When it comes to furnace filters, the general rule of thumb for many HVAC professionals is that the cheaper the better. That's why it's important to use only air filters with the MERV rating recommended by the HVAC system manufacturer. An ASHRAE study found that filters with a MERV rating of 4 or less met this standard, while a filter with a MERV rating of 8 doubled the pressure drop and a MERV rating of 11 tripled it. While a higher MERV rating may seem like a good idea at first, it's important to remember that it may not be the best for your specific furnace and air conditioning unit.
More expensive air filters, such as pleated residential filters, will filter out dust mites, pollen, pet dander, mold, and even bacteria, which can be worth the extra money, especially for people with severe allergies. We measure how well an air filter removes dust, pollen and smoke from the air, and we see how freely air flows through the filter at any fan speed. And the best filters trap indoor contaminants, such as dust, pet dander, and pollen, helping to clean the air in your home. Not only do filters remove dust allergens, mold spores, and other pollutants from the air your family breathes, but they also filter out fine dirt particles that can degrade the performance of the HVAC system itself.
The cheapest filters are made of spun fiberglass, which does very little to filter the air compared to materials such as paper, cotton or polyester. Dirty or clogged filters are never good for your system, and if you choose to use an expensive air filter instead of a cheaper one, it can be quite expensive. When comparing the cost of a pleated filter with a non-pleated filter, you have to triple the price per filter of the non-pleated filter to get an accurate comparison. Household HVAC air filters are rated based on their MERV rating, with most household filters between 1 and 13 (more than 13 are for HEPA filters).
They have little or no impact on fine particles such as pollen and smoke, so they won't do much to alleviate respiratory problems. But even with their limitations, these filters aren't useless. They extend the life of your equipment and help keep it running efficiently during heating and cooling seasons. You'll pay more for a washable air filter because it should last for years instead of months. No filter manufacturer can predict how long their filters will last because none of them know the dust conditions in your home, so you should check it often.
It's important to remember that while higher quality furnace filters may be worth it in some cases, they may not be necessary for everyone. It's best to consult with an HVAC professional before making any decisions about which type of furnace filter is best for your home.