The Major Consequences of Not Changing Your Air Filter

For many people, changing the air filter on your HVAC system is an afterthought. It is an easy task that can easily be overlooked. But it is such an important task and should become part of your routine every couple months. A dirty filter will not clean itself, and leaving the screen in place sets the stage for a variety of problems. A few of those issues could affect your health as well as the life of your system.

HVAC systems have a life expectancy of around 10 to 30 years. Most homeowners can expect 10 to 20 as the sweet spot for a modern system. How long the unit ultimately lasts will depend on how often you have it serviced, and one of the most helpful things you can do in this regard is to replace the filters regularly.


How Do Air Filters Work?

Air filters are generally made of a spun fiberglass material or from pleated paper or cloth enclosed in a cardboard frame. They are inserted into a specific place in the HVAC systems and act as a barrier to prevent contaminants and other particles from circulating in the air, or from reaching sensitive parts of the system. Filters trap and hold many types of particulates and contaminants such as dust, pollen, lint, mold, hair, animal fur, bacteria and more.

Filtration usually occurs when expended air is brought back into the HVAC equipment to be conditioned and distributed again. The air is forced through the filter, and the material removes particulates and other contaminants from the air.

MERV Ratings and Filter Efficiency

Not all air filters will clean your indoor air with the same level of efficiency. Higher-quality filters, while costing more, will be able to remove more contaminants from your indoor air.

Filter efficiency and performance is often indicated by the filter’s MERV rating (Minimum Efficiency Reporting Value). Standard MERV values range from 1 to 16, with the number serving as an indicator of how well the filter will remove material from the air.

The higher MERV numbers indicate better filtration.

MERV Rating Average Particle Size Efficiency in Microns
1-4 3.0 – 10.0 less than 20%
6 3.0 – 10.0 49.9%
8 3.0 – 10.0 84.9%
10 1.0 – 3.0 50% – 64.9%, 3.0 – 10.0 85% or greater
12 1.0 – 3.0 80% – 89.9%, 3.0 – 10.0 90% or greater
14 0.3 – 1.0 75% – 84%, 1.0 – 3.0 90% or greater
16 0.3 – 1.0 75% or greater

HEPA (High Efficiency Particulate Air) filter is a type of pleated mechanical air filter. This type of air filter can theoretically remove at least 99.97% of dust, pollen, mold, bacteria, and any airborne particles with a size of 0.3 microns. The diameter specification of 0.3 microns responds to the worst case; the most penetrating particle size (MPPS). Particles that are larger or smaller are trapped with even higher efficiency.

How Often Should Filters Be Changed?

All air cleaners require periodic cleaning and filter replacement to function properly. Depending on the type of air filter you are using, you will need to follow different schedules to ensure that the filter is always functioning for optimal performance. Most manufacturers recommend that basic filters are changed every 30 to 60 days, but there are other circumstances that could affect that schedule.


  • A filter in a regular home with no pets should be changed every 90 days
  • If your home has a single pet, the filter should be changed every 60 days
  • For multiple pets, or if anyone in your home suffers from allergies, you’ll want to change the filter anywhere between 20 to 45 days
  • People in single-occupant homes with no pets, or those who own vacation homes that do not get much use, can usually wait for 6 to 12 months before changing their filter


What Happens When You Don’t Change Your Filter?

When air filters are not consistently changed, they get clogged by the buildup of particles and contaminants that stick to the filter. While the filter is designed to accommodate these minuscule items, the buildup creates an almost impenetrable barrier so that the air cannot completely flow through, which can ultimately cause multiple problems for the entire HVAC system.


  • Higher Energy Bills

The purpose of an air filter involves capturing dirt, dust, and similar debris. A dirty filter eventually becomes clogged. Clogs restrict airflow, which then causes the furnace or AC to work harder. Not replacing your HVAC filters regularly is going to increase the cost of your energy bills. That is because the unit has to work longer and harder to maintain the preferred temperature that you would like for your home.

A good sign that it is time to replace the filter is comparing your energy bills and behaviors from month-to-month. If you’ve noticed a 10 percent increase in your bill under the same usage patterns and temperatures, switch it out.


  • More Costly Repairs

HVAC maintenance, especially during the standard life-expectancy years of the unit, is pretty reasonable in terms of costs. However, failing to change out your filters can lead to all kinds of internal problems with the unit. Each one of these repairs might lead to hundreds of dollars in HVAC technician visits. All are avoidable if you just switch out the filter from month-to-month.

Here are some of the most common.

  • Frozen coils
  • Weird noises
  • Fuse failure
  • Tripping the breaker
  • Dirt buildup on your condenser


  • Poor Temperature Regulation

Since clogged air filters make the system strain to create airflow, warm or cool air cannot adequately go where it is needed. This means that some rooms could be too cold during the winter or too hot in the summer.


  • Health Concerns

If clogged, the filter will not be able to do its job properly. As a result, the ducts might become filthy, and excessive dirt and dust may filter through the house. Any impurities in the air may find their way into the lungs of people who are breathing. Common ailments include allergy irritation and respiratory challenges.

  • HVAC System Failure

Putting an excess strain on the furnace or AC eventually means consequences. Unable to handle the extra load, the system may break down. The breakdown could be permanent, meaning you need a new unit. If this happens, expect to spend thousands of dollars.


  • Furnace Failure

As the system is working harder to get around clogged air filters, it can cause the entire system to overwork and eventually break. If this happens, you will need to replace the entire system. This can range into the thousands of dollars. Air filters usually cost less than $40, so they are easy to replace frequently compared to replacing the entire system.


  • Clamped-Up Coils

Evaporative coils, which help remove heat from the air to keep your home cool, can freeze up if they are overworked. With a clogged air filter, the air won’t flow over the coils correctly, which makes them stop working and leads to total system failure. Again, the price to fix this issue is greater than simply purchasing a new air filter every few months. Protect your HVAC system and your wallet by replacing the air filters on a regular schedule.



What To Do

The bottom line is that HVAC systems perform better and last longer if they are properly managed. It is up to you as the homeowner to stay tuned in to your unit and take action if you notice any issues with rising costs, air quality, or overall unit behavior.

If you have not changed the air filters in your home lately, your next step should be to figure out which filters you need and replace them as soon as possible. If you find that the old filters look like nothing, not even air, could ever pass through them, it is time to contact an HVAC professional. An Aire-Tech professional can visit your house to inspect the system and resolve any issues caused by the clogged filters, thus preventing further problems in the future.



Final Thoughts

As the weather begins to warm up and winter starts to die away, it is important to take a few preventative measures to protect your home through the warmer months when windows start to open and birds begin to sing. Spring cleaning is generally a task that can be done relatively inexpensively, but will make a big difference in how comfortable your home is, and could end up saving you money on energy bills, too. In fact, many very effective home weatherproofing jobs are something that homeowners can complete without professional help.

If your system needs repair or inspection before winter, call Aire-Tech at 951-926-1002. You can also visit our Contact page and complete the contact form.