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Lennox X6673 OEM 20x25x5 MERV 11 HCF20-11 HCF20-16 Replacement Filter

This Genuine OEM Lennox replacement filter (X6673) is the same as HCF20-10, HCF20-11 and fits model number Air Cleaner Cabinet HCC20-28. This MERV 11 filter has a nominal size of 20 x 25 x 5 and an actual size of 19 3/4 x 24 3/4 x 4 3/8.This filter is up to twenty times more effective than ordinary fiberglass filters. High efficiency filter media collects small dust particles before they can collect on your coils. No assembly combs needed...filter just slides right in! This product is listed and rated by Underwriters Laboratories as U.L. Class 2.

  • Nominal size 20" x 25" x 5"
  • Actual size 19 3/4" x 24 3/4" x 4 3/8"
  • Model X6673
  • 98% efficient filtration media
  • Recommended Replacement Every 3 Months
  • Up to twenty times more effective than ordinary fiberglass filters No assembly required

Customer Reviews

Based on 14 reviews
I will be buying again.

I received excellent customer service. I will recommend this place to my friends and family, and I do not ever recommend places to others.


Exactly what I ordered. Fast shipping and great price. Thank you.


Great product as always. Fast shipping. Thanks so much.

Perfect fit and fast delivery and at a great price

Perfect fit and fast delivery and at a great price. This is my first Lennox X6673 OEM 20x25x5 MERV 11 HCF20-11 HCF20-16 Replacement Filter from the Atomic Filters store as an online purchase. In the past I've used a BestAir 20" x 25" x 5" Pleated Replacement Air Filter MERV 13 Carbon filter @ a price of $68.00 from Menards although unfortunately they only last about 3 months before the air flow is diminished to a point where alerts are set or your AC freezes up. That said they do a great job at catching everything but just not worth the price. Although I would prefer a higher MERV count, it's not worth the price (my opinion). The OEM MERV 11 does a great job and at this price I can change them more often and not feel the pain. Buying them in bulk also helps that effort.

I will report back after my second purchase and this up and coming winter where these will be put to the test again.

Furnace Filters

I have not used the filters yet so I cannot give a review? The filters did arrive in a timely fashion. I will be usubg them in the future, however.

Related Items

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 is 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 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 and that it also has the foam to ensure a snug 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.

Find Your Filter Sizes Easy in 1" Deep Filters , 2" Deep Filters, 4" Deep Filters