Is Your Air Filter Too Efficient? (HVAC Air Flow Problems)

April 7, 2020

So, your HVAC system is usually pretty “go with the flow,” but right now, your problem is low air flow! This is a common problem and can have more than one cause. That’s what we’re going to go over today, so you can “get your flow back”!

First of all, we want to address the possibility that maybe your air flow isn’t too low, but it just seems like it when you put your hand over the vent. Since we don’t expect anyone who’s not a trained HVAC professional to be able to tell the difference between low air flow vs. a different issue causing the temperature in a room to be un-ideal, we recommend that you call us if you’re not sure.

Without further ado, here’s what causes low air flow, according to doctor and HVAC analyst Dr. Allison Bailes:

When air moving through a duct hits snags on uneven parts of the inside surface of the duct, the air slows down. The degree to which this happens depends on what material the duct is, how dirty it is, and whether there are little gaps or holes.

Another thing that could be causing the air to slow down due to friction:

A dirty filter, or actually, a filter that is TOO efficient. (Just humor us for a moment here!)

Your filter becomes thicker when it’s dirty, which restricts air flow. That means it will be unevenly distributed throughout your home. Everything from dust mites, to pollen, to bacteria, to pet dander can clog up your filter.

So that’s a dirty filter, but what do we mean by a filter that is TOO efficient?

Basically, if you have a great filter (high MERV rating), then the openings/pores in the filter are smaller. Smaller openings naturally mean less air flow. So, does that mean that you should purposely get a worse filter in order to improve air flow? Absolutely not!

The only way that having an efficient filter would impede air flow is if your system’s motor isn’t strong enough for the filter. If you feel like your system isn’t blowing the air out hard enough and there isn’t enough air flow, then you should check to make sure that the motor is rated to handle your MERV filter.

(Also, there are different kinds of high-MERV filters. A thicker filter – four or five inches – lets more air pass through since it’s larger. It can also catch more dust.)

If you aren’t quite sure, you can always give us contact us. We are the best company for all your HVAC needs, because not only do we care about your air flow, but we also care about your cash flow!