The Ultimate Guide to HVAC Air Filters

Filters come in a variety of types, sizes, and qualities, making choosing the right one somewhat of a hassle. And if any member of your family suffers from allergies, choosing the right filter is of the utmost importance. In this guide, you will learn how to navigate the filter section of your local home improvement store with ease, knowledge, and confidence. Armed with the information you need to determine the size, filter type, and necessary features to accommodate your needs, you will have no trouble finding the perfect filter. Our Arlington HVAC company explains everything!


Every home is different, but air contaminants in the average home include dust, pollen, dust mites, pet dander, bacteria, and sometimes mold. The problem with these common contaminants is that they slip through many standard HVAC filters and air ducts, which are only designed to filter superficial contaminants like dust and lint. Microscopic allergens and virus carriers can also pass through cheap filters.

House dust mite - Dermatophagoides pteronyssinus
Photo by Gilles Martin

Filter Performance Rating

To remove the contaminants mentioned above, you must pay careful attention to each filter's performance rating. HVAC filters are rated using a unit of measurement called the Minimum Efficiency Reporting Value (MERV). Although this term sounds complicated, it's actually quite simple to understand. The MERV scale runs from one to 16, with filters on the lower end removing fewer contaminants, and filters on the higher end removing most or all contaminants. The most common filters fall between one and four on the MERV scale, and they do very little to reduce air contaminants.

Photo by Beth Jusino

Stepping up to a filter rated between five and eight provides a notable improvement, but some allergens and contaminants, such as the ones that trigger asthma attacks, can still pass through. Filters rated between nine and 12 on the MERV scale are considered by informed consumers and professionals to be the best compromise between value and quality. When changed every three months, as any type of filter should be, these filters will remove a very high percentage of air contaminants.

The group of filters that span the ratings of 13 through 16 are the absolute most effective available, and they are known as high-efficiency particulate absorption filters (HEPA). However, the exorbitant cost and difficulty of installation associated with these filters make them a less convenient choice for the average homeowner.

Sizing, Disposability, and Sturdiness

Take care to correctly size your replacement filters. Sizes can vary as little as an inch, and choosing a filter that is too small will allow unfiltered air to pass into your system, lowering air quality and risking mechanical malfunctions. Depending on their materials and manufacturing process, some filters may be able to be cleaned and reused. After determining the level of filtration efficiency you desire, investigate to see if any reusable filters fit your needs.

Lastly, pay close attention to the sturdiness of the construction of the filter you choose. Flimsy construction may lead to bends and deterioration, which will lower the filter’s effectiveness.

Striving to elevate the quality of your home's air will benefit every member of your family, while also improving the comfort of your living space. The next time your filter is due for a replacement, reference these tips to make the best choice for your home.

Contact Tom's Mechanical to scheudle a service!