How Can HVAC Fan Settings Affect Your IAQ and Utility Bills

If you have been using your thermostat for a while, you probably know that it has two fan settings: “AUTO” and “ON.” But do you know the difference between the two, and how each can affect your HVAC performance, indoor air quality, and energy bills?

Let’s take a look.

What thermostat AUTO and ON settings mean

When your home HVAC system is heating or cooling air, its blower fan (a fan that helps to push conditioned air through your home’s ductwork) is on. But when your HVAC system is not heating or cooling air (once your home reaches its target temperature), you have a choice whether to keep that fan running:

• AUTO means the fan turns on ONLY when your system is heating or cooling air for distribution.
• ON means the fan is CONSTANTLY blowing, even when your system isn’t heating or cooling air.

Pros and Cons of AUTO and ON

The key benefits of the auto setting are that it reduces energy use (and your bills as a result) and reduces wear and tear on HVAC parts – especially the blower fan motor.

Choosing Auto may also help you squeeze a little more life from your HVAC filter, since less air and fewer particles are passing through it. Of course that also means that your filter will trap fewer pollutants.

Switch your thermostat to “on” and you’ll have the opposite costs and benefits: since air is constantly moving, your indoor air will seem fresher – good news for allergy sufferers.

On the other hand, your monthly energy bill could rise as much as $40-50 a month, and your air filters will need more frequent replacement. You will also more than likely need to service your HVAC equipment more often – and you run the risk of drawing in more humid (and dirty) Massachusetts air in from outside.

What HVAC setting is right for you?

As you can see, the HVAC setting you choose for your thermostat depends on your priorities – typically, it comes down to comfort/air quality vs. cost.

There is a third option, however: many newer thermostats will have a variable speed blower or “circulate” option, which allows you to set the fan on for a certain amount of time every hour. The blower will automatically run at different speeds, giving you the benefits of lower electrical bills and increased comfort.

Have any questions about thermostat and HVAC fan settings, or about the HVAC system in your Massachusetts home? Contact the pros at Pioneer Oil and Propane today.