18x20x4 Air Filters for Furnace & AC

If you want your HVAC system to continue running smoothly, then it’s important to maintain your system on a regular basis. Your system consumes a big part of your energy bill. A dirty filter can make your system work harder. When you notice low airflow, consider checking your air filter – it can get so dirty that it will become difficult for air to pass through the filter.

Depending on what type of filter your HVAC system requires, Merv Filters LLC provides a wide range of air filters, available in standard and custom sizes. We ensure that your system’s air filter remains clean so that your family breathes healthy air and your home stays comfortable.

Product Specifications

  • Nominal Size: 18x20x4
  • Made in: USA
  • Actual Size: 17 1/2 x 19 1/2 x 3 3/4
  • Price: $79.60 – $136.20
  • Available in: 4, 6 Packs
  • Designed to last: 90 days
  • Pleats made of: Synthetic media
  • Frame made of: Beverage board
  • Delivery Time: Within 3-5 business days from the order date

Benefits of the Merv Filters LLC 18x20x4 Filter


18x20x4 air filter (like the ones made by Merv Filters LLC) comes with a lifespan of 90 days, which is more than standard fiberglass filter.

Made In The USA

All of our 18x20x4 air filters are “Made in the USA”.

Ultra High Quality

The quality of 18x20x4 furnace filter depends upon the Minimum Efficiency Reporting Value (MERV) rating, which is developed by the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE). The higher the value, finer the filtration. The top-performing filter is Merv 13, which can help you remove most particles from your air.


Ideal for basic and standard residential and commercial use.

MERV 11:

Ideal for standard and superior residential and commercial use.

MERV 13:

Ideal for superior residential and commercial use and smoking lounges.

Note: Color of the 18x20x4 AC Filter may slightly differ from the image shown here due to photographic effects or your screen settings.

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