HVAC Filters 101: All Your Questions Answered

If there’s one thing we get questions about all the time, it’s air filters for air conditioning systems. These questions typically include:

  • How often should I change my filter?
  • Where is my filter located?
  • Which type of filter should I buy?
  • Will an expensive filter improve my indoor air quality?

Our answers will save you time and money!

How Often Should I Change My HVAC Filter? 

We recommend you change your HVAC filter every 30-60 days for optimal performance. If you have a pet, especially one that sheds a lot, keep it closer to every 30 days especially during the heavy use months in summer and winter.

HVAC filter pets

A visual inspection of your filter after 30 days will help you determine if it’s time for a switch. A filter with thick, clogged dust and debris is a clear indicator that your A/C system needs a fresh replacement!

Where is My Filter Located?

Your A/C and furnace filters could be in a variety of places, including on walls, ceilings or floors of hallways or rooms, or even within the HVAC system itself.

clean air filter

Contact us and we can help determine all of your filter locations on a service visit to make sure you’re changing them in all the right places.

Which Filters Should I Purchase?

Air filters are actually meant to protect your system rather than improve indoor air quality. When you keep contaminants and debris out, your system will run better and longer with fewer repairs. In fact, the US Department of Energy estimates that HVAC systems with clean filters can be a full 5-10% more efficient and prevent early system failure.

clogged air filter

However, when you enter the filter aisle of a home improvement store you’re bombarded with many expensive options supposedly useful for air cleaning, allergen protection, etc.

We recommend (as do leading HVAC system manufacturers) that you purchase the absolute cheapest fiberglass air filter available to maximize air flow. Thicker filters or ones with high “MERV” ratings can actually slow down air flow which will not allow your system to run as effectively. (creating the same effect as having a dirty, clogged filter)
bobvila2Even Bob Vila agrees that thicker filters are not necessarily better, indicating that they can “create more resistance in airflow than a system is designed to manage, thus making it inefficient.”

If your house is like most homes in Gwinnett and the surrounding areas, you have significant duct leakage; an average of about 30% lost to unconditioned areas. If that’s true, then when your HVAC system kicks on, it’s creating a negative pressure inside your home and your system is working overtime to keep up. Stuffing a nice, plump, pleated filter in it is like stuffing a blanket over your mouth when you’re trying to run uphill. Make sense?

Will an Expensive Filter Improve My Indoor Air Quality?

If someone in your home has allergies or if a doctor has recommended home air filtration, you’ll be much better off with a product like the Aprilaire Air Purifier which is specifically designed for this purpose and captures 98% of dirt, allergens and particulates in your home’s air all before it reaches the system.


If you’d like to discuss your HVAC filters or if you have any other A/C related questions, feel free to give us a call at 770.271.7511. We’re always here to help!

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