Having proper air circulation has many health benefits and dramatically improves air quality helping you cool off on a hot day.
Atmospheric circulation continuously happens in the natural outdoor environment but mostly occurs indoors when the ceiling fan is turned on. In fact, with little room for ventilation in modern homes and buildings these days, fans are the only things encouraging air movement across the building—coupled with AC, moving a little air around can go a long way toward making the indoor environment comfortable.
Except when you are running your AC fan, and the system is not cooling. In this case, it will probably make you less comfortable than more.
If you are running your AC fan 24/7, you must stop now. You might think you feel cooler with the AC fan turned on between cooling cycles, but when the AC ends a cooling process, the unit’s fan is not just circulating the air, but raising the humidity levels inside your building.
Understand Your Thermostat Settings
To fully understand the issue regarding operating your AC fan 24/7, start by looking at your thermostat.
Whether you’re in cooling mode or heating mode, most thermostats will provide two different settings for AC, which are “Auto” or “On” for fan settings. When you’re using your AC unit, most people will advise you to put the fan in the ‘on’ position so the unit can better distribute the cold air around the house. But your HVAC has a feature that creates cold and heated air, and another that circulates that conditioned air. So, when you select the auto setting on your thermostat, the fan will only run when the AC activates its cooling/heating component. Setting the fan to the “on” position will mean the fan is always on.
The “on” setting on the thermostat should be avoided in the summer because it will cause you to use your air conditioner more than you want to, increasing your energy bills and humidity levels.
How AC Fans Increase Humidity
To understand how an AC Fan increases humidity, you need to consider what’s going on as air pulls through your air conditioning unit.
Air conditioners work by pulling the hot air from the room and into the indoor unit with the fan’s help. This air then passes over the evaporator coil, where it is cooled and dehumidified. The conditioned air is then radiated out through the condenser and circulated in the house by the same fan.
Now, when the fan is left on, even after the system finishes cooling, it will pull the air in and cause it to pass over the coil. But since the coil is no longer removing moisture from the air, it will pick up the residual humidity already on the coil from the previous cycle as it reenters the space.
Is Increased Humidity That Bad?
Air conditioners are good at removing moisture from the air. But the moisture condenses on the evaporator coil, and a lot of it is still there at the end of each cooling cycle. If the fan is left on between cycles, it will reintroduce the humidity into the house.
The increased humidity level in the building is counterproductive. It causes the air to become stickier, making you feel hotter and causing you to turn on your AC more often.
High moisture content will also contribute to feelings of low energy and lethargy. It might also cause hypothermia, causing your body to overheat due to the inability to effectively let out heat.
To avoid these problems, you can change your thermostat setting from “Fan” to “Auto.” Now the fan will only run while the AC is on.