How Do Furnace Filters Work?

furnace filter

As a homeowner, your furnace probably doesn’t cross your mind much – that is, unless it’s not working or causing an inflation in your energy bill. However, buying and changing your furnace filter is a task that should be on your to-do list to avoid problems with your furnace down the road. But do you know the different types of filters or how furnace filters work?

Furnace filters have an important job. They’re designed to protect your furnace’s blower fan from the dirt that it pulls into your furnace. That dirt includes the dust, hair, pet dander and other air-borne allergens in your home.

Many homeowners think that a furnace filter is meant to clean the air in a home, and while it does help with your home’s air quality, cleaning your home’s air is not actually the main purpose of a furnace filter. Instead, it’s designed to protect your furnace parts, keeping them as clean as possible so that they last longer and your furnace functions properly.

To do this, the furnace filter traps unwanted dirt particles which prevents the particles from recirculating throughout your home. To ensure your furnace filter is working optimally, you need to ensure you have the right sized filter for your furnace, as well as a filter that’s highly rated.

About Furnace Filter Ratings

Furnace filters for your home will come in different fabric densities. The furnace filter ratings, called MERV (which stands for Minimum Efficiency Rating Value) indicate how dense the filter’s fabric is. The MERV ratings run on a scale from 1 – 16 (1 is the least dense and 16 is the densest). The higher the MERV rating, the smaller the particle size that it can collect. In other words, the denser the filter fabric, the more dirt and air borne pollutants that are trapped in the filter’s fabric.

No matter the MERV rating of your filter, you’ll still need to change it regularly to ensure the filter stays clean. A dirty filter can cause a lot of problems for your furnace as well as your home, including increased energy consumption, inadequate and uneven heating, mechanical malfunctions with the furnace itself, as well as poor air quality (which can ultimately cause health concerns for your family).

furnace filter

Types of Furnace Filters

When it comes to furnace filters, there are different types:

  • Disposable filters like fibre-glass or pleated throw-away filters often have a low MERV rating of 1 – 4 depending on the brand and type. These filters need to be maintained or replaced every three to four months.
  • Air screen filters tend to have a MERV rating of between 4 – 7 depending on the brand and type, and again, should be maintained or replaced every three to four months.
  • Media filters (known as cartridge style filters) have an average MERV rating between 8 – 16 and should be maintained or replaced every three to twelve months, depending on the brand and type.
  • Hybrid Air Cleaners, like the Aprilaire 5000, have a MERV rating of 15 or 16 depending on the brand and type. These typically need to be maintained every nine to twelve months.

Have questions about your filter furnace or looking for furnace maintenance? Give the team at Appleby Systems a call. We’re ready to help with all your furnace needs.