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Lennox 21x26x4 MERV 16 Upgrade Kit X8344

Lennox 21x26x4 MERV 16 Upgrade Kit X8344

The Lennox X8344 MERV 16 Filter Upgrade Kit is an upgrade kit for the Lennox PCO-20C Healthy Climate Air Purification System. This Lennox filter kit includes one MERV 16 filter, also known by part number X6669, and six UV bulbs, also known by part number X8149. The pleated air filter features a MERV 16 rating, which allows it to trap very small airborne particles and prevent them from circulating in your home.

The UV light bulbs utilize UVA light rays in order to oxidize contaminants in the air without using toxic chemicals. Be sure to replace these UV bulbs once per year in order to achieve the best possible results with your air cleaner.

Lennox X8344 MERV 16 Filter Upgrade Kit specifications:

  • Does not include insert
  • Replace filter every 6-12 months
  • Fits the Lennox PCO-20 air cleaners
  • Includes one MERV 16 filter and six UV bulbs
  • Approximate filter dimensions: 21x26x4

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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.

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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. 

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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