When it comes to air filters, size matters. If you're looking to improve the air quality in your home, you need to make sure you're using the right size filter for your HVAC system. While a 1-inch filter may be the most common size, it's not always the best option. In some cases, a 2-inch or 4-inch filter may be more suitable.
But how do you know which one is right for your system?The size of the filter you should use is mainly determined by the size of your system. If your system only fits a 1- or 2-inch filter, then a high MERV rating could be detrimental. On the other hand, if you have a system that can accommodate a 4-inch filter, then this is usually the best option. Thicker filters, known as multimedia filters, are usually 4 to 5 inches thick compared to the ubiquitous 1-inch filters that can be purchased even at grocery stores. As an expert in air filtration systems, I can tell you that a filter with greater depth won't need to be changed as often as a thinner one.
So if you have pets or other allergens in your home, it's important to consider what type of filter will help keep the air clean and free of pollutants. If it's necessary to install thicker filters in a return grille, I recommend that you seal the return duct well and make sure it's airtight. Thicker filters produce more air flow (reduce pressure drop) and clog less easily. However, care must be taken with the MERV rating. If you want to improve air quality through better air filtration but don't want to incur the expense of modifying your equipment, then a 13-inch MERV filter is what you need.
Most furnaces and air treatment systems from major brands, including Trane, Lennox, Carrier, Rheem, Bryant, and Heil, come with 1-inch filter slots. If you're not prepared to change the filter every month (and if your system allows it), then a 4-inch filter is likely the best option. Placing a 4-inch filter in a location intended for a 1-inch filter can significantly affect air quality. Not only will the thickness of the air filter be important but also its MERV rating. Putting several 1-inch filters together is like trying to make a cup of coffee with 5 coffee filters - it just won't work. For comparison, a 4-inch-thick filter will have approximately twice the surface area of a 2-inch-thick filter.
That said, if you place a 4-inch filter on a 1-inch filter spot, this can affect your energy bills. In conclusion, when choosing an air filter, make sure to consider both its thickness and MERV rating. A thicker filter will provide better filtration and last longer than thinner ones. However, if your system only fits 1 or 2 inch filters then it's best to stick with those sizes. And if you're looking for improved air quality without modifying your equipment then opt for a 13-inch MERV filter.
