Anything that runs 24/7 will deteriorate faster than something that has rest periods. Even the ongoing stops and starts when you set the fan to auto are less damaging than what happens with months or years of constant use.
A constantly running HVAC fan can combat the number of bacteria and viruses within your home. According to the American Lung Association, the more your air circulates, the less chance the viruses have to spread. With air always on the move, bacteria and viruses can be pushed outside your home along with dirty air.
The average unit has a 500 watt fan, which uses almost as much energy over the course of the year as a refrigerator, resulting in a $50/month bill. During the summer months, the ducts in your attic and close to your walls can fill with warm air, resulting in the fan blowing hot air into your house.
Noise: A continuously running fan can create unwanted noise, which might be disruptive, especially at night. System Efficiency: Most HVAC systems are designed to operate with the fan cycling on and off with the compressor. Running the fan continuously can disrupt this cycle and reduce overall system efficiency.
Since the AUTO setting means the fan is only engaged when the system is on, rather than constantly blowing, AUTO is the most energy-efficient option between the two settings.
Compared to the ON setting, the AUTO setting gives you benefits such as: Lower energy consumption. In AUTO mode, the blower fan only runs when necessary, which cuts down your AC system's energy usage. Reduced wear and tear on AC components.
The fan will constantly blow air into your room if you have the thermostat turned “ON.” If it is on “AUTO,” it will only turn the fan on when heated air needs distribution. So yes, running HVAC continuously throughout the day and night is perfectly safe!
Therefore, the fan uses about 360 kWh per month in the ON mode. The average kWh in the US costs about $0.12 so it costs about $43 per month, or about $520 per year, to run a fan continuously.
If a standard air conditioner is in good order, it can run continuously without a problem. Wall or window AC units should only run eight to 12 hours before you turn them off. Running your AC nonstop will lead to higher electric bills and more repairs.
A ceiling fan is made up of different parts and pieces, and they will wear out over time. Sure, your ceiling fan can run throughout the day and night without issue, but running it for several days or months on end may not be the smartest choice and will reduce the overall lifetime of your fan.
Sometimes these two terms are even used interchangeably, but while both an air conditioner and air handler work together, they have very different functions. The main difference is that an air conditioner cools your air by extracting heat, while an air handler transfers this cool air throughout your house.
Lower Heating and Cooling Costs – It may sound counterintuitive that running a fan all day would lower your electricity bill, but it can often be the case—provided that you have a newer furnace installed.
Your typical central air conditioning connected to an air handler and using ductwork can last as long as 30 years with good luck and maintenance but will generally need to be replaced somewhere between 10 and 20 years.
This isn't necessarily bad for your fan, but it is usually a sign of a bigger problem. Common causes for fans not turning off when they should include faulty thermostats, bad wiring, and stuck relays. These problems are not easy DIY repairs and should be left to an HVAC professional.
Pros of Keeping Your Fan On
Hot spots occur when an area doesn't receive the same temperature-controlled air as other rooms. You'll also enjoy improved air quality in your home. Since the air constantly circulates through the air filter, it filters out more dust, allergens, and microbes.
An air conditioner running constantly can substantially increase your energy bills and stress the system's mechanical components. However, with careful management, you can keep your home just as comfortable while saving money on energy and repairs.
Some homeowners naturally worry about the risks of a breakdown if they run the fan all the time, but this will not be a concern for you if your HVAC system was properly installed and maintained.
Here's the thing: It's normal for your AC to run continuously during hot summer months. You see, on extremely hot days—we're talkin' high 90s to 100s—your system needs to keep up with the incoming heat. To do that, it will run longer in order to maintain a constant, desired temperature in your home.
The compressor should generally never run constantly, even if you always have your AC turned on. Typically, the compressor will run for a total of anywhere from 8 to 20 hours a day, depending on how hot the weather is.
While the answer is that there are pros and cons to both, I personally recommend using the “auto” function over the “on” function for your furnace fan. The amount of money you save and the boost in energy efficiency is the reason why. I also suggest having a smart thermostat installed in your home.
A constantly running fan will increase your utility bills and produce more humidity in your home because it will just blow warm air around without the AC absorbing moisture and heat.
"Most electrical fans are designed to be able to run continuously for several hours at a time, for example overnight or during the day, but you'll also need to keep in mind doing that continuously for long periods can cause wear and tear on the motor and other components, shortening its lifespan," continues David.
Leaving your air conditioning unit running all day won't typically cause damage to the unit itself, but it can strain the system and result in costly energy bills. Running your air conditioner non-stop for extended periods without regular maintenance leads to wear and tear on the unit.
If your fan limit switch is set to AUTO but the fan continues to run without ever stopping, you'll need to call a professional. Two problems that could cause your fan to run without stopping include: A bad fan limit switch that needs to be replaced. Bad thermostat wiring.
For example, a standard central air conditioner, like the one you probably have in your house, consumes between 3,000 and 3,500 watts of electricity per hour. That same AC when only the fan is running consumes 500 watts of electricity per hour. That's an enormous difference!