The “auto” and “on” settings on an HVAC’s system blower may seem one and the same to many people, but they’re actually two different functions. In this blog, local central heat and air company M&M Heating & Air Conditioning Service Co. shares a look at these differences and the benefits of each.
On vs Auto
HVAC systems generate conditioned air by blowing air through coils that are heated or cooled. When you switch your blower to “on,” this means the fan will blow air continuously, even when the heating or cooling coils in your HVAC system aren’t activated. On the other hand, setting the fan to “auto” means it will turn on automatically when your HVAC system is blowing conditioned air. Once the room reaches the desired temperature, the fan will shut off until the next heating or cooling cycle.
Why Set Your Thermostat Fan to “On”?
Letting your thermostat fan run uninterrupted allows for continuous air circulation throughout the house, which helps ensure the even distribution of warm or cool air. It also helps prevent particulates from a fuel-burning furnace from recirculating, as the air will be filtered at the intake registers. Continuous operation also puts less stress on the thermostat fan (as opposed to stop-start operation), making it less likely to break down. Keep in mind that air filters usually get clogged faster when the thermostat fan is set to “on”.
What About Setting Your Thermostat Fan to “Auto”?
Setting your thermostat fan to “auto” consumes less energy, as the fan only runs when it needs to blow conditioned air into a room. This setting allows more efficient dehumidification, which helps get rid of excess indoor humidity during warm summer months. Breaks during its operation allow moisture from the cooling coils to drip and drain into the condensate pans. If you prefer to keep your thermostat fan to auto, you may need to have a separate dehumidifier in the room.