Changing the air filter of an AC is a forgotten task for many. Still, an air filter is an essential part of all HVAC systems, and it’s in charge of the important job of trapping small dirt particles, harmful microorganisms, and more from the air circulating in a room.
How Do I Know If My Air Filter Needs Changing? (10 Signs)
As air filters purify most allergens, dust, dirt, and microorganisms from the air that circulates in your home. They will keep on doing it until getting clogged, so a reason for maintaining your HVAC system is to keep the air filter from clogging. But, if clogging does happen, there are some signs that will tell you it’s time for an air filter change:
- Dust gets accumulated on the fan blades and near the output vents.
- The air is not as cool as it was before.
- The AC takes more time to cool the air of the room.
- The AC system makes weird or excessive strain noises when starting.
- Some ACs have smart systems that notify you when the air filter needs changing.
- The AC is malfunctioning.
- The AC turns on and off frequently (short cycling).
- The people living in the house start to sneeze and have an allergy.
- Contamination, dirt, and dust build up in the duct.
- The electricity bills are higher due to the extra work and power the Ac needs to cool the air.
Checking the air filter to see if it’s dirty or clogged is easy. If you have any of the situations mentioned before, it should be done once a month to see if they need immediate replacement.
To check the air filter, you just need to remove it from your HVAC system from the air-handler and hold it up to the light. If you can’t see the light through the air filter, it means that it’s dirty or clogged and needs to be changed immediately.
Steps to Change My Air Filter
Whether you need to replace, clean, or just check the air filter, the process of changing the air filter is very straightforward. These are the right steps to follow:
- Turn off the HVAC system. You can turn your unit off completely using the circuit breaker.
- Locate the air filter. There are two places where the air filter can be located: the return duct or the air handler unit, which can be located in an attic, basement, or closet.
- Remove the grill or cover. If the air filter is in the air handler unit, you’ll need to open the access panel, and if it’s in the return duct, you’ll need to remove the grill. You’ll need a screwdriver for this step.
- Remove the old filter. Take the old filter out of its place and inspect it to know if it needs replacement or if it can be cleaned. If you were just checking, and the air filter is still in good condition, you don’t have to change it.
- Insert the new or cleaned filter. After checking the air filter, cleaning it, or replacing it, you can place it inside again, ensuring the airflow arrows are pointed into the unit. To buy a new filter, you’ll need to find one that matches the size of the old filter, which should be printed on the side.
- Put the cover or grill back on. After putting back the air filter and the cover or grill, turn the HVAC system back on to make sure the air filter is working properly, and the change was a success. Keep track of the date so you know when it’s time to recheck your air filter.
PartSelect has an amazing video that shows you in detail how to clean or replace the air filter of a wall-mounted AC unit and a portable AC unit.
What Happens If I Don’t Change My Air Filter?
The function of an air filter is to purify the air that’s circulating in your home. Air filters will trap everything from dust and pollen to harmful microorganisms and pet hair to keep the air you breathe free of these elements.
If you don’t change the air filter, these elements will keep building up in the air filter, as if you don’t check your email inbox and mails keep stacking up. This could lead to:
- Health issues. There are harmful particles in the air that can irritate your respiratory system, leading to coughing fits, a runny nose, sneezing, headaches, and itchy eyes. People that suffer from allergies and asthma are more vulnerable than others. And, inhaling these irritating particles over a long time could cause long-term respiratory problems, like chronic obstructive pulmonary disease (COPD) and pulmonary fibrosis.
- High energy bills. When the air filter is clogged, the HVAC systems need much more energy and power to cool or heat the room’s air, which means running for a longer time to get the job done, leading to high energy bills.
- System problems or failure. As the HVAC system works harder to pull the air through the clogged air filter, the continuous strain could lead to malfunctioning or even the system’s complete failure. This creates the worst-case scenario as you’ll need to get it repaired or replaced completely. Replacing the entire system can cost $4,000 to $10,000 or even more, which is really high compared to spending $40 that could cost the air filter replacement.
The Air Of Authority has a fantastic video where a specialist in the field talks about the consequences of not changing air filters and about the MERV rating.
What facts affect the right time to change the AC air filter?
The 90 days general rule to change the air filter can apply for ACs in homes with no pets, no kids, and low environmental contamination, but depending on some factors, this time could be shorter or even longer:
- The type of air filter you have. There is a wide range of air filters, and some are better than others. Fiberglass filters are cheaper and need to be changed every month, but other high-end pleated filters can last up to 6 months.
- Having pets. Pet owners know the struggle with shedding is real, and without air filters, the situation wouldn’t be even bearable. But this has a downside effect on air filters, making them last less. The recommendation is to change the air filter every two months if you own a pet.
- Allergic or Asthmatic people. If you are usually allergic or suffer from asthma or any other breathing issue, then the recommendation is to change the air filter every 6 weeks. The Allergy and Asthma Foundation of America (AAFA) said that indoor air can be as bad as outdoor air, and breathing high-quality air at home is essential for allergic and asthmatic people.
- Having children. With small children at home, you’ll want the air quality to be as high as possible to avoid any health issues, so the recommendation is to change the air filter every two months.
- The average time of use. Depending on how much you use the HVAC system at home, you’ll have to change the air filter more or less often. If you use the AC daily, the recommendation is to change the air filter every two months. Vacation homes don’t use HVAC systems frequently, so you can change the air filter of a vacation home every six to 12 months.
What Can Affect The Lifespan Of Air Filters?
Every air filter is different, and each of them has an expected lifespan indicated on the side of the packaging. But sometimes, the air filter needs to be replaced before the estimated time. The lifespan of an air filter can be affected by some factors such as:
- The size of your house. If you have a small house, the AC will need to blow less air to make the temperature change to the desired one, translating into not changing the air filter so often. On the other hand, in a big house, the AC will blow air continuously, clogging the air filter faster.
- How often you use the HVAC system. If you use your AC daily to keep your house cool all day every day, then the air filter will need to be replaced before expected due to it.
- Your house’s air quality. The lower the air quality you have inside your house, the more particles will get trapped in the air filter, meaning it will need to be changed sooner than expected. Pets also affect the air quality due to their fur.
Cleaning or Replacing My Air Filter?
Depending on the type of air filter you have and how dirty or clogged it is, you can decide whether to clean it instead of replacing it to make it last longer. From disposable air filters to washable and more durable ones, each has different specifications.
There are disposable filters designed for just a one-time use; they are less expensive, and their performance and purifying power are not of the best quality. These air filters usually have a cardboard frame that won’t stand the cleaning process, so they always need to be replaced.
But there are air filters designed to be washable that last longer and have a better performance than disposable ones; these cost more than disposable filters. Typically they have a metal or plastic frame that can stand the cleaning process, making them environmentally friendly as you don’t have to replace them that often.
How Do Air Filters Work?
The AC works by turning the air circulating in a room into the cold air, but it has to pass first through the air filter. The air filter’s job is to trap all the particles floating in the air like dust, pollen, dirt, mold spores, fibers, lint, wood particles, hair, animal fur, and microorganisms to keep the air you breathe clean.
But each air filter is different, and the level of substances it can purify from the air varies.
Some air filters are more efficient than others, and you can determine their efficiency by the MERV rating. The MERV rating refers to the minimum efficiency reporting value of each air filter, ranging from 1 to 20. The higher the air filter’s MERV rating, the more efficient it is trapping particles:
- Low MERV rating (1-4). These filters have the lowest efficiency and aren’t good at trapping small particles. They can filter out pollen, dust, and other particles larger than 10 microns.
- Medium MERV rating (5–8). These filters have better efficiency and can trap dander, mold, and particles as small as 3 microns.
- High MERV rating (9-12). These filters have a HEPA (high-efficiency particulate absorption) level. The EPA recommends having these filters at home. These filters can trap particulates as small as one micron.
- Extra high MERV rating (13-20). These filters are potent and can trap every substance and harmful particle as small as 0.3 microns from the air. They are not recommended for a house as they are expensive and usually not compatible with most HVAC systems. Typically, they are implemented in commercial HVAC systems, like in hospitals.
Hi there! My name is Giovanna, and I’m a Med Student from Venezuela. My not-so-hidden passion for writing and research led me to start working as a freelancer in 2016, and it’s been quite an exciting journey ever since. Speaking three languages (Spanish, English, and Italian) also contributed a lot by opening many doors for me in this field. I love to write my articles the way I would love to read them, engaging, full of interesting facts about the topic, and easy to follow, making them valuable for many people. I like my job as a freelancer because I get to try and learn new skills with each new job, so I’m always excited to start new projects and for what’s next.