What is a furnace filter?


If you are like most homeowners in Central Ohio you’ve had to change your furnace filter at least once this year. Furnace filters are one of those things that everyone has but rarely talks about. Let’s change that.

Video Transcription

Let’s talk furnace filters. In this video we’ll go over what they are, what sets them apart and even how much they cost.

Hi, I’m Luke from Fire & Ice. Like most homeowners in Central Ohio, you’ve had to change your furnace filter at least once this year. Furnace filters are one of the things that everyone has but rarely talks about. Let’s change that. In this video we’re going to break down filters and discuss:

  • What is a furnace filter?
  • How do I know which filter is right for me?
  • How are filters measured?
  • What types of filters are there?
  • And finally, how much do they cost?

What is a furnace filter?

In an HVAC system air is collected from the home by a blower motor, either heated or cooled, and then recirculated throughout the house. A furnace filter removes impurities from the air before the air is conditioned. Changing your air filter on a regular basis will improve your indoor air quality, improve your health, reduce amount of dust and dander in the air, and help your HVAC system be more efficient


How do I know which filter is for me?

We like to say there are no one-size fits all solutions when it comes to HVAC. This holds true for your filters. A one-inch filter may work for one homeowner that wouldn’t be ideal for a family with allergy sufferers who need a higher filtration value.

Many factors go into which filter is right for you such as: the size of the filter in relation to your system. Check your furnace’s owner’s manual to determine the size and filter requirements and limits for your system.

Next, is the material that the filter is made out of. Some filters are made from inexpensive materials or use a crisscross pattern. While these often are cheaper they tend to provide less filtration.

Third, is the amount of airflow. Proper airflow is vital to any HVAC system. A clogged filter can lead to problems in the long run from being less comfortable in your home to a complete shutdown of your system. Lastly is the filter’s rating at how effective it is in removing particulates from the air.

How are Filters Measured?

An air filter’s effectiveness and quality is often associated by two ratings. First is the Clean Air Delivery Rate, or CADR. This rating is the amount of airborne particles that can be removed from the flow of a set volume of air per minute. Simply put, the higher the number the more effective the filter is at removing particles from the air.

Next, is the MERV rating or Minimum Efficiency Reporting Value. This rating measures a filter’s ability to capture particles based on their size. The MERV scale goes from 1 to 16 with a MERV rating of 1 being able to filter air particles between 3-10 microns. A MERV rating of 16, however, can capture particulates between .3 and 1 microns.

What types of furnace filters are there?

First are your entry level filters. These are normally your thinner, one-inch filters you find in many box stores made of fiberglass material. Typically, they have a MERV rating between 6 and 8.

Next up are the mid-range filters. Generally speaking, these will be thicker, 4-inch filters with higher CADR and MERV values. With mid-range filters expect a MERV rating around 10 to 12 and a CADR rating at 200 or more.

Although high-end furnace filters aren’t much larger than mid-range options they do come with more filtration. A high-end furnace filter will come with a MERV rating up to 16 and a CADR rating up to 1,200.

Lastly are electric filters. Even though they are less popular they can be very effective at cleaning the air with up to 700 CADR.  However, electric filters are known to produce ozone so you’ll want to make sure they are within safe levels. Fortunately, the best versions keep ozone levels to negligible levels.

Carbon filters can also be added to an HVAC system to provide additional filtration from smoke, cooking odors and pets. However, you’ll want to be careful the insert doesn’t restrict too much airflow. Too much restricted airflow can result in increased static pressure which could lower the life of your HVAC system as a whole.

How much do they cost?

All of this sounds great but how much do they cost? Entry-level filters, like the ones you’d see in department stores, typically cost less than $30 and will need to be replaced every 30 days. Your mid-range filters will range between $50 and $100 depending on the level of filtration you’re looking for. These typically last longer too, needing to be changed out only a couple times a year. With high-end filters some are washable and have a higher initial investment to be installed to your HVAC system. With installation expect to pay around $1,500. I know it’s difficult to fathom spending that much money on a filter. But it’s both higher quality and can last 10-15 years, easily saving you $100 per year in replacement filter costs.

Let’s talk about what to do next. If you’d like to learn more about filters and indoor air quality visit our website’s filter page. There you can check out additional resources on filters and other HVAC topics. You can also order filters directly and have them delivered right to your front door. Thank you for watching and we look forward to making your day even better!

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