Everything You Need To Know About Furnace Air Filters

The air filter is one of the most overlooked yet critically important components of your furnace. Not only does a furnace air filter maintain the air quality in your home while your furnace is running, it also prevents dust and debris from collecting on the blower fan, which can cause the whole system to run less efficiently and potentially even break down.

While it’s usually best to leave furnace maintenance to a licensed HVAC professional, changing the air filter is something you can potentially do yourself, provided you’ve done your research.

Here are the answers to some of the most commonly asked questions about furnace air filters.

What Furnace Filter Should I Buy?

While furnace air filters are relatively simple devices, there are a number of different types, sizes, and ratings to choose from. The one you purchase should be based on the specifics of your HVAC system and on your own personal preferences, so the better question to ask yourself would probably be, “what furnace filter do I need?”


Fiberglass or Synthetic – The most affordable, but the least effective. Will not maintain the air quality in your home.

Polyester – Significantly more effective than fiberglass/synthetic filters, and significantly more expensive. It Will help to clean the air of pollutants.

Pleated – Highly efficient at cleaning pollutants from the air and allowing maximum airflow through your HVAC system. The most commonly used furnace air filter.

Electrostatic – Comes in a range of ratings, and can be both disposable or reusable.


Furnace air filters are measured in three dimensions: height, length, and depth. The best way to know what size filter your particular furnace uses is to take a look at your old one, or read your user manual.


The rating system used to gauge how effectively a furnace air filter removes pollutants from the air is known as MERV, or minimum efficiency reporting valve. MERV ratings run from 1 to 16, with the highest number being the most effective, and the most expensive. The rating you choose depends on how clean you want your air, and how much you’re willing to spend.

Can Furnace Filters Be Cleaned and Reused?

If you’re wondering, “can furnace filters be washed and used again?”, the answer is yes and no. Many furnace air filters need to be replaced every 60-90 days, and should not be washed and reused, but there are certain types of filters that are made to be reusable. Some electrostatic filters, for example, can be washed off with soap and water and reused for up to 5 years.

Note: always be sure to dry off your reusable filters before use to prevent issues with mold and mildew.

But if you’re an eco-conscious person with a disposable filter, you may be wondering, “can furnace filters be recycled?” Well, yes they can, but it requires a bit more effort than just tossing them into your recycling bin. You’re going to need to mail your disposable furnace filters to a recycling company. Contact one and they will send you the postage.

Will the Furnace Run Without a Filter?

In cases of emergency, a furnace can run without a filter, but it is not suggested for much more than one night. Any longer than that, and you’re likely to be calling in the HVAC specialists at Rowland Air to come to take a look at your system.

Rowland Air offers excellent routine maintenance services for your HVAC heating and air conditioning systems to keep it in top shape. We will also show you how to change your air filters so you can do that once a month to keep everything operating efficiently.