What Size NovusAer Filtration System Do I Need?
- Dan Dearden
- Aug 26, 2025
- 3 min read
Updated: Sep 2, 2025
Response by Dan Dearden, CAFS – Certified Air Filtration Specialist, Essential Air Products Founder, NovusAer Inventor
Great question! The simple answer is this: go with the biggest NovusAer that will fit in your system.
Why? Because with NovusAer, bigger is always better. A larger filter size means better airflow. Better airflow means your heating and cooling system works more efficiently, lasts longer, and delivers cleaner air to your home. And since all NovusAer sizes cost the same, there’s no financial reason to “go smaller.”
That said, there is such a thing as going too small—so here are some easy guidelines:
Step 1: Match Your Air Conditioner’s Capacity
Air conditioners are measured in “tons” of cooling, and each ton requires about 400 cubic feet per minute (cfm) of airflow.
Example: A 3-ton unit needs about 1,200 cfm → choose the NovusAer NS12 model.
A 3.5-ton unit needs about 1,400 cfm → choose the NovusAer NS14 model.And so on.
Step 2: If You Can Fit Bigger, Do It
If your space allows a larger NovusAer than the “normal” match, go for it. More airflow means even better performance and efficiency.
Step 3: If You Can’t Fit the Normal Size
Sometimes space is tight. If you have to go down a size, it may still work—but your contractor should check your duct pressures and airflow to make sure the smaller filter won’t create too much resistance.
Following these steps works in about 98% of installations.
Why NovusAer Works Better in Real Life
Here’s what a decade of field testing has shown:
Most homes don’t actually get “normal” airflow. Poor duct design and duct installation practices mean most systems only deliver 300–350 cfm per ton instead of the ideal 400. This means that:
Filters in real homes behave differently than they do in labs
If like in the example above you put in a NovusAer NS12 for a 3 ton, 1,200 cfm system, the air flow resistance would be even better (lower) than it is rated.
If you needed an NS14 for your 3.5 ton, 1,400 cfm system, but you only have room for an NS12, it will likely work because your system is likely only flowing at about 1,225 cfm.
Lab tests aren’t the same as home reality. In labs, air flows evenly (called “balanced laminar flow”) across the filter. See diagram A below:
In real homes, airflow is uneven and turbulent, which can make ordinary filters 3–6 times more restrictive than their ratings suggest. Those products are not tested in homes under real operating conditions. Take a look at diagram B below:
NovusAer was designed for the real world. We tested NovusAer filters for years in customer homes before ever sending them to an ASHRAE-approved lab. The results? Contractors report that the airflow resistance they see in their own installations matches exactly what our published tables show.
After four years of real-life, in-home testing, the NovusAer filter was finally put through the official process at an ASHRAE-approved laboratory. (Illustrated below.)
What makes NovusAer different from other filters is that it wasn’t designed just to look good in a lab test. From the very beginning, it was built and tested in actual customer homes—where airflow is messy, ducts aren’t perfect, and conditions are far from “ideal.”
And the results speak for themselves. One contractor even installed a NovusAer in his own home system and later sent us a photo. His report? The airflow resistance he measured in his house matched exactly what we publish in our performance tables. In other words, what we promise on paper is what you actually get in your home.
A Word About 1” Filters
If your system currently uses a 1” filter, here’s the hard truth: it’s probably hurting your efficiency.
Independent tests show that 1” filters can account for up to 44% of HVAC performance and efficiency loss—no matter what MERV, FPR, or MPR rating they claim.
Swap one out for a NovusAer, even if it’s technically “undersized,” and you’ll almost always improve your system’s efficiency and performance.
Bottom Line
Choose the largest NovusAer that fits your system. You’ll breathe cleaner air, protect your HVAC investment, and likely lower your energy bills—all without paying more for a larger size.
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