Changing your HVAC system’s air filter is like brushing your teeth; it isn’t exciting, but you have to do it to maintain a healthy balance. While air filters are out of sight and out of mind, for the most part, there are still indications that you need to swap them out for a new one.
We’ve pulled air filters from systems that are clean as a whistle and dirtier than a sandlot. You can bet that these two groups have different ideas when it comes to HVAC maintenance best practices. But what if you just don’t know when to replace your air filter?
While the base answer is simple, there are a few key factors that play a role in determining how often you should change your air filter.
Factors that impact the frequency of need to replace an air filter include:
- Pets
- Allergies
- Smoking
- Respiratory conditions
- Air quality
- Usage
- Filter density
- Filter type
But first, let’s answer the broader question of when to change your air filter, so you can keep your HVAC system running smoothly and efficiently.
How Often Do I Need to Change My Air Filter?
The standard recommendation for changing your air filter is every 3 months. But you’ll also want to check up on your filter once a month to make sure you’re on track for that 3-month mark.
Every home is different, and while replacing an air filter every 3 months is the best practice, the reality is that your home might require more frequent replacement.
There are several factors that contribute to shortening the lifespan of an air filter. Take a look at some of the top factors and see if you match any of them. If so, it might be time to shake up your routine.
8 Factors that Impact the Frequency of Air Filter Changes
Not every extenuating circumstance will apply to you, but keep an eye out for anything that remotely sounds like it plays a role in your home. Be sure to account for minor details within the broader subjects.
For instance, air quality is a broad but impactful factor when it comes to when to change your air filter. Taking stock of nearby factories or refineries will be helpful in determining your environmental factors.
1. Pets
Starting with one of the most common environmental factors, pets play a large role in the longevity of an air filter. Your furry friend’s coat and dander can end up clogging air filters and reducing their efficiency, while the dander can also circulate throughout ventilation.
In this way, reducing efficiency means the system will have to work longer to reach your desired temperature, which can put unnecessary strain on your HVAC system.
Be sure to brush pets outside and check your filter regularly. The frequency of filter checks depends on how many pets you have running around the house.
For pet owners, it’s typically recommended that you check your air filter every month and replace it as needed. You may need to replace a filter before the recommended 3-month mark.
2. Allergies
If you or a family member suffers from chronic allergies, you’ll definitely want to keep a close eye on your air filter. Pollutants and other irritants can get clog up your air filter and make your home a nightmare for allergy sufferers.
This factor also ties back to pets since many people have dog and cat allergies that greatly affect their quality of life. Checking on your filter once a month can prevent buildup and ensure everyone who enters your home can breathe easily.
3. Smoking
Smoking indoors can wreak havoc on your air filter. For this reason, it is recommended that you remain hyper-aware of your air filter’s status. Nicotine and tar easily clog up air filters and can attract other particles like dust and dirt to compound the damage.
Because HVAC systems run throughout a home, it is important to make sure your filter is in good working order to minimize the amount of smoke circulated to other rooms and people in the house.
You'll likely need to check your air filter a couple of times a month to keep on top of maintenance. A high MERV-rated filter can decrease the effects of smoke.
The MERV scale rates filters based on the size of particle they can catch. A higher MERV rating means the filter can catch smaller particles, while a lower rating means the opposite.
Filters with higher MERV ratings (13-16) are more expensive and are often found in the medical field. But because the higher the MERV rating, the more restrictive they are on airflow, meaning you’ll need to replace them more frequently.
4. Respiratory Issues
If someone in your home suffers from a respiratory condition like asthma, changing out your filter is pivotal to keeping them healthy and comfortable. Like with smoking, you’ll want to check your filter a couple of times a month to make sure everything is looking its best for your family.
The alternative here is to grab a filter with a higher MERV rating. Getting a higher-rated filter ensures you’re blocking out as many foreign particles as possible. This is also ideal if you live near an active construction site, industrial district, or refinery.
5. Air Quality
As mentioned above, active construction sites, industrial districts, and refineries can all play a part in air quality. While these factors produce a somewhat static amount of pollutants, there are other factors that are less predictable that can decrease air quality.
If you live in an area like Nothern California that experiences frequent wildfires, you’ll need to check your filter more often due to poor air quality.
Poor air quality can also be tempered with a denser filter with a higher MERV rating. Still, there are unpredictable events that affect air quality, meaning you’ll need to check up on your air filter more often than the once-a-month standard.
6. Usage
A simpler factor that can lead to you having to replace your air filter more often is how much your household uses your HVAC system. Anything from family size to having one person home all day can greatly affect the mileage of your air filter.
With more people in the house, there is more body heat and more demand for cooling in various rooms of the house. If even a single family member is home all day, the HVAC system will be working hard to keep the house heated or cooled.
Taking stock of how much your family demands from your HVAC system will help you gauge the frequency of replacement. Start by checking your filter once a month and then adjusting your schedule based on how your filter looks.
If your filter looks gunked up with dirt, it’s a good sign you should check more often. This will vary from household to household, though.
7. Filter Density
MERV ratings have come up a few times now. While a higher MERV rating means a filter can catch smaller particles, it also means the filters have a higher density.
The higher the density of a filter, the more often you’ll likely need to replace it. Filters with higher MERV ratings restrict airflow and will need to be swapped out more than usual.
MERV ratings of 1-4 are generally seen as less than and provide little in the way of filtration. Moving up the scale, 5-13 are considered for home use, but you really want to land a filter from an 8-13. Hospital-grade filters include anything from the 13-16 range, while cleanrooms and power plants often use 17-20.
Stick to the sweet spot of 8-13 when choosing a home air filter. Anything else might be overkill based on your needs.
8. Filter Type
There are several main types of HVAC filters:
- HEPA filter
- UV filter
- Pleated filter
- Fiberglass filter
- Electrostatic filter
- Media filter
Each filter has its benefits, and each of them varies in terms of longevity. For instance, filters like fiberglass ones are disposable and will need to be replaced more often than a reusable filter like an electrostatic one.
Aside from standard types of filters, UV filters are another consideration to factor in. These aren’t the main air filters, but they add another layer of filtration for bacteria and viruses.
You’ll want to double-check what filter type you have to determine the frequency in which it needs to be changed.
When Will You Check Your Air Filter?
We talked about plenty of factors that can impact how often you change your air filter. While the standard is to change a filter out every three months, there are a number of reasons to increase or decrease the frequency of maintenance. Everything from pet dander to smoke and filter types can have an effect.
Now that you know what to consider when deciding how often to change your filter, you can rest easy knowing you have a set schedule in mind.
After servicing many homes in Southern California, we recognize that everyone’s needs are different. When to change out your filter is no different. While we recommend checking up around the three-month mark, you may find that you can get by every six months, depending on filter type.
Changing out air filters is just one part of keeping your system healthy. You’ll also need to check up on when you should have your HVAC system serviced to keep it running reliably over the years. There are also plenty of steps you can take to ensure your HVAC system is running as efficiently as possible.
