When it comes to improving air quality, a 4-inch thick air filter has a clear advantage over a 1-inch filter. With a 4-inch filter, you can get a higher MERV rating, up to 16, which can control supermicrocontaminants such as bacteria, viruses, and dust particles. In comparison, 1-inch filters only cover a range of MERV ratings up to 4 and are not as effective in trapping particles. Additionally, 4-inch filters can last up to 3 to 6 months, while 1-inch filters need to be changed every 30 days.
When shopping for an air filter, you'll find that most home improvement stores sell HVAC filters ranging from MERV 1 to MERV 13. However, some filters with mid-range and higher MERV ratings can cause problems in residential HVAC systems. This is because they are more restrictive than MERV 1-4 filters and can trap mold spores and pet dander along with dust and pollen. If you want the best air quality, you should buy a filter in the MERV 13-16 category. However, it's important to note that these filters can cause problems in residential HVAC systems if they are not installed correctly.
Poorly installed one-inch filters can cause air to circulate around the frame, even causing the frame to bend and deform. To ensure that your filter is installed correctly and is working optimally, it's best to use a 4-inch filter. This is because they have much stiffer cardboard frames and some even have plastic “rails” on the top and bottom so you can slide them inside the oven with a very tight seal. Additionally, 4-inch filters have four times more filter media than 1-inch filters, which means they can capture more waste.
If you need a high humidity filter for air purity due to respiratory problems, it's best to buy an external air purifier. This will help control the extent to which each filter restricts air flow and will ensure that your heating and cooling system is not overworked.