Most people give little thought to their HVAC furnace filter. At most, people might only think about their filter when their maintenance schedule states it should be replaced. However, your furnace filter is a workhorse that has several important functions. Here is what your furnace filter does and why it’s important.

What Is a Furnace Filter?

Heating, ventilation, and air conditioning (HVAC) systems have blower motors that collect air from the home. With a furnace, the blower motor collects air to heat it. The furnace filter traps and removes dirt, pollen, allergens, debris, and other small particles from the air before it is conditioned. Furnace filters help to prevent debris and dirt from building up inside your HVAC system, and they also reduce contaminants that are released into the indoor air.

Location of a Furnace Filter

The blower compartment of your furnace houses the furnace filter. Typically, the filter will be contained inside a door or tray in your furnace’s blower compartment. Air blowers are normally located close to the air intake vents. Since furnace filters need to be changed on a regular schedule, it’s important to know where the filter is located and how to access it.

Furnace Filter Purposes

A furnace filter traps contaminants in the air. This helps to keep your indoor air clean, but your filter also has another critical function.

The main purpose of your furnace filter is to trap debris, dirt, dust, and other contaminants to prevent them from accumulating in your HVAC system. The function filters perform also helps to improve indoor air quality as they trap contaminants.

A furnace filter has a nearly identical function to an air conditioner filter. However, they work with heated air instead of cooled air.

The following are important functions of furnace filters:

  • Collects and traps contaminants
  • Prevents clogs
  • Increases heating system efficiency
  • Protects furnace from debris
  • Extends the lifespan of the furnace
  • Helps to prevent breakdwons

Lifespan, Rating, and Cost of Furnace Filters

The lifespan of your furnace filter depends on its thickness. Thicker furnace filters last longer, while standard filters with a thickness of 1″ to 2″ should be cleaned or replaced every one to three months. The effective lifespan of different furnace filters by thickness includes the following:

  • 1″ to 2″ – One to three months
  • 3″ to 4″ – Up to nine months
  • 6″ – Up to 12 months

Furnace filters also have varying levels of filtration as classified by a minimum efficiency reporting value (MERV) rating. Most furnace filters for residential HVAC systems have MERV ratings ranging from four to 12.

Furnace filters range in price but are generally inexpensive. Most cost less than $25, but some are as little as $10 to $15 per filter. Thicker filters and those with higher MERV ratings are more expensive than thinner filters and those with lower MERV ratings.

What Happens if You Don’t Change Your Furnace Filter?

If you fail to have your furnace filter changed regularly, several issues can arise. A dirty furnace filter can cause problems with the functioning of your furnace, cause your system to wear out faster, make your home less comfortable, and reduce the quality of your indoor air.

Damage to Your HVAC System

Furnaces contain multiple delicate components. If the air your system collects is not properly filtered, dust, hair, dirt, and debris can get into the various compartments of your furnace and accumulate. When accumulation occurs, the equipment’s performance will be negatively affected, and the components can be damaged.

A clogged filter means the air will not move through your furnace properly. The clogged filter will prevent the air from moving through its path, forcing your furnace to spend more energy to move it along for heating. The extra effort required by your furnace places stress on its components, causing it to use more energy and parts to wear out.

When the airflow is blocked by a clogged filter, the temperature of the furnace can go up and cause the equipment to overheat. The system will then cool before restarting and repeating the cycle. This leads to short cycling, which can cause damage requiring repairs and early failure. Short cycling also increases your furnace’s energy consumption and leads to higher heating bills.

Reduced Comfort and Poor Indoor Air Quality

Since an unchanged, clogged furnace filter restricts the airflow, this means the living spaces of your home will not receive the appropriate amount of heat. It can become more difficult to maintain your desired comfort level, and you might notice cold and hot spots in your home.

When your filter is clogged with contaminants, it will no longer have any remaining surface area to trap additional contaminants in the air. As a result, those contaminants will stay in your indoor air and cycle back into your home. This can cause respiratory issues, bodily irritation, allergy symptoms, and dirty surfaces that persist despite your cleaning efforts.

Changing Your Furnace Filter: Factors That Impact the Frequency

Changing your furnace filter should be included in your regular furnace and HVAC maintenance schedule. How often your furnace filter might need to be changed will vary based on its thickness. However, some additional factors could also affect the frequency of how often your filter should be changed.

How Many People Live in Your Home

How many people live in your home can affect the frequency of furnace filter changes. If you have a large household, you’ll likely need to change your filter more often. This is because many contaminants are introduced by people. If you have more people in your home, you can expect there will be more contaminants released into the air that your furnace filter will need to trap.

Whether You Have Pets

Pets contribute numerous airborne contaminants, including pet dander and hair. If you have pets, the dander and hair they release into the air will be picked up and circulated throughout your home. The filter will need to trap those additional contaminants, and the service life of the filter will be reduced. Having pets means you will need to change your furnace filter more often.

Whether Anyone Has Allergies

If any family member has asthma or allergies, you should have your furnace filter changed more often. This helps to reduce symptom-inducing contaminants in your home.

The Quality of Your Indoor Air

If you have an older home with air quality issues, your furnace filter’s useful lifespan will likely be reduced. Having other indoor air quality equipment like air purification systems can improve your indoor air quality and reduce the frequency of changing your furnace filter. By contrast, if you have air quality issues and only have your furnace filter as your sole line of defense against contaminants, the filter will clog and need to be replaced faster.

How Much You Use Your Furnace

How often you use your furnace also affects the frequency of necessary furnace filter changes. If you operate your system all of the time, the filter’s life will be shortened. This is because the air will be circulating more often, giving the filter more opportunities to trap debris and become clogged. Because of this, you can expect to change your furnace filter more often during the colder months.

Talk to Our HVAC Professionals

Properly maintaining your furnace requires more than paying attention to your furnace filter. It’s essential to work with our expert HVAC technicians to ensure your furnace is functioning properly and extend its useful lifespan. We offer comprehensive HVAC services, including furnace installation and repair, furnace maintenance, AC installation and repair, AC maintenance, and indoor air quality services. To learn more, contact Agers Heating & Air Conditioning in St. Peter, Missouri today!

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