Getting Started: What Are Air Filters and Why Do They Matter?
It’s important to choose the best air filters for a home. Home air filters (also called furnace filters) keep the coils and heat exchangers on the heating and air conditioning system clean. When those pieces get dirty, the system must work harder. Changing the air filter regularly will help prolong the life of your heating and air conditioning unit.
The filter in your heating and air conditioning unit also helps clean the air you and your family breathe. The variety and number of particles in your home’s air depend on many factors, including how many people and pets are in the house and what kinds of activities occur there. People with allergies or asthma should be extra diligent about replacing their house air filters regularly.
Each type of filter for HVACs can capture specific particles such as:
Some air filters can trap more pollutants than others. To find the best air filter for your home’s needs, you’ll need to understand filter efficiency, which we’ll discuss in the next section of this guide.
MPR Ratings vs. MERV Ratings for Air Filters
So, what are MPR ratings for air filters? And are they the same as MERV ratings? The performance of the filter is affected by the size and density of the material and is measured by the size and volume of the particles it’s able to filter. The industry standard for air filter efficiency is indicated by the Minimum Efficiency Reporting Value (MERV). The Filtrete-brand standard for air filter efficiency is indicated by the Microparticle Performance Rating Value (MPR). MPR was designed to measure the capture of more microscopic particles and exceed the industry standard. Efficient filters have higher MERV ratings or higher MPR ratings. The least-expensive filters have a layer of fibers that trap only basic particles. Simply put, if you need a filter that captures more particles, a higher MERV/MPR rating is necessary.
Here are some commonly used MERV ratings for air filters:
A smart air filter has a built-in sensor that works with a mobile app to monitor the life of the filter.
Home Air Filter Sizes, Types, Shapes, Materials and Styles
Before purchasing a new air filter, verify the filter size you need by checking the existing filter’s dimensions. Most furnace filters for residential heating, ventilating and air conditioning (HVAC) systems are 1-inch thick, but some homes require up to 4-inch filters because of the volume of air circulating in the home.
When it comes to purchasing an air filter, there are several choices of materials and styles to choose from. Here are some of the most common types of filters:
- Pleated filters are more efficient because the pleats provide a greater surface area to trap particles. Many pleated filters are electrostatically charged to help them attract and hold microscopic particles.
- Adjustable filters are available for nonstandard ventilation openings. Extended filters sizes are also available for room air conditioners, register vents and return vents in the floors, walls and ceilings.
- Reusable filters are made of material that can be cleaned according to the manufacturer’s specifications.
Home Air Filters vs. Air Purifiers: What’s the Difference?
A home air purifier isn’t another type of air filter. Instead, it’s a small fan-like appliance that filters pollutants, allergens and toxins inside a certain area of the home. Given the concern over indoor air quality, the popularity of home air purifiers is increasing.
Which air pollutants are removed from the environment depends on the type of purifier purchased. Some air purifiers have filters that trap the particles as the air passes through them. Others may diffuse air particles without filtering them first. Regardless of which type of air purifier you use, it will work best when combined with regular household cleaning, like dusting and vacuuming, to help remove harmful particles from the home.
Air purifiers come in a variety of sizes. A larger system is a good choice if you’re trying to clean the air in a sizable open space such as a living room. Smaller units can be used in individual bedrooms and other more confined spaces.
Air Filter Replacement
So how often should you change air conditioner filters? The replacement frequency can depend on factors like the number of pets in a household, the filter location, the home size, whether you have allergies and the season of the year. Although you should always defer to the filter manufacturer’s specifications for details, here’s some general guidance:
- Be sure to change all HVAC air filters at least every three months — even if they don’t look dirty — to keep your system running efficiently.
- Non-pleated filters should typically be changed every month,
- Pleated filters can often last up to three months.
For more information on changing your air filter, see our companion guide.
Recap: Key Takeaways
- Air filters keep HVAC systems efficient and improve indoor air quality.
- Filters can trap dust, pollen, mold spores, pet dander, smoke and bacteria.
- Filter efficiency is measured by MERV (industry standard) and MPR (Filtrete brand).
- Filter types include adjustable, pleated (the most efficient), and reusable filters.
- Replace filters regularly: monthly for non-pleated, every 3 months for pleated.
Frequently Asked Questions
Here are some of the most common questions users have when shopping for an air filter.
What Kind of Air Filter Do I Need?
The best air filter for your house will depend on your home’s HVAC system as well as the number of people and pets you live with. The article above can help you determine the recommended air filter for your situation.
What Is the Best Air Filter for Pet Hair?
Some air filters are optimally designed for removing pet dander from the air. Check the packaging on the filter you’re considering to see if it’s a good choice for pet owners.
