HVAC fan settings . . .

Whenever your air conditioner is running, so is your HVAC fan. But it is up to you to set your HVAC fan settings. Whether you choose to run the fan after your home reaches its target temperature is the choice between cost and comfort.

Auto vs. On:

1. Most HVAC systems only have two fan settings: "auto" and "on". When your thermostat is set to "auto", the fan will only run simultaneously with the air conditioner to help distribute the cooled air. When it's set to "on", forced air will flow from your vents continuously until you change the setting.
2. The primary benefits to the "auto" setting are that it helps conserve energy and reduce wear and tear on HVAC parts, particularly the fan motor. It may also help you get a little more use out of each HVAC system filter, becuase air does not pass through it all the time. The downside is that your household air will gradually grow stagnant between cooling cycles. If you don't open the windows during the mild seasons, thing could get pretty stuffy before the air conditioner kicks on.
3. By using the "on" setting, you're dealing with the opposite situation. Air is being replaced continuously, so your indoor air will seem fresher and household odors will be less noticeable. Allergy sufferers may especially benefit from this endless circulation. On the other hand, the 24-hour cycle WILL show up on your energy bill, and your filters will need more frequenty replacement. You should also expect more frequenty maintenance, repairs and replacement of the fan motor.
4. Another potentional downside of using the "on" setting is that it can draw humid outdoor air into your home between the cooling cycles. Here in South Carolina, that humidity could cause problems. You could counteract with a whole-house dehumidification system if you need the continuous fan to improve your indoor air quality.

Need a compromise? If you find that you like the benefits of the "on" setting, but don't like the higher utility bills, a variable speed fan may be your answer. They offer greater customization of airflow during cooling cycles and in-between. You can program the units for high fan speeds while the air conditioner is on and slower speeds when the system is just circulating the air. This will give you more control of your fan settings! Call us at LHT Cooling, Heating and Refrigeration, Inc., for help with your HVAC fan settings!