, they are:

  1. When you run the fan continuously, the heating and cooling distribution tend to be more even. If you tend to have hot or cold spots in your home, this may be helpful to make those areas more comfortable. This type of phenomenon is more noticeable in a bedroom that's located above a garage.
  2. Continuously running the fan can be helpful if you have an air purifier or ultraviolet purification system for your indoor air. The fan will pull fresh air into the home constantly. This can be very beneficial for people suffering from conditions such as asthma, allergic reactions, and pre-existing breathing conditions.
  3. When the fan isn't starting and stopping, the stress of the startup is minimized. This could extend the useful lifespan of the component and reduce the frequency of repairs.

As you can see, aside from the obvious consumption of energy, there are a few advantages to running an HVAC system fan continuously.

3 Cons for Running the Fan Continuously

If you're thinking of running your fan continuously from now on, take a quick look at our list of three cons to see if this is still a good fit for your home.

  1. The most obvious drawback is the extra energy that you will expend when you run the HVAC system fan 24/7 for 365 days of the year. This may seem like a trivial expense, but it could cost you hundreds of dollars per year to run your fan in this way. An average sized 500 watt fan consumes around as much energy as a standard refrigerator that can cost $50 per month to run!
  2. When air is pushed through the system constantly, it will cause the furnace filter to clog faster than usual. For this reason, you will find that you need to change the filter more frequently to compensate. Running the fan constantly does not harm the furnace, but more material will accumulate on the surface of the filtration media.
  3. If you run the fan in this way during the colder winter months, you may experience cold air coming from your vents. The air temperature is relevant to the space temperature, but it will feel colder because it's circulating more often. Essentially your home will feel colder even though it really isn't.
  4. Running the fan over the hotter summer months will cause the ducts, and those located near walls will be filled with warmer air. This will be distributed throughout the home, and this will heat up every room. In order to compensate, the air conditioner will need to work harder to get rid of the extra heat. This can cause the equipment to overwork leading to a repair bill or an earlier than anticipated replacement. Another consideration is that the warmer air will be dirtier and more humid, which will affect the indoor comfort levels.

Are There Any Alternatives to Consider?

Reading the pros and cons above would seem to indicate that running the fan continuously is a mixed bag. But, there is an alternative that you may want to consider, and that's setting your HVAC fan to the "Auto" position. The "Auto" setting means that your HVAC fan will only run when it is instructed to by the unit. This may seem like the perfect solution, but there are also pros and cons to this approach that we will detail next.

3 Pros for Running the Fan on "Auto" Mode

There are some solid advantages to running your HVAC system fan using the "Auto" setting; they are:

  1. This is a cost effective way to run your fan because you will use less energy overall. The "Auto" setting will work with your heating and cooling system, and it will only run for the time it's required at the slower speeds.
  2. Because the air is pushed through the furnace filter less often, you will notice that this component can be replaced less often.
  3. Running the HVAC system fan on "Auto" will provide better humidification for your home. The gathered moisture will have time to drip off the colder cooling coils and enter the drain outside. If the fan runs all the time, the moisture cannot drip away efficiently, and it can blow back into your home. This makes the indoor air feel wetter, and the air conditioner has to work harder to remove it again.

2 Cons for Running the Fan on "Auto" Mode

There are two main disadvantages to consider if you want to run your HVAC system fan using the "Auto" mode, they are:

  1. The frequent stopping and starting of the fan can cause that component to wear out faster, leading to a repair or replacement.
  2. The distribution of treated air in the home can be less even because once the thermostat temperature is reached, the fan will stop again.

Which is the Best Setting?

As you can see, there are good reasons why HVAC industry experts tend to argue about this subject. There is no easy answer because people tend to use their HVAC systems in different ways to achieve their ideal indoor comfort levels. If you have people living in your home with allergies keeping the fan on all the time makes good sense. But, if the home is empty when you're at work and you want to save money, it makes better sense to choose the "Auto" setting. A good alternative is a variable speed blower system that can turn the fan on for a set time each hour at different speeds. This is a compromise between the two approaches, the energy bills are increased a little, but the comfort levels are higher.

If you want to install a variable speed blower, contact your local certified HVAC specialist today.