Are all HVAC air filters the same? No, HVAC air filters vary due to quality and size, and some have technology that others don't. Usually we recommend using the filter your HVAC manufacturer recommends pairing up with your installed unit, though you could be tempted to try some other filter type for convenience or to remove extra pollutants from your home. All filters have MERV ratings, which range from 1-20. MERV means "minimum efficiency reporting value". A higher MERV rating tells you that fewer contaiminants pass through, and it captures finer particulates. This seems obviously good, and it can be, but a filter that stops finer dust and dirt will also clog up faster, and pressure on your system will rise. If your system has not been crafted to function with this kind of filter, it can actually reduce your airflow throughout your residence, impacting your comfort and energy costs. So what should you do? Unless you're buying for a hospital, you simply don't need a MERV rating above 13. Fun fact, most residential systems are specifically designed to work with a filter with a MERV rating below 13, and most often you will learn that more expensive systems have been made to function with a MERV rating of 8 or 11. All filters with a MERV rating of at least five should eliminate most of the common nuisances everyone cares about such as pollen, pet dander, and dirt. While some filters claim to be able to catch mold spores, we recommend removing any mold from your residence you find, instead of trying to delay the issue with a finer filter. Frequently the packaging tells how often your filter is recommended to be replaced. There are one-month filters and there are 3-month filters. There are also filters that are one flat piece, and you have some that are pleated with supporting wire. In our experience, the accordian style filters hold up better, and are worth a little extra. You may also consider washable filters, also known as reusable filters. Some homeowners like the environmentally friendly aspect of it, because they don't pile onto a wasteyard, and others think it more convenient to quickly yank out the filter and hose it off rather than making a special run to the local hardware store for a filter of the proper size. These filters are often created to endure several years and will save you cash over the long run, though they cost more initially. However, washable filters have to be dried out all the way before returning it back to stop mold growth in your vents. In addition, most washable filters reportedly have a MERV rating between 1 and 4, and they lose their efficiency over the years. Some washable filters have been built with new technology, such as electrostatic air filters, that are meant to effectively improve the MERV rating. Finally, filters are made of different materials. Fiberglass filters are what is commonly used, and are the disposable type. Polyester and pleated filters normally catch more debris, but also reduce the airflow in your home. And there are high efficiency particulate arrestance filters, or you might recognize the acronym HEPA. While you may be tempted to buy a HEPA filter, just consider that's like putting a MERV 16 filter in your HVAC system and it's not unlikely that your system was built to handle that kind of resistance.