7 Little-Known Facts About HVAC Air Filters

7 Little-Known Facts About HVAC Air Filters

One of the most common HVAC problems is poor maintenance or failure to change HVAC air filters. A dirty air filter means that dust, dirt, and other particles are building up in your central AC system.

Most of us understand the importance of changing your HVAC air filters. As consumers, we have options. How much do you really know about filters? Read on for seven things you may not know about AC air filters.

1. The Purpose of HVAC Air Filters is Not About Air Quality

The purpose of HVAC air filters isn’t to improve air quality in your home. They protect the system’s HVAC equipment from harmful particles and debris.

Many filters are marketed to homeowners as being keys to eliminating allergens and improving air quality. While they do that, those features don’t really go hand-in-hand with protecting the AC unit.

2. The Higher the MERV Rating, the Lower the Efficiency

What is the MERV rating? The Minimum Efficiency Reporting Value (MERV) measures how effectively an air filter blocks particles and other debris from entering an HVAC system.

The higher the MERV rating, the smaller particles it can filter. Thus, the higher the rating, the better the filter. Most of the time.

MERV ratings go from 1 to 20. A MERV rating of 1 only removes the biggest dust particles. MERV 20 the highest grade. You usually find it only in medical settings where the air needs to be extremely clean.

Though, hospitals and other medical facilities have high-power, commercial-grade heating, and air conditioning systems. Those systems can accommodate those high-efficiency filters.

Most residential central AC systems can’t handle a MERV 20 filter. The system would need to work too hard to push the air through the filter.

Typically, a residential system can take as high as MERV 13 without straining too much. Anything higher than that begins to cause problems.

Highest Rated Filters Can Restrict Airflow

Not all air conditioning filters are made for all air conditioners. Most residential systems are not designed for the highest-rated air conditioner filters. Your HVAC system may not have the motor or fan capacity to accommodate higher efficiency filters.

In fact, some home AC systems are designed for filters with a MERV rating no higher than 4. The result is restricted airflow throughout your home.

High-Efficiency Filters Can Damage Your Unit

As stated above, high-efficiency air conditioning filters can actually slow airflow in furnaces and air conditioners alike. They can reduce your unit’s efficiency. This, in turn, raises your electric bill and can cause damage to your unit over time.

Your furnace may overheat. Likewise, the filter can cause your air conditioner’s condensing coils to freeze. Homeowners have long been told that dirty HVAC air filters can cause this. They certainly can, but so can the wrong filter.

It’s wise to understand your air conditioner’s requirements when it comes to choosing your air conditioner filter.

3. Filters Do Less for Air Quality than You Think

HVAC air filters do not reduce the number of small particle in the air that you think they do. Particles tend to be present wherever there is human activity.

That’s not always where your ductwork and registers are to capture them. Most of your home’s air is filtered through a single point in your HVAC system.

In addition, a furnace or central AC unit only runs seasonally. The unit can’t filter air when it is not running. And, an efficient unit won’t run twenty-four hours per day.

You’d have to run the fan all year long and on a continuous setting to keep your air filtering. An air filter is a critical component of your HVAC system. Though, it does allow your central heating and air to double as an air purification system.

4. Unadvertised Drawbacks to a Washable Air Filter

Many homeowners invest in a washable air filter with the intent of saving money. Washable filters can last up to five years. You would go through 60 or more disposable filters in that amount of time.

Rather than replacing the filter every month or so with a new one, you simply remove and wash the same filter. Let it dry, and then reinsert.

While a washable filter is more expensive, you are only buying one. This makes them more economical in the long run. Though, there are some drawbacks to having a washable air filter.

Washable Filters Have a Low MERV Rating

A washable air filter usually rates only a 1 to 4 on the MERV scale. That isn’t effective if your intent is to purify the air or reduce allergens.

If you’re looking to filter out smaller particle like smoke, aerosol sprays, and pet dander, the washable air filter may not be effective compared to a disposable filter with a higher MERV rating.

Damp Filters Can Attract Mold

A washable air filter can attract mold. After you wash the filter, it takes a long time to dry. If you reinstall one while it’s still damp, you’re inviting mold.

Mold and mildew require a warm, moist environment in order to survive. So, mold spores are right at home in a damp filter. The mold easily spreads through your HVAC system.

The moving air will carry mold spores throughout your ductwork and into your home. Ironically, the air filter that was designed to remove pollutants from your home becomes the source for them.

5. Electrostatic Filters Aren’t Equivalent to HEPA Filters

You may have heard a lot of talk about the efficiency of reusable, electrostatic filters. There’s a lot that happens as air moves through these complex filters compared to simpler filters. Here is what you may not know.

How Electrostatic Filters Work

As your HVAC system draws air into the return vents and ductwork, the air passes through the air filter. The filter removes particles and dust from the air before the HVAC system conditions the air.

Electrostatic air filters have layers and layers of filtration that clean the air as it passes through the filter. As particles pass through the filter, the filter material positively charges them.

Then the particles attach to the next set of layers of the electrostatic filter. The particles begin to bind together. They become too big to pass through the filter and into the AC system.

How Electrostatic Filters Stack Up Against HEPA Filters

The Environmental Protection Agency (EPA) and Occupational Safety and Health Administration (OSHA) state that HEPA filters are the best for removing indoor air pollutants.

HEPA filters filter air at a very fine level. They block elements as small as 0.3 microns or larger. HEPA filters catch 99.97 percent of all particles. If you have a health need for a high-quality filter, a HEPA filter is still your best bet.

6. What Happens When You Don’t Change Your Filter

If you don’t change your air conditioner filter often enough, you will spend more money on your utility bill without seeing any benefit.

A dirty filter means slow moving air. This increases the run time of your central AC system. More run-time usually means cooler air. Though, the temperature will not vary as it should if the air filter is clogging the system.

You Risk Clogging Your System with Debris

When your filters are clogged, particles escape through the filter and get into the mechanical and electrical components of the AC system. The longer you go without changing the AC filter, the greater the buildup.

This increases the potential for damage to your unit. The faster you can heat or cool your home, the less you have to run the HVAC system. Thus, the longer you unit will last.

Your Home Heats and Cools Unevenly

If your system does not have adequate airflow, your system cannot effectively move the air to the furthest rooms of your house. As the air filter clogs, less and less air moves through.

As a result, the rooms further away are too warm in the summer and too cold in the winter. The air in those rooms can even become stagnant.

The rooms closest to the unit will be more comfortable because they are receiving the most airflow.

7. Save by Ordering in Bulk

Most of us buy our filters from home improvement stores like The Home Depot. Air conditioning filters are packaged individually or in small quantities. This and the marketing and labeling that comes with them drives up the price.

Try buying your filters in bulk and having them shipped to you. Doing so cuts out some of these retail and advertising costs. Online companies like ours offer quality filters at better prices than do some of your local retail stores.

Review Your HVAC Air Filters

Now that you’ve made it this far, it’s time to take a look at your HVAC air filters. Do they have the proper MERV rating for your system? Do you feel you are getting proper filtration? Is the temperature the same in every room?

If the answer to any of these questions is no, you may have the wrong air filter in your HVAC system. If you’re looking for the right filter, our selection of AIRx filters will have the perfect one for you and your home!

5 thoughts on “7 Little-Known Facts About HVAC Air Filters”

  1. I have a Trane electronic filter for my AC unit . I would like to improve the dust control efficiency of it by using a pre-filter (one of your merv 11) at the entry of the single return to the AC. Does this sound like this will work for me or a recommendation ?

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