One of the essential maintenance tasks for your HVAC system is changing the filter regularly. Air filters keep the air around your home clean and help capture dust and other contaminants to prevent them from damaging your HVAC equipment.

Changing them regularly helps maintain the effectiveness of the HVAC system, prolong its lifespan, and increase its energy efficiency. However, you might sometimes forget to change your filter or not know when the ideal time is to do so.

Filters come in different sizes, types, and brands, and this impacts how soon you should change them. Generally, experts recommend that you change your filter after 3 months. However, the following factors could determine how frequently you actually choose to do it.

Size and Type of the Filter

There are various air filters like HEPA, flat-paneled fiberglass, pleated, and reusable filters that can be washed. They’re made using different technologies, and they all have distinct capabilities to trap different levels of contaminants. After buying your filter, look at the manufacturer’s instructions and the MERV rating to determine how often you should change it.

Depending on your HVAC system, you can buy air filters between 1 inch and 6 inches. Experts recommend that you change your 1- and 2-inch filters after 1 to 3 months, 3- and 4-inch filters after 6 to 9 months, and 5- and 6-inch filters after 9 to 12 months.

Presence of Pets

If you have pests, it increases the number of contaminants in the air because of the pet dander, which means that your filter clogs faster than it would in a house without pets. If you have one pet, you should replace your filter after 2 to 3 months, but you should change it monthly if you have more than one pet.

People With Allergies and Respiratory Diseases

Suppose you or any member of your family suffers from allergies or respiratory diseases triggered by contaminants like dust, pollen, or pet dander. In that case, you should change your filters approximately every 6 weeks. If you have pets, change them more frequently.

House Occupancy

If you are alone or only live with your spouse and have no pets, you can change your air filter after 6 months. However, if there are more people and pets in your residence, that increases the contaminants in the air, so you should change your air filters more often. If you have children, you need to ensure that the air is at its best, and you should change your filters after 2 to 3 months.

How Often You Use the HVAC System

In spring and fall, you hardly use your HVAC system, which means that its filters are less clogged and worn out. Consequently, you can go a long time without replacing them. However, during summer and winter, the HVAC system usually runs most of the time, which means it traps far more contaminants.

During those seasons, you should change your filter after 6 weeks. If you are operating a vacation home separate from your usual residence, you can replace the filter after a year because you hardly run the HVAC system.


The external environmental conditions also influence the indoor air quality of your home. If you live in a dry and dusty area or an area with high levels of other contaminants like pollen or smoke, you should change your air filters after every few weeks. However, if you live in a typical environment without many contaminants, you should change your filter after about 3 months.

Signs That You Need to Change Your Filter

Even after knowing the factors that influence how frequently you should change your air filter, you might forget to do it when the time comes. However, some signs will tell you when your filter is no longer effective.

One of the most obvious signs is not remembering the last time you changed the air filter. If you have gone for longer than the time indicated on the packaging, it means your filter is already clogged.

When you notice that the HVAC system is overheating or your AC is letting out warm air, it means that the air filter is quite clogged, preventing the circulation of clean air. That causes the HVAC system to overwork and consume more power, increasing your electricity bills and reducing the lifespan of the system.

Another sign you should be aware of is an unpleasant smell like a burnt or smoky odor coming from the HVAC system. When the warmth in the HVAC system meets with the dust in the air filter, it heats it, causing a burning smell.

Suppose you realize that you are having more severe allergies or worsening symptoms of respiratory disease. That probably means your clogged air filter is releasing dust into your indoor environment.

Finally, if you notice more dust around your air vents and the furniture close to the vents as compared to other parts of the room, it means the filter is clogged and allowing dust back into the house. You can confirm this by using the white sheet test in which you place a white sheet close to your vents. If the sheet turns gray, it indicates a dirty filter. The grayer the sheet, the dirtier the air filter is.

To ensure that you always change your filter on time, have a reminder on your phone or mark the dates on the calendar.

How to Change Your Filter

You do not need to call a professional to help you change your air filter. The first thing you need to do is purchase an air filter and ensure it’s the right size. Look and see if the old filter had the size printed on it. Alternatively, you can manually measure its depth, width, and length.

When buying an air filter, you need to ensure that the brand you are buying from is reputable. It would be best to buy from retailers who are verified distributors of trusted HVAC filter brands.

Turn off the HVAC system. To remove the old filter, you first need to find it. It’s usually in the air handler located in a dedicated closet, but it could be in a return duct. If the filter is in the HVAC system’s air handler, use a screwdriver to open the access panel. If it is in the return duct, flip the handles holding the grille and remove it.

Once you can access the filter, look at how it’s situated, take it out, and replace it with the new one. Finally, replace the cover or grille, and turn your HVAC system back on.

Benefits of Changing Your HVAC Filters

Aside from improving the efficiency of your HVAC equipment, prolonging its useful life, and avoiding the need for repairs, there are other advantages of staying on top of your air filter changes. You’ll find that your own health might also improve. The indoor air quality in your home will be enhanced, and you should sleep better.

Rely on Your Local Professionals

If you’re in the vicinity of San Marcos, you can turn to our experts at Oak Island Heating and Air Conditioning will all your HVAC questions and concerns. We’ve been assisting people in this part of California with their heating, cooling, and IAQ installation, maintenance, and repairs for over 20 years. Our NATE-certified technicians have a combined total of more than seven decades in the industry. We’re here to help you improve your indoor air quality and keep you comfortable in all seasons. Call us today to arrange a consultation.

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