Air filter maintenance can extend the life of your HVAC system, prevent repairs, and help lower energy costs — but how do you know when it needs changing?
This post will feature some common contributors to how often you should be changing your filters.
If you’ve recently changed your air filter and are still experiencing AC issues, check out Hurliman’s helpful guide on troubleshooting the problem.
Table of Contents
The number of pets in your home
Most people don’t realize the number of pets living in their homes can impact how often they need to change their air filters. Pets such as dogs and cats shed fur, dander (dead skin cells), and hair that accumulates quickly on an air conditioner’s filter, as well as tracking in additional contaminants like pollen and dirt.
It may aggravate respiratory issues for allergy and asthma sufferers — it is wiser to change it more frequently if your home includes one or more animals.
Utilizing filters with a high minimum efficiency reporting value (MERV) ratings will also aid you in maintaining optimal AC system performance. MERV eight and nine filters, for instance, are highly effective at trapping dust mite debris, large dust particles, mold spores and bacteria while filtering out most smoke particles and finer particles that cause allergies or asthma symptoms.
If you don’t have pets and don’t suffer from allergies or asthma, filter changes may only need to take place every six months. But if you live with multiple animals, more frequent filter replacement may be required — every three to six weeks for optimal air quality and extended system lifespan. Switching out filters regularly is inexpensive and will improve indoor air quality and comfort.
The number of people in your home
The number of people living in your home can significantly impact the frequency of air filter changes. More people entail more impurities captured by the filter, which may cause it to clog faster. Below are some reasons detailing this:
- Increased debris: The more people in a house, the more dust, dirt, and debris are brought into the home. This can come from the outside on our clothing and shoes or through open windows and doors.
- Skin flakes: Humans naturally shed skin flakes, which can accumulate in the air filter over time.
- Activities: Cooking, cleaning, and other daily activities can release particles into the air, which the filter needs to capture.
If you live alone, you might want to change your filter every 2-3 months. For an average family of four without pets or allergies, changing the filter every 30-60 days is recommended. However, if there’s a smoker in the house or someone with allergies, it’s advisable to change it even more frequently — every 20-45 days for optimal air quality.
The type of filter
Filters have varying lifespans and effectiveness in trapping particles. Filters come in various varieties and, thus, will affect how often they should be changed out. Here is an overview of different filter types as well as how often they need replacing.
Fiberglass filters
The cheapest and most basic filters — fiberglass filters — are designed for HVAC protection rather than improving air quality and typically have shorter lifespans, usually needing replacement every 30 days.
Pleated filters
Up a notch from fiberglass filters, pleated filters are more effective at capturing smaller particles like dust mites and pet dander, which makes them a better option for improving air quality. These filters can last up to 90 days before needing replacement.
Electrostatic filters
These filters use self-charging fibers to attract and trap particles. Electrostatic filters are more effective at trapping smaller particles compared to pleated filters, hence improving air quality significantly. They are typically replaced every 30-60 days.
HEPA filters
High-efficiency particulate air (HEPA) filters are considered the gold standard in air filtration. HEPA filters can trap 99.97% of particles as small as 0.3 microns — including most allergens, dust mites, bacteria and viruses — however, their use should only be recommended by your HVAC manufacturer to ensure sufficient airflow is preserved. These filters typically need replacement every 12-18 months.
Washable filters
Reusable filters offer both cost and environmental savings; they can be washed and reused again after cleaning, making them cost-effective and eco-friendly options. It is important that they be dried thoroughly prior to installation in order to prevent mold growth. Replacement can vary from 1 to 5 years, depending on use and maintenance.
The level of local pollution
The environment can have an enormous effect on your filter’s lifespan. For instance, its durability depends on factors like its surrounding air quality — heavily traveled roads could make for dirtier filters; construction might create further dust.
If you live in a mild climate with only light usage of furnace and AC units, one filter could last several months up to an entire year. However, in large homes with multiple people living inside, it might need replacing more often.
As a general guideline, inspecting and replacing your AC filters at least every three months is advisable. This timeframe may differ depending on how often you use your system and the amount of dirt in its surroundings. Doing this will help protect against costly repairs and property damage to prevent an unexpected breakdown.
