How HVAC Fan Settings Affect Your Air Quality and Utility Bills

Posted: June 24, 2019

HVAC fan settings

Most people have been told to keep their home thermostat set to “AUTO” instead of “ON” for both heating and cooling their Maine home. But what is the difference between these two settings?

Let’s take a look.

What AUTO and ON mean

When your home HVAC system is running, so is its blower fan (a fan that helps to push cool air through your home’s ductwork). But it’s up to you whether the fan should continue to run after your home reaches its target temperature — and the choice generally comes down to cost vs. comfort.

You control the HVAC system’s blower fan via your thermostat, using the “auto” and “on” settings:

Auto vs. On: Pros and Cons

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 fan motor.

Choosing Auto may also help you squeeze a little more life from your HVAC filter, since it reduces the amount of time that air will pass through it. Of course that also means that your filter will trap fewer pollutants, since it won’t be running as often.

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 – a boon 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) Maine air in from outside.

What HVAC setting 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 Central Maine home? Contact the pros at Murray-Heutz Oil and Propane today.