No matter what type of HVAC system you have, it is important to use the right air filter for your system. Different HVAC systems require different air filters, and some have features that others don't. In most cases, we recommend using the filter that your HVAC manufacturer recommends matching with your system. For common brands of HVAC systems such as Goodman, Lennox, Trane, Rheem York, Coleman and Carrier, most standard air filter sizes will work.
Another rating method is the Clean Air Delivery Rate (CADR), a scale recognized by the Federal Trade Commission and Environmental Protection Agency that also measures the efficiency of air purifiers. Before making any changes to the air filter of an HVAC system, users should consult their HVAC manual or an HVAC professional. The higher the MPR, the better the filter's ability to capture particles from the air as it passes through the filter. To ensure that the next filter you purchase is the correct size for your system, you should measure the inside dimensions of the air cleaner inlet.
Air filters come in a variety of shapes and materials, each with different capacities and prices. In addition, an oft-cited comprehensive independent test of the effects of MERV filters 8 to 13 on HVAC airflow and energy consumption (an indicator of how hard the equipment is working) concluded that even “if no adjustments are made for the increased pressure drop of high MERV filters, the airflow and Energy penalties aren't likely to be severe at least, not until the filter is loaded with dirt. Some people need HVAC system filters that keep the air free of allergens and other contaminants, while others just need a basic filter to get the job done. Using a properly sized air filter for your HVAC unit is essential to keep your system running smoothly and reap all the benefits your air filter has to offer. Because pleated filters slightly improve the air quality in your home, they are a reasonably priced option for people who care about indoor air quality. If you live in an older home, with a non-standard size air return frame, you can use a foam weatherstrip tape to slightly increase the dimensions of your preferred filter or order a custom-sized air filter.
The right HVAC filters can make the difference between clogged air full of contaminants and clean air that is healthy and easy to breathe. We think manufacturers' concerns are a little cautious, partly because a recent innovation in air filters allows for high MERV ratings (11 to 1) with low pressure drop. In actual use, with the air in your home constantly recirculating through the ducts and passing through the filters each time, the cumulative effect of the filters increases.