Can Dirty Filter Cause Furnace Not Work
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Changing your furnace's air filter every three months can keep it performing at top levels while contributing to better indoor air quality and reducing energy costs. An excellent way to remember this essential activity is to replace your filter in conjunction with the change in seasons. Regular maintenance ensures the filter won't become clogged with dust, pet hair, and other airborne particles, which can reduce the furnace's efficiency. There are a wide variety of filters available, and some do a much better job of trapping certain particles than others.
Keep reading to learn everything you need to know about choosing the best furnace filter for your system and to find out why we've chosen the following replacement filters as some of the top choices for most homeowners.
- BEST OVERALL: Nordic Pure MERV 12 Pleated AC Furnace Air Filters
- BEST SMART FILTER: Filtrete Smart AC Furnace Air Filter
- BEST BANG FOR THE BUCK: FilterBuy MERV 8 Pleated AC Furnace Air Filter
- BEST FOR ALLERGIES: AIRx ALLERGY MERV 11 Pleated Air Filter
- BEST FOR PETS: Aerostar Allergen & Pet Dander Pleated Air Filter
- BEST FOR MOLD: Filter King MERV 8 Pleated AC Furnace Filters
- BEST FOR NEUTRALIZING ODORS: Flanders NaturalAire Air Filter
Types of Furnace Filters
As far as home improvement gear goes, furnace filters may rank among some of the least exciting products. There's none of the danger and raw efficacy of power tools, none of the visual impact of perfectly mitered crown molding, and certainly none of the reassurance that accompanies significant investments like new windows or new roofing.
But furnace filters have the power to carry a big impact with a small footprint, and finding the right furnace filter can save money, improve air quality, and help prevent future HVAC repairs. Originally, filters were designed to protect the moving parts of the furnace itself. Thanks to technological advancements, filters now also prevent harmful particles from cycling back into the air that you breathe at home. Furnace filters are rated by their minimum efficiency reporting value, or "MERV." The higher the rating, the more efficient the filter is at trapping airborne particles. The numerical range is from 1 (lowest efficiency) to 20 (highest efficiency). Read more about MERV ratings below.
Disposable Fiberglass
The disposable fiberglass filter is the option that comes to mind when you think "furnace filter." Created from 1-inch-thick spun fiberglass, it does little more than prevent larger particles like dust, lint, and debris from gunking up your system. MERV rating: 2-3, cost: $1 to $2
- Pros: Very inexpensive and good for renters and those without allergies or asthma.
- Cons: Has little to no effect on cleaning the air.
Disposable Pleated
Disposable pleated filters, a popular option made from polyester or cotton paper, can remove some small particles like spores and mites, but need to be changed frequently to avoid clogging and taxing your HVAC system. MERV rating: 6, cost: $4 to $5
- Pros: Relatively inexpensive, can be made from green materials, and blocks some small particles.
- Cons: Can add more resistance to airflow, making your system more expensive to operate.
High-Efficiency Pleated
The granddaddy of furnace filters is high-efficiency pleated options made from deep 4- to 5-inch thick pleated synthetic cotton attached to a very rigid metal grid to prevent leaks or fluttering. MERV rating: 14-16, cost: $100
- Pros: Used in hospitals, they screen out the smallest of particles. May be beneficial for those with respiratory problems or autoimmune disorders.
- Cons: At $100 a year annually, this is an expensive option and can only be installed in special housing due to its thickness.
Disposable Electrostatic
A disposable electrostatic filter contains self-charging electrostatic cotton or paper fibers that attract and trap small particles. MERV rating: 10.
- Pros: Affordable in standard sizes and is a good solution for homes with children, pets, or smokers.
- Cons: Custom sizes are expensive, leading to higher costs if replaced regularly over several years.
Reusable Electrostatic
Similar to their disposable counterpart, a reusable electrostatic filter contains self-charging cotton fibers that attract particles. Permanent options have a removable, machine-washable filter you can reuse for six to eight years. MERV rating: 8.
- Pros: Little waste, more effective than pleated, and a good option if you use a standard size.
- Cons: Less effective than electrostatic, and custom sizes are expensive.
Polyester
This reusable filter is denser than fiberglass, so it blocks more airborne particulates, and it comes in either a flat or pleated version in thicknesses up to four inches. MERV rating: 8.
- Pros: Traps up to 91 percent of common airborne particles, including pollen and dust.
- Cons: Does not eliminate the need to clean HVAC coil at least every few years because some of the particles will still slip through.
HEPA
A high-efficiency particulate air (HEPA) filter blocks up to 99.7 percent of airborne particles that are 0.3 microns and larger, but it isn't readily available in sizes to meet standard furnaces. Because HEPA filters are so dense, they can reduce airflow into the furnace, so like high-efficiency pleated filters, they're typically used only in commercial furnaces or hospital settings. MERV rating: 16-20.
- Pros: Blocks the highest level of airborne particulates.
- Cons: Not suitable for most residential furnaces.
Photo: amazon.com
What to Consider When Buying a Furnace Filter
Choosing the best furnace filter requires matching the filter to the furnace manufacturer's specifications. Just because one filter blocks more particles than another doesn't mean it's the right choice for your furnace.
Filter Size & Thickness
Furnace filters come in dozens of sizes, with 16-by-20-inch, 20-by-25-inch, and 16-by-25-inch being the three most common sizes. Filter thickness varies from one to five inches, and in general, the thicker the filter, the more particle-blocking ability it will have. Before choosing a filter, you'll need to check the owner's or operating manual, because not all furnaces will accept a thicker product. As the filter gets thicker, the furnace must work harder to pull air through it, reducing its efficiency and useful life.
Washable vs. Disposable
Changing your furnace's filter regularly (every three months is ideal) will help keep dust and other particles from damaging the furnace's working parts, such as its heating coils and fan. Disposable filters are lightweight, relatively inexpensive, and can be tossed out after using. Washable filters feature a heavier aluminum frame with electrostatic fibers that serve as the filter. A washable filter, depending on the brand, may last a few years. Still, it requires a specific washing procedure, which may include separating the filter into layers and washing them separately. You must also make sure a washable filter is completely dry before reinstalling it to prevent mold and mildew growth. For many, using disposable filters is the quickest and most straightforward solution.
MERV Rating
Furnace filters are assigned a minimum efficiency reporting value (MERV) based on their density. While denser filters trap more airborne particles, they should also be changed more frequently because they tend to clog more quickly. The MERV scale runs from 1 to 20, and filters in the 6 to 12 range are designed for residential use. Your furnace's operating manual will recommend the MERV rating that's best suited to your unit. Higher efficiency filters are mainly used in commercial settings and health facilities where the HVAC units are powerful enough to draw air through a dense filter easily.
Climate
Where you live can factor into the type of furnace filter that's best for your home. In humid rainy areas, mold growth is a common concern, so if you live in a damp region, you'll want to choose a furnace filter with a MERV rating of at least 6 in order to block mold spores from being drawn into the furnace and then recirculating inside your home.
Our Top Picks
The best furnace filter should protect the working parts of your furnace and trap dust, pet dander, and pollen to keep these airborne pollutants from recirculating in your home.
Photo: amazon.com
Changing furnace filters is a snap with Nordic Pure MERV 12 Pleated AC Furnace Filters, which block a high level of dust and other airborne pollutants that could otherwise end up in the furnace or recirculating throughout your home. These disposable pleated filters are hypoallergenic and feature electrostatic fibers that attract pollutants, and they resist mold and mildew growth. They'll also keep unwanted pet dander, pollen, dust, and lint from circulating in the air. The filters are 1 inch thick and come in a variety of sizes and filter ratings. The MERV-12 rating is a high filter rating that collects the most common air pollutants. In typical home or office environments, these filters can be replaced every three months.
Photo: amazon.com
Available in dozens of sizes and with Bluetooth technology to monitor your filter use, the Filtrete Smart AC Furnace Air Filter is a top choice for a furnace replacement filter. With a proprietary algorithm that detects airflow to track usage of your filter, users can worry less about changing the filter at the right time. The high-efficiency MERV-12 rating makes it an excellent choice for homeowners who want to trap as much airborne debris as possible. Filtrete uses exclusive 3-in-1 technology to trap lint, dust, pet dander, soot, pollen, and mold spores. The 1-inch thick filter is narrow enough to fit in most wall registers or many slide-in filter holders. Download the Filtrete app to monitor and receive alerts about the filter status.
Photo: amazon.com
It doesn't require a lot of money to get a quality furnace filter. With a FilterBuy MERV 8 Furnace Filter, you can choose from a variety of filter sizes and thicknesses ranging from 1 to 4 inches, making FilterBuy a great value. Each filter frame is made of beverage board, which is designed to withstand humidity and temperatures up to 200 degrees Fahrenheit. The filter will trap up to 90 percent of airborne particles, including lint, pet dander, and pollen to keep your furnace running clean for up to three months before it needs replacing.
Photo: amazon.com
The disposable, pleated, AIRx ALLERGY MERV 11 Pleated Air Filter is designed with extra density to trap airborne allergens that can trigger allergy symptoms including smoke, pollen, dust, and pet dander. It comes in a variety of sizes that are 1 inch thick to fit in most furnaces and has size filters in each pack to make it easy to replace them when needed. The MERV 11 filter has a high pleat count that helps prevent allergens from recirculating through your home's ductwork. For the best clean air results, use this filter in conjunction with other allergen-reducing measures, such as a vacuum with a HEPA filter and an air purifier to keep airborne allergens at bay.
Photo: amazon.com
If you have pets, check out the disposable, pleated, Aerostar Allergen & Pet Dander MERV 11 Air Filter that blocks a high number of airborne particles, including pet fur and pet dander. This high-efficiency, electrostatic filter attracts particles and traps them in place without creating a low airflow resistance. It is available in a range of sizes and thicknesses from one to four inches, making it an excellent choice for a variety of furnaces and return-air vent compartments. It's recommended to change this filter every two to three months in the fall and spring, and monthly during heavy furnace use, such as in winter.
Photo: amazon.com
If you live in a humid region, consider Filter King MERV 8 HVAC Pleated AC Furnace Filters. These are designed to trap many pollutants, including mold spores, while still allowing free airflow so as to reduce the risk of mold or mildew growth. Filter King's disposable pleated filters are available in a variety of 1- and 2-inch-thick sizes to fit a wide range of furnaces and come in a pack of four. The manufacturer recommends replacement once every three months at a minimum.
Photo: amazon.com
Whether your home has a wood-burning fireplace or the chef of the family tends to scorch meals regularly, the Flanders NaturalAire Odor Eliminator Air Filter will help neutralize that smell of smoke and other lingering odors. The 1-inch thick, disposable pleated filter absorbs smells and eliminates unwanted odors while trapping other airborne particles, such as dust and pollen. Each filter is made with baking soda which is the key factor in reducing the odors circulating in the home or office. The filter comes in a variety of sizes and should be changed a minimum of once every three months.
FAQs About Your New Furnace Filter
With a variety of furnace filters on the market that all promise to do a great job of trapping airborne particles, it's only natural to have some questions about the best furnace filter for your home.
Q. What is the best MERV rating for furnace filters?
While MERV ratings go all the way up to 20, the highest-rated filters are generally reserved for health and research facilities. For residential furnaces, a rating of 12 is a great option.
Q. Is a thicker furnace filter better than a thinner one?
Not always. Thicker filters are denser and block more dust and particles, but they may also cause the furnace to work harder to draw in air. Use only the type and thickness of the filter recommended by the furnace's manufacturer.
Q. What is the best type of furnace filter for viruses?
According to a CNN article, HEPA filters with MERV ratings of 17 to 20 are best for reducing the spread of viruses, but most household furnaces cannot draw air through a dense HEPA filter.
Can Dirty Filter Cause Furnace Not Work
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