Find Compatible Filters for the Following Brands
- AAF Air Filters
- 3M Filtrete Air Filters
- Abatement Technologies
- Accumulair Air Filters
- Ace Air Filters
- Trion Air Bear® Compatible Air Filters
- Air Demon Air Filters
- Air Guard Air Filters
- AIRx Air Filters
- Replacements for AllergyZone Air Filters
- Amana Air Filters
- AmericanAirFilter Air Filters
- American Standard Air Filters
- Aprilaire Air Filters
- Arm & Hammer Air Filters
- BestAirPro Air Filters
- Broan/NuTone Air Filters
- Bryant Air Filters
- Carrier Air Filters
- ClimateMaster Air Filters
- Coleman Air Filters
- Dynamic Air Cleaner Refills
- DuPont Air Filters
- Electro-Air Air Filters
- Endust Air Filters
- Field Controls Filters
- Five Seasons Air Filters
- Febreze Air Filters
- Flanders Air Filters
- GeneralAire Air Filters
- Glasfloss Compatible Air Filters
- Goodman Air Filters
- Indigo Air Filters
- Honeywell Filters
- Honeywell Air Filters
- NordicPure Air Filters
- Lennox Air Filters
- Lysol Air Filters
- Payne Air Filters
- Nordyne Air Filters
- Permatron Air Filters
- PrecisionAire Air Filters
- Pro1 IAQ Air Filters
- PuraFilter 2000 Air Filters
- Purolator Air Filters
- ReservePro Air Filters
- Rheem Air Filters
- Ruud Air Filters
- Skuttle Media Filters
- SafeHome Air Filters
- Space-Gard Air Filters
- TopTech Air Filters
- Totaline Air Filters
- True Blue Air Filters
- WaterFurnace Air Filters
- Trane Air Filters
- Ultravation Air Filters
- White Rodgers Air Filters
- York Air Filters
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21x21.5x1 Air Filters
WHY YOU SHOULD REPLACE YOUR AIR FILTER
Reduce your energy costs with clean filters
A dirty filter in your furnace or AC system will raise your energy bills. A dirty filter restricts the air flow into your system's air handler, causing it to work harder to cool or heat your home.
Improve airflow & efficiency of your furnace
A dirty clogged filter can restrict furnace or AC airflow and potentially cause problems with the system. They also cease to filter allergens and other particulates out of your air.
Increase the longevity of your furnace or AC system
Dirty, unchanged filters can make your furnace or AC system fail completely. Repairing a broken system can end up costing you a pretty penny.
WHAT DO MERV RATINGS MEAN?
Allergies, pets, odors and smoking all can greatly affect the quality of your indoor air. Discount Filters offers many different types of discount air filters to help you breathe better air inside your home based on your specific needs.
We carry discount air filters in 1-2 inch standard sizes, and 3-5 inch media sizes. Our air filters are great and work well in HVAC systems, furnace and air conditioner systems. If you are looking for a custom size air filter you can request that we make a special size for you. As always, we offer Fast Shipping & Free Returns on all of our discount furnace filters.
- MERV 8: The most basic air filter a homeowner will need is a MERV 8. A MERV 8 filter offers excellent air filtration for their home. A MERV 8 air filter would be good for a family that doesn't smoke, doesn't have pets, and doesn't have bad allergies.
- MERV 11: People with pets and/or light allergies, would greatly benefit from a more advanced filtration level called a MERV 11. A MERV 11 filter reduces pet dander, dust, pollen and other particles that are present in your home.
- MERV 13: A MERV 13 air filter however will capture even smaller dust particles, dirt, pollen, mold spores, pet dander and more from your home's air. A MERV 13 air filter is great for people with regular allergies and who own multiple pets. The MERV 13 filter is typically more expensive and will also put more strain on your HVAC system, however the high quality filtration you will get will be well worth it.
Frequently Asked Questions
I'm looking for a 21x21.5x1 filter for my furnace - will an air conditioning filter work?
Depending on where you live, you might refer to the filter one way or the other. The good news is - it doesn't really matter. All forced air heating/cooling systems use a filter - which serves to keep your equipment clean and to promote good indoor air quality in your home.
How often should I change my furnace / air conditioner filters?
It's important to change your 21x21.5x1 air filter to keep your heating and/or cooling system operating at peak efficiency. There are general guidelines for filter change intervals: Replace 1" fiberglass/polyester filters every 30 days. Replace 1" and 2" pleated filters every 90 days. Replace 4"-5" filters every 6 months.
What is a HVAC filter?
HVAC stands for Heating Ventilation and Air Conditioning. "HVAC system" refers to the system that regulates (heats/cools) and moves air throughout your home. In addition to keeping your HVAC system clean, your filter removes airborne particles and allergens from the air in your home.
How do I choose my whole house air filters?
The industry standard for rating the efficiency of air filters is "MERV", which stands for Minimum Efficiency Reporting Value. Manufacturers and retailers have attempted to simplify things by creating different comparison systems. Examples: FPR (Filter Performance Rating), or MPR (Micro Particle Rating), or even a good/better/best/ultimate system. At DiscountFilters.com - we organize our filters into different categories - "Dust", "Allergy", "Health" and "Odor". We provide information on the common contaminants that each filter category removes on our product pages.
How do I know what air filter to purchase?
The first things to consider when looking for an air filter are dimensions. Most air filters will have dimensions printed on the side of the filter frame. The "nominal size" is the size you see printed on the filter; it originates from the actual size, which is rounded up to the nearest whole inch.
What 21x21.5x1 air filters do you recommend for my furnace and/or air conditioning system?
We carry a huge selection of filters in many different sizes. We stock many more sizes than the local "big box" or hardware store. In most of the common sizes - we might have 5 different choices ranging in price and efficiency. We recommend the AIRx "Allergy" filters (MERV 11) as these offer the best combination of performance and value.
What is a MERV Rating?
MERV stands for minimum efficiency reporting value. MERV ratings are an air filter industry standard. The higher the MERV rating, the more particles are captured as well as the ability to filter smaller and smaller particles. While higher MERV ratings are better at filtering, air flow is reduced slightly. Residential furnace filters range from MERV 8 to 13.
How do I install my 21x21.5x1 air filter?
Be sure to turn off the power to your furnace before changing your air filters. Remove the old air filter and discard it. When placing your new air filter into the grille, make sure the arrow on the side of the filter is pointing towards the furnace. Turn your furnace back on.
What is the difference between nominal and actual size?
Air filters are typically measured in inches. A popular filter size is 16" x 25" x 1". This is the nominal measurement, as all of the lengths are rounded up to the nearest inch. These size filters, if you measured them exactly, are 15 ½" x 24 ½" x ¾". This is to ensure that the air filter you order fits snugly, but doesn't need to be shoved into position. It's better to have a filter that's slightly smaller than one that's too big for its compartment.
What is a HEPA filter?
HEPA (high-efficiency particulate arrestance) furnace filters are in a premium-quality class of filtration. To meet HEPA standards a filter typically must remove at least 99.97% of particles that have a size of 0.3 um. HEPA filters are usually used for commercial, industrial, and healthcare applications. However, a HEPA filter can be used for people who suffer from allergies and respiratory issues.
What kind of debris will a new air filter capture?
All air filters will attempt to capture a variety of different household pollutants such as dust, dust mites, lint, and pollen. A MERV 13 air filter will capture those particles plus very fine dust and even bacteria. If you have pets in your home a lot of what is captured in your filter will be pet hair and dander.
How do washable filters work?
Washable air filters, also referred to reusable air filters, are a great alternative to disposable filters if you're looking to change to an eco-friendly filter. Reusable air filters offer excellent filtration that's comparable to that of disposable filters. In addition, they are great if you have sufficient back yard space to clean them and are willing to take the time to clean them.
How do I choose the correct air filter?
The best way to ensure you get the correct size air filter is to look at your existing air filter. Most current air filters will have the size on the air filter or it will have a part number. If your existing air filter doesn't have the dimensions listed on the side, you can measure it yourself. Measure your air filter for length, width and depth. These dimensions are called actual dimensions. Then you'll need to round each actual dimension up to the nearest inch to get your nominal dimensions which you can then find by searching on our air filter finder.
How can air filters save me money?
Air filters can save you energy costs and maintenance fees. Buy replacing your air filters, you can improve the lifespan of your system. If dust and dirt build up on the filter it can cause the system to have to work harder in order to heat and cool your household/workplace. This can increase your energy costs and increase the likelihood of providing upkeep on your system
Why should I change my air filter?
Changing your air filter not only helps save money, but it helps increase the quality of your indoor air which keeps your lungs healthy. Air filters trap particles in the air and if particles build up, the air in your home or workplace can become dirty. This can cause sneezing, coughing, wheezing and more to start to occur. By changing your air filter regularly you can provide a healthier environment for you and your family.
What's a furnace filter?
A furnace filter helps remove airborne particles (allergens, dust, etc.). These airborne particles can cause damage to your heating and cooling system, which can decrease the efficiency of your unit. Not only do furnace filters help improve energy and efficiency of your furnace, these filters also help improve of the quality of your indoor air too.
Why do you need to change your air filter?
All air filters should be replaced every 3-6 months. The reasoning for changing air filters is to help improve your indoor air quality. Many air pollutants can be found in your home, such as radon, dust, smoke, chlorine, asbestos and more. By changing your discount air filter you can reduce the likelihood of these particles existing within your indoor air, allowing you to breathe cleaner and possibly helping reduce illnesses.
How to clean reusable air filters?
To clean your reusable air filters, follow these easy steps: Find your air filter and remove it. Use a brush or a vacuum to remove the debris that has built up on the air filter. Place the filter in a tub, bucket or sink filled with water and a little bit of vinegar. Let the filter sit in the water for about an hour. Once the hour is done, let the filter dry. (Place a towel under the air filter or let it dry in direct sunlight.) Place the filter back into your unit.
Which way does my air filter go?
Our filters are made and packaged to provide the correct instructions on the direction that your air filter should go in. Typically there will be an arrow on the side of the filter which will indicate which way to insert the filter.
What are washable air filters and how do I use them?
Washable air filters are different from your average air filter. These filters are made out of woven polypropylene media and heavy-duty steel, which can be used for heat pumps, sensitive furnaces and any systems with limited air flow. Washable air filters are also eco-friendly and cost effective for homeowners due to their material. Most air filters need to be changed every 3-6 months, where washable air filters can last up to 5 years or a lifetime (if maintained and washed properly). Make sure to wash your filter every 3-6 months for optimal performance.
How do I measure my air filter?
Measuring your air filter is easier than you think. One of the best ways to find the size of your air filter, is to check the outside of the filter to find the part number and size. The other way to find the size of your filter is to measure it yourself. The measurements of the air filter go by length, width and depth. It's also important to know that the length and width are interchangeable. For example, if your filter is 14 X 20 X 1, it can also be 20 X 14 X 1. Be sure to measure your air filter to the nearest whole number in order to find your correct size.