Which furnace filter should you buy? That depends on how much dirt you want to catch in the filter and how often you want to maintain the filter.
Let’s talk about the 1-inch-wide filters most of us find in the return air ductwork on the side of the furnace. These inexpensive fiberglass filters remove some dirt. They will protect the furnace and provide maximum airflow.
If you step up to the inexpensive pleated paper filters, they will remove more dirt. They cost about $4 and need to be changed more often.
A good choice for most homeowners who are concerned with dirt and dust in the air is a higher efficiency pleated paper filter that costs about $10. They strike a good balance of cost and efficient dirt removal. Still, you should make a reminder note to check the filter routinely. You’ll see when it is dirty. When you replace it, check the direction of the air flow so you can install the new filter in the correct orientation.
A plugged filter will lower the efficiency of your heating and cooling system, and it can eventually cause the unit to shut down. When switching to a higher efficiency filter, it’s wise to ask your service technician to recommend the best filter for your home.