Are all HVAC air filters the same? No, HVAC air filters vary by quality and size, and some have technology that others don't. In most cases we recommend purchasing the filter your HVAC manufacturer recommends pairing up with your installed system, but you might be tempted to try some other filter type for convenience or to remove extra contaminants from your residence. Filters have MERV ratings, which range from 1-20. MERV stands for "minimum efficiency reporting value". A higher MERV rating tells you that fewer pollutants pass through, and it catches finer particulates. This sounds like a good thing, and it can be, but a filter that eliminates finer dust and dirt will also build up faster, and pressure on your unit will rise. If your system has not been designed to work with this kind of filter, it can decrease your airflow throughout your residence, impacting your comfort and energy expenses. So what should you look for? Unless you're buying for a hospital, you probably don't need a MERV rating above 13. In fact, most residential systems are specifically designed to work with a filter with a MERV rating below 13, and usually you will learn that quality systems have been made to work with a MERV rating of 8 or 11. All filters with a MERV rating of at least five should catch most of the common nuisances people care about such as pollen, pet dander, and dust. While some filters claim to be able to snag mold spores, we recommend hiring a pro to clean out any mold from your home you find, instead of trying to delay the issue with a finer filter. Often the packaging shows how often your filter should be replaced. There are one-month filters and there are 3-month filters. There are also filters that are made flat like screen windows, and you have some that are pleated with supporting wire. In our experience, the accordian style filters fare better, and are worth a little extra. You could also consider washable filters, also sometimes called reusable filters. Some homeowners like the environmentally friendly aspect of it, as they don't want to add to a landfill, and others believe it's more convenient to quickly yank out the filter and wash it off rather than making a run to the local hardware store for a filter of the right size. These filters are often made to endure several years and will save you cash over time, though they are pricier initially. However, washable filters do need to be dried out all the way before returning it back to prevent mold growth in your ductwork. In addition, most washable filters typically have a MERV rating between 1 and 4, and they lose their efficiency over the years. Some washable filters have been built with updated 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 we see most often, and are the disposable type. Polyester and pleated filters normally catch more debris, but also lessen the airflow in your house. And there are high efficiency particulate arrestance filters, which you may know as HEPA. While you may be tempted to put in a HEPA filter, just understand that's like putting a MERV 16 filter in your HVAC system and it's not unlikely that your unit was built to handle that kind of resistance.