Your filter may be the last thing on your mind almost every day of the year. However, when it isn’t there, is too clogged to work properly, or has rips and tears in it, you will know. We think of furnace filters as a low expense to help keep the insides of our HVAC systems cleaner.
While this is part of their job, the furnace filter is one of the most crucial parts of the entire system. They are also the easiest to maintain and replace. This article will offer you the best furnace filters, reviewed and compared for your convenience. We will also explain how furnace filters work, their various types, and give you the important factors to consider before you buy.
When Is It Time for a Filter Replacement?
The first job of a furnace filter is to prevent dirt, dust, and debris from entering the air handler. Instead of the interior of the furnace building up with gunk, the filter stands in the way. Over time, the filter material will get clogged with these particles and debris and start to prevent proper airflow.
When this happens (or better yet, before it happens), you should replace your filter with a new one. The life span of a furnace filter will vary from brand to brand and will depend on the filter material. The average lifespan of a filter will generally be 30, 60, or 90 days.
Benefits of Using a High-Quality Furnace Filter
Besides helping to keep the inner workings of the HVAC system clean, furnace filters have other benefits. High-quality filters will be more expensive, but the better quality gives you benefits that the cheaper models don’t.
For starters, most high-quality filters will be HEPA rated. This means they capture particles 3 microns and higher, thus eliminating up to 99% of in-home allergen causing microorganisms. This list includes mold, mildew, pet dander, dust mites, and pollen.
Other models add to this and increase the protection to include particles down to 2 microns in size. This adds bacteria and particles from coughing and sneezing to the list, further reducing the number of allergens and microbes in the air of your home.
Cigarette and cigar smoke, pollutants, chemical odors, and other airborne particles are also captured. When used properly, these high-quality filters can leave the air in your home pure, clean, and allergen-free.
Furnace Filters Compared
Furnace Filter Buying Guide
Before you head out and buy any old furnace filter, there are several things you need to be aware of. Most of the items listed below will be significant factors in your decision of which filter to purchase.
Further in the article, I will cover all the filter types in more detail. For this section, what you need to know is that you have a choice. Paper and fiberglass filters are some of the most common. They are also some of the most economical.
Your other choices include disposable, carbon or charcoal-activated, washable, and electronic filters. You can see below the reviews for more details on these various types of furnace filters.
Compatibility with Furnace
Some filters are specifically designed for certain furnaces. While you may find one that fits, if you don’t use the proper one, it could void your warranty.
Most air handlers are universal, and you won’t have to worry about compatibility too much. However, before you make a final purchase, you should check with your HVAC manual to ensure you get the proper one, or if a specific type, model, or brand is required.
Every filter has a Minimum Efficiency Reporting Value (MERV). This number rating system lets you know how well the filter material works. The higher the number, the better the filtration.
For residential systems, the MERV rating will fall at or below 13. Hospitals, doctors’ offices, and surgery clinics will use filters with a MERV rating between 14 and 20 (20 is the highest MERV number).
Along with the MERV number, you will also find the MPR number. MPR stands for Microparticle Performance Rating. This time, instead of an overall filter rating, the MPR measures the particle size that the filters allow through.
Like the MERV rating, the higher the MPR number, the better the filter is at capturing microparticles (those below 3 microns). The higher the MPR, though, also makes a filter more restrictive. You want the right balance for the particle capture versus airflow for your system. If your system works too hard to get air, it can burn out or become ineffective.
Furnaces and HVAC systems use different sized filters. While most of the filters you use will be 1-inch thick, the height and width will change. Usually, the filters are square, so the height and width for each application are the same (24×24, for example) Sizes range all over the place, and your home may even use multiple filters of different sizes.
Before you make a purchase, you need to know the correct size. If you buy the wrong size, it may not fit at all or can be too small to be effective.
Ease of Installation
The furnace filters install differently, as well. Some slide into a slot in the furnace housing, others are located in a wall or ceiling near the HVAC system. Look for your intake vents to know where your filters are located.
Wall filters will generally have a set-screw holding the grating in place. When you remove the screw, the grate will open outward to access the filter. Ceiling grates may also have set-screws but generally have thumb tabs. Push the tabs outward to unlock the grate and pull down to remove the filter.
Price & Warranty
Finally, you will want to note the price of the filter. Just because a filter costs more, doesn’t mean it isn’t a wise investment. A $10 filter that lasts for 90 days is a better alternative than a $5 one that is rated for 30 days.
Unless you buy a washable or electrostatic filter, most will not come with a warranty. However, it never hurts to look for a warranty on the packaging, which may help you in the event the filter material is torn or damaged when you get it home.
9 Furnace Filters Reviewed
Below we look at the 9 best furnace filters, reviewed and compared for your benefit. Even if you have a favorite brand, things can change. Find your next furnace filter on the list below and breathe easy.
1. Filtrete – Our Top Pick
|Sizes Available||1”, 4”, 4” slim and 5”|
|Brand Compatibility||All residential HVAC systems|
|Recommended Change||3 months (1-inch) 12-months (4-inch)|
Filtrete is a well-established household name in the air filter market. They have produced some of the finest filters at affordable prices for decades. The anti-allergen MERV 11 filters are no different.
These disposable filters are pleated fiberglass with a tight-woven material that captures in-home allergens down to 3 microns. Covering pollen, dust mites, pet dander, and mold and mildew spores, the best Filtrete furnace filters will help you breathe easier with the heat on or the air conditioner blowing.
This model features the most common residential sizes, including the standard 1-inch filter, along with both 4-in and 4-inch slim styles and the larger 5-inch thick versions. Finding the right size for your system is crucial for a good fit. Measure your filter housing properly as Filtrete doesn’t list exact measurements.
The nominal measurements, for the most part, are ¼-inch off (15 ¾ instead of 16, for example), so if your exact measurement is more than 1/4-inch off, you may find that you have a loose-fitting filter.
- MERV 11, MPR 1000 ratings
- Fits any residential HVAC system
- Reduces airborne allergens by up to 99%
- Filtrete doesn’t mark the MERV ratings
- Might be a loose fit if exact measurements are off
2. AprilAire 213 – Best Furnace Filters For Allergies
|Sizes Available||1 size only (4-inch)|
|Brand Compatibility||Aprilaire 1210, 1620, 2210, 2216, 3210, 4200|
The AprilAire 213 filter is a pleated filter rated at MERV 13 to catch not only allergens but also odors. This model will fit several AprilAire HVAC systems, including the 1201, 1620, 2210, 2216, 3210, and 4200. If you have the Space Guard 2200, this filter will also fit with the upgrade kit.
The best furnace air filters for allergies are self-healing, which means that the edges and sides will move to create a better seal, minimizing air bypass. The result of this process can make the edges of the filter appear bent or damaged, though this is normal inside the filter’s case.
The 213 is the higher rating of the 210 model, which can be used in the same systems as the 213. The difference is the MERV rating, with the 213 better (MERV 13) than the 210 (MERV 10) at capturing allergens and trapping odors.
The filters are rated for 12-months without replacement. They aren’t washable, but the 4-inch thick pleats allow for more airflow even when full of contaminants and debris. Those living in climates that attract more dirt and dust or sand will need to change the filters more often, but 9-months isn’t unreasonable.
- Self-healing filter prevents air bypass
- Captures allergen particles as well as odors
- Fits in multiple AprilAire systems
- Some filters are glued to the frames which can come undone during use
- Only suitable for AprilAire Systems
3. Lennox Healthy Climate – Best Air Filter For Lennox Systems
|Brand Compatibility||Lennox, Honeywell, Carrier, Trion Air Bear|
|Recommended Change||6 months|
The best filter for your Lennox system is the Lennox Healthy Climate. This is also the best furnace filter for your Honeywell, Carrier, or Trion Air Bear system that uses a 5-inch filter. One thing you will need to do is measure your filter for an exact measurement.
The nominal measurement of these filters is 20x25x5 inches. However, the exact size is 19 3/4×24 3/4x 4 3/8. The 3/8 inches on the depth measurement can cause loose fits in true 5-inch systems. If you have a 4-inch system, the fit will be too tight without compromising the integrity of the filter.
With a MERV rating of 11, the filter will capture most in-home allergens, including dust mites, pollen, and pet dander. Some smaller particles like viruses and bacteria will get through, though. For those of you that have severe allergies, you may want to upgrade to a MERV 13 filter.
There is a lot of airflow through these filters, with the pleats being larger and further apart. However, because there isn’t as much filter material as other 5-inch pleated models, you need to change them more frequently. Instead of the 9 to 12-month life expectancy of most 5-inch models, the Lennox Healthy Climate filters only last 6 months.
- Made in the USA
- Brand name Lennox also works with Honeywell, Carrier, or Trion Air Bear
- Comes with a MERV 11 filter
- Can have a loose fit in true 5-inch systems
- Doesn’t last as long as most 5-inch models
4. Genuine Bryant – Best Air Filter For Carrier Furnace
|Brand Compatibility||Bryant, Carrier, Payne, Totaline and Day & Night|
The best air filter for Carrier furnace systems is also made for Bryant systems. The Genuine Bryant filter is a 4-inch MERV 15 filter that is pleated for increased surface area and better filtration of microorganisms.
The MERV 15 rating is not designed for all systems and can impede airflow in systems not designed for higher filtration methods. You also need to take exact measurements if you are switching brands as the nominal measurements don’t hold to standard. The box measurements read 20x25x4.
However, instead of rounding up, the length measurement rounds down. The exact sizes are 20 5/8x 24 1/2×3 5/8. In standard orientation, the nominal measurement should be 21.
When installed, the filter will last up to a full year (depending on use and environment). It will capture all in-home allergens, including dust mites, pollen, dander, mold, and mildew. The filter will also clear odors and capture bacteria and fungus.
- MERV 15 is hospital quality filtration
- Fits most Carrier, Bryant and Payne systems
- Captures allergens, odors, bacteria, and fungi
- Doesn’t fit all models as nominal measurements are different than standard
- May impede airflow in light-duty systems
5. AIRx ALLERGY – Best 1 Inch Furnace Filters
|Brand Compatibility||Most 1-inch residential systems|
|Recommended Change||3 months|
AIRx Allergy filters are pleated 1-inch filters designed to replace Filtrete filters. AIRx anti-allergen filters reduce in-home allergy causing microorganisms such as mold, pollen, and pet dander. The MERV 11 filters can capture some cigarette smoke, but by nature are not odor-reducing filters.
The 90-day filters will not impede airflow and have a reinforced cardboard frame to prevent warping or collapse. You will find that the filters fit most residential fittings, including 14, 16, 18, and 20 inches in many lengths, including 14, 16, 18, 20, and 25 inches.
While AIRx doesn’t have the clout behind it that Filtrete does, the name is gaining in popularity. The filters a high-quality and will last the full 90 days (depending on environment and usage). Also, like Filtrete, the filters are inexpensive, though not quite so readily available.
You will also find that per inch, the AIRx filters offer more pleats for a larger surface area, better airflow, and more particle capture. While they may not have the brand recognition of Filtrete just yet, but they are growing. Within a few years, you may well see AIRx outselling Filtrete based on quality and durability alone.
- High-quality at low price
- Fits most residential 1-inch systems
- More pleats for more airflow and surface area
- Can be difficult to find in stores
6. FilterBuy AFB – Best Furnace Filters For Homes With Pets
|Sizes Available||1, 2, 3, 4, and 5 inches|
|Brand Compatibility||Most residential and commercial HVAC systems|
|Material||Synthetic cotton material|
|Recommended Change||3 months|
FilterBuy AFB filters have a MERV rating of 8, which is HEPA rated to capture pollen and pet dander. The lower MERV and MPR rating allows more airflow without damaging air quality or causing the HVAC system to work harder.
If you have pets, the AFB from FilterBuy is the best furnace filter for dog hair. Pet dander can cause allergic reactions or breathing difficulties. This MERV 8 filter will help capture that pet dander and prevent it from blowing around your home when the air turns on.
The filter comes in a lot of sizes, making it ideal for most residential applications. You will find that the average sizes are available from 14 inches through 20 inches. The larger sizes (30-inches or more), as well as the smaller sizes (10 or 12 inches), are not readily available.
If you want to control odors or minimize fungus and bacteria, these filters won’t work. You will need at least a MERV 11 filter for that. However, for everyday filtration with help in eliminating pet dander and most in-home allergens, there aren’t many better choices available.
- MERV 8 reduces in-home allergens and pet dander
- Lowers the risk of respiratory difficulties
- Beverage board frame is strong and durable
- Doesn’t come in all residential sizes
- Doesn’t capture odors or bacteria
7. Nordic Pure – Best Furnace Filter For Dust Control
|Sizes Available||1-inch (16-inch length)|
|Brand Compatibility||Any residential system|
|Recommended Change||Up to 3 months|
The best furnace filter for dust control is the electrostatic charged Nordic Pure. With a MERV rating of 12, it will capture allergens, bacteria, pollen, and odors. The electrostatic charge on the cotton fibers will catch and contain bacteria and fungi, preventing it from running through your HVAC system and into the air you breathe.
It will also capture cigarette smoke and other chemical odors. The 1-inch filters have a nominal measurement of 16 inches in length and width. The exact measurements are a half-inch shorter on the length and width and only ¼ inch on the thickness.
The lifespan of these filters is rated to 90 days. However, most users find that because of the extra capture ability with the electrostatic cotton and the tighter weave for the MERV 12 rating, most replacements need to be done monthly.
The 6-pack is relatively inexpensive, giving you between 6 and 12 months of filtering ability. Depending on your usage, you can extend a single purchase to two years in the right conditions. You may find that in the spring and summer, though, that you go through the filters at a higher rate (30 days) than in the winter months (90 days).
- High filtration value, trapping bacteria and fungi
- MERV 12 meets MPR 1500 rates
- Captures smoke and odors
- May need more frequent changes
8. Aerostar – Best Furnace Filter For Asthma
|Sizes Available||1 to 5-inches|
|Brand Compatibility||All residential and commercial applications|
|Recommended Change||2 months|
Respiratory issues are no fun. Asthma, bronchitis, even mild hay fever can make a second feel like an hour when you are trying to breathe. The best furnace filter for asthma is the Aerostar filter with a MERV 11 rating.
The deep pleats allow proper airflow while collecting and containing particles that can trigger asthma attacks. Other allergens are also contained in the fibers, including pet dander, pollen, dust mites, and mold spores.
The filter comes in all sizes, including the smaller 12-inch filters and larger 25-inch filters. The range of applications rivals our top pick, the Filtrete brand. Most residential systems, including those with a 5-inch filter width, will find an Aerostar filter to fit.
The nominal and exact measurements are the standard half-inch difference with a 1/4-inch difference in depth. Some applications will find a tighter fit than most other brands as the edge of the cardboard frame doesn’t always line up when glued.
These small nuances aside, the brand is reliable, though they aren’t the cheapest in the market. You can find a better build quality for a lower price, but rarely in a 6-pack that will last you two years.
- Reduces asthma triggers in the air
- Deep pleats for more airflow
- MERV 11 reduces other allergens in the home
- Not the best build quality
- Nominal measurements may be off between each filter
9. CAS 5-Stage – Best Washable Furnace Filter
|Sizes Available||14×25, 16×20, 16×25, 20×20, 20×25, 20×30, 24×24 (all 1-inch)|
|Brand Compatibility||Matches all furnace and air conditioners with 1-inch slots|
If you are looking for the best permanent filter, the CAS 5-stage electrostatic filter is your answer. This filter has a lifetime warranty and can be washed with soap and water, garden hoses, or other hand-washing methods.
The electrostatic filter is the only lifetime filter with a MERV9 rating (as of this writing) and will capture most in-home allergens. It will not be able to capture bacteria or fungus as the MPR rating is too low. However, for everyday air quality and a onetime purchase for the life of your furnace, there isn’t a better choice.
The electrostatic charge that captures the contaminants is self-created. As air moves through the woven material, the charge builds. When you wash the filter, the charge is removed, and the pollutants are washed away. When the filter is put back in service (about 20 minutes after washing to air dry), the charge will rebuild.
It is recommended that you wash the filter at least monthly. Though this can be done at any time, the longer you wait between cleanings, the system will have less airflow to work with. After 60 days, the system will work too hard to be effective, and your energy bill can increase.
- Electrostatic washable filter
- Lifetime warranty
- Cleaned with water in less than 5 minutes
- Needs constant cleaning to remain efficient
- Can cause airflow blockages
6 Types of Furnace Filters
As I mentioned earlier, there are multiple types of air filters. As promised, let’s take a more in-depth look at the various types of furnace filters and how they work.
Disposable fiberglass filters are the most common filters for residential applications. They use a glass fiber that gets tighter and tighter woven the deeper into it you go. The tightness of the woven fibers increases the MERV and MPR ratings.
Most HEPA rated filters can restrict airflow because they are woven so tight. There isn’t enough surface area to be efficient. However, they are cheaper than most other options and come in more sizes. You can get them in 10 inches up to 60 inches, usually 1 or 2 inches thick.
Pleated allergen filters use a paper fiber filter material and are pleated to increase the surface area. The more pleats in the filter, the more surface area there is for air to flow through and to catch particles. The pleats allow for more filter material and tighter filtering to capture airborne particles down to 3 microns in size.
These anti-allergen styles come in all residential sizes ranging from 12 inches to 60 inches and aren’t much more expensive than the fiberglass models.
Electronic Air Cleaners
Electric air cleaners are separate units and not part of your home’s HVAC system. These stand-alone devices filter the air that passes through them, collecting large particles like dust in filters of their own. They also use electronically charged plates that attract the ions in viruses and bacteria, preventing them from escaping the air purifier.
Activated carbon filters, or charcoal filters, are anti-allergen, and the pleats or paper fibers are coated with bits of carbon. The carbon captures pollutants and odors to help minimize smells in your home.
With the charcoal or carbon on the filter material, airflow isn’t restricted, and along with in-home allergens, they also capture cigarette smoke and some coughing and sneezing particles. You can get these in all sizes for your home or office HVAC systems.
HEPA Furnace Filter
HEPA filters come in all types listed above. These filters are fiberglass, paper, or mesh material and are rated to capture particles down to 3 microns, including mold, mildew, pet dander, and pollen.
Most sizes are available for residential and commercial needs, though the larger sizes, depending on build material, can get a little pricey compared to some other options.
Washable filters have a cloth material that will stand up to rinsing and light scrubbing (by hand). Each filter has a life span of at least a year, though they need to be washed frequently.
These are usually flat filters, though some pleated versions exist. They are more expensive than the rest because of their longer lifespan. As they get washed and reused, though, they become less effective. It isn’t uncommon to have to replace them before the recommended time is up because they have broken down too much to continue being useful.
How to Measure Your Old Furnace Filter
If you move into a home and there isn’t a filter or the filter that is there doesn’t have the measurements listed on it, you will have to measure yourself. The best method is to use a tape measure. However, you should know your measurements will differ from those listed on the filters.
The measurement you take is called the exact measurement. Your dimensions will be in fractions instead of whole numbers. This is the actual measurement of the filter or space and needs to be converted to the nominal measurement.
Nominal measurements are whole numbers, rounded up. For example, if your exact measurement is 11 ¾ inches, the nominal measurement will be 12 inches. This is important to note because different brands will have the same nominal measurement but could have different exact measurements.
Nominal measurements will be sufficient enough for most applications. If, however, you find the fit to be too loose or too tight, you may need to find the listings on the packages for the exact measurements to get a better fit.
How to Change a Furnace Filter
Changing your air filter is a quick and straightforward process that doesn’t require any tools. The first step is to locate your air register that houses the filter. Some units will have this in the ceiling or in the wall. Other units will have the filter in the air handler housing itself.
There will be thumb slides or set-screws holding the register grate in, and when removed, it will open. These grates are generally hinged on one side, so they don’t fall off entirely. Make sure the HVAC system is off and open the grate.
Remove the old filter and dispose of properly. Before you remove the filter all the way, look for the arrow showing airflow direction. If the filter is absent, airflow is always from the register towards the air handler (arrow points into the wall or ceiling).
Place the new filter in the filter slot following the airflow arrow. Close the register grate and secure with the set-screw or thumb slides and return the HVAC system to service.
If you would like a more detailed explanation, you can watch this video to see how it is done.
Frequently Asked Questions
Do higher MERV filters restrict airflow?
It is possible for higher MERV rated filters to restrict airflow. The pleated filters will capture a lot of smaller particles but will increase the static pressure in the air handler, making it work harder with less airflow. For your residential system, a MERV 8, 11, or 13 rating is considered high but efficient. Anything higher, though, and you risk restricting the airflow.
What is the best MERV rating for furnace filters?
The best MERV rating will depend on what it is you are trying to filter and the size of your HVAC system. A residential system will perform well and filter most in-home allergens with a MERV 8 to 11 filter. This will balance cost and performance.
How often should I change furnace filters?
Furnace filters should be changed regularly. Most filters are rated to last between 30 and 90 days. Some thicker (4-inch filters, for example) can last 6 to 12 months. This depends on what you are filtering. If you live in an area with a lot of dust, sand, or other airborne contaminants, you need to change the filter more often.
Is a furnace filter the same as an air filter?
Air filters, furnace filters, HVAC filters, air handler filters, heater filters, or whole home filters. They are all names for the same thing. Your heater, air conditioner or central heating and air combination unit all use the same filter, no matter what you call it.
What happens if you put a furnace filter in backwards?
The filter will restrict airflow when installed backward. With charcoal or carbon activated filters, the charcoal can become dislodged and contaminate the air handler. Always make sure you install the filter with the airflow arrow indicator facing in towards the air handler.
Is it advisable to wash and clean non-reusable furnace filters?
While washable and reusable filters can be cleaned and will hold up well after several wash cycles, it is not advisable to wash or clean disposable furnace filters. They will fall apart and won’t work properly if they get wet.
Choosing a filter for your HVAC system is harder than installing one. Once you have a brand picked out, you still need to choose between types, MERV ratings, price, and longevity.
While most people find a brand and style they like and stick with it, don’t be afraid to try different filters to find which ones work best with your system and provide the pure air your home deserves. If you are in doubt where to start, I suggest you go with the top pick, the Filtrete MPR 1000. It is HEPA rated, pleated, and sized for most residential applications.
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