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How to Choose the Right Home Air Filter Every Time

by Kevin King September 09, 2017

How to Choose the Right Home Air Filter Every Time

 Have You Ever Had Trouble Finding the Right Replacement Furnace Filter?

Nobody loves changing out air filters, but it’s something that has to be done if you want to keep your home healthy and HVAC system happy. The problem is that most homeowners aren’t quite sure how to choose the right filter for their furnace. Do you?


Do You Replace Your Filters Enough?


Do you replace your home’s furnace filters enough? Knowing when to change out dirty filters and replace them with clean ones plays an important role in (1) keeping your family safe and healthy and (2) allowing your HVAC system to run at optimal efficiency. Unfortunately, there isn’t a standard answer. When you should replace your filters depends on a number of factors.

 how often should you Replace your furnaces filters

One of the first things to consider is the useful life suggested by the furnace filter manufacturer. Most filters clearly recommend how often they need to be replaced – typically ranging from one to six months. At the time of installation, use a marker to write the date. This allows you to come back a few months later and calculate how much life you have remaining on the filters.

 Home Air Filter Change Date

When checking the date, it’s also smart to conduct a physical exam of the filter. Does it look extremely dirty, or does it still appear to be in good condition? If you suffer from allergies and/or have pets in the house, you’ll likely need to replace your filter before the manufacturer’s recommended date.

 Save money on utilities by changing your filters regularly

Replacing an air filter is a pretty simple and straightforward process. It’s the cost that causes most people to put off this important home maintenance task. However, consider that the U.S. Department of Energy claims replacing a dirty filter with a clean one can lower HVAC energy consumption by 5 to 10 percent – resulting in significant monthly savings. It also causes your system to work less, which extends its life and prevents costly repair issues down the road.


4 Things to Consider When Choosing a New Filter

 Air Filter Sizes

Now that you’re aware of the need for changing air filters in your home, let’s move on to the biggest challenge homeowners often have: sorting through the variety of filters available on the market and finding the right one for the right price. Here are a few things you’ll want to consider:


  1. Nominal vs. Actual Size


The very first thing you have to figure out is what size furnace filter you need. Typically this is as simple as looking at your current filter and – assuming it fits appropriately – finding the dimensions on the label. There is, however, some confusion when it comes to size – so let’s touch on that.

 Finding the right Furnace Filter every time - Filter sizing by Atomic

Your filter technically has two sizes. The first is the “actual size,” which is the true dimension of the filter. For example, your filter might come out to 19.5x19.5x0.75 inches with a tape measure. However, to simplify the buying process, filter manufacturers round these numbers up to create a “nominal size.” Using the previous example, you would actually need a 20x20x1 size filter.


  1. Efficiency Ratings


Once you know what size you need, the second most important thing to consider is the filter’s efficiency. Thankfully, The American Society of Heating Refrigeration and Air Conditioning Engineers (ASHRAE) have developed a standard rating system that the air filter industry follows. Known as MERV, this numbering system allows consumers to compare different brands and filter types against each other and determine how effective different products are in removing airborne particles.

Nominal Filter Sizing vs Actual Filter Sizing MERV Ratings by Atomic


MERV ratings range from 1 to 16, with the higher numbers correlating to smaller filter pores for better filtration of airborne particles. While you may assume that higher ratings are automatically better, this isn’t necessarily true. The smaller the filter pores are, the more resistance to airflow there is. This puts pressure on your system and can ultimately make it inefficient.

MERV ratings explainded Filter Efficiency


The key is to find the highest MERV rated filter that still allows your system to operate at maximum airflow. Most homeowners will find that their systems work best with MERV ratings between 8 and 13.


  1. Air Filter Designs


Not all air filters are designed the same. The different features found on various products are intended to provide unique benefits. The biggest difference you’ll notice is pleated vs. non-pleated.

 Choosing the right filter Pleated vs non pleated furnace filters

In general, pleated furnace filters are deemed more efficient and durable. They feature more surface area, which theoretically allows them to catch more contaminants and particles while still allowing for maximum airflow.  Flat-panel fiberglass filters usually aren’t recommended, unless you’re only worried about cost and very basic protection.

Pleated HVAC Filters


  1. Washable vs. Replaceable


The final decision you have to make is whether you want to go with the standard replaceable filters we’ve discussed in this article, or if you’re interested in paying a little more for a washable filter.


Washable filters – as the name suggests – simply need to be rinsed with a garden hose on a monthly basis, air dried, and then put back in place. They’re intended to last for many years and prevent the need for regularly purchasing filters every few months.


The biggest problem with washable filters is that they typically only have a MERV rating of 1 to 4. In other words, they catch the big particles, but aren’t very effective at trapping bacteria, viruses, pet dander, and allergens.


Choosing what kind of filter you want comes down to a simple list of pros and cons. Replaceable filters are more airflow restrictive and require you to buy new filters regularly, but they tend to catch more airborne particles. Washable filters are less restrictive, which means they let more particles into your home, but only need to be replaced every few years.


Make Changing Your Air Filters Easy


Once you find the right filter, your goal should be to make it as easy as possible to replace the filter without forgetting. At Atomic Filters, we make the process of replacing your filters simple, easy, and affordable. Simply subscribe to the filter that fits your needs and we’ll deliver a new one when it needs replacing!

Choose Your Brand: 

Lennox Furn Atomic Filters  Trion Air Bear Furnace FIltersCarrier Air Filters  Aprilaire Furnace Filters  Honeywell Furnace Filters

Kevin King
Kevin King


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Nominal Vs. Actual Sizes: Finding the Right Air Filter Size

Buying the Correct Size Air Filter- The Most Important Thing to Know 

When you are buying your air filter online most important thing to know is Air Filters have two sizes that you need to understand the Nominal size and the Actual Size. Not understanding these numbers often leads to consumers purchasing a filter that does not fit their Furnace or HVAC system.

Nominal vs Actual air filter size by Atomic


Understanding Nominal Filters Size Could Save You Time and Money

Not understanding the Nominal Filter Size is the primary culprit for incorrectly purchased filters.The Nominal Size are the usually the dimensions used to Label the filter. For instance 16x20x1. These dimensions are a rounded value on the filters actual measurements. The actual measurements on this filter may be 15.5x19.5x.75, but that could vary by brand and manufacturer. So in order to make sure you have the correct size filter, especially if you are replacing with a different brand it is important to confirm the actual size on the filter. When purchasing filters on the internet the Nominal size is usually found the in the product title.

Actual Filter Size- The Key to Making the Right Replacement Filter Purchase

The actual size as you might have guessed are the actual dimensions of the filter by length, width and thickness. This size is often on the filter right below the Nominal size and is usually labeled as the actual size. When you are buying a filter online the actual size is sometime in the product bullet point or the product description. If your filter does not have actual dimensions on the outside of the filter, you can measure you filter to get the correct dimensions. Some brands have a foam gasket on the outside of the filter, in this case you will want to make sure you have a compatible actual size size and that it also has the foam to insure a snag fit. 

Lennox Air Filter X0851 with Foam strips

Examples of Nominal and Actual Sizes

 Size  Example 1  Example 2
Nominal Size 20x20x1 16x20x1
Actual Size 19.5x19.5x.75 15.75x19.75x.75


 Furnace filters should fit securely but should not have to be forced into position. If you have to force the filter into its slot, then it is probably too big. Forcing an improper filter size in a filter can cause it to buckle, damaging the filter or reducing its ability to function properly. Filters are a smaller than their slot to allow for easy replacement. Some HVAC units may need a filter with dimensions that are unique or uncommon. In these cases, a custom filter needs to be ordered.