Air Filter vs. Air Purifier: Is Your HVAC Filter Enough?

Written By Lester Mclaughlin
Updated On

Are you wondering if your HVAC filter is enough and how air filters and air purifiers differ?

You’ve come to the right place!

In this Blue National HVAC guide, you’ll learn:

  • All about air filters and air purifiers
  • Their differences
  • When air filters aren’t enough

And much more!

Air Filter Vs. Air Purifier

So, if you’re looking for answers on the ins and outs of air filters and air purifiers, keep reading our detailed guide below to get answers to all of your questions!

How Does An Air Filter Work?

A residential air filter works using mesh materials that trap tiny particles as air blows through it. This type of filter is also known as a media filter. 

Typically, air filters are installed near the indoor unit of your furnace, air conditioner, or heat pump. All of the air supplied flows through the filter before being pumped into the rooms of your home via the ductwork. 


Over time, the filter traps enough dust, dirt, and other particulates that it will inhibit the airflow. This is why filters should be checked routinely and replaced or cleaned when they are dirty. 

Besides media filters, electronic filters provide a more sophisticated filtering performance. Like media filters, electronic filters use an electronic charge to attract and capture particulates. 

What Are The Benefits Of HVAC Filters?

The primary function of air filters is to keep the inside of your HVAC unit, so it can continue to operate efficiently. It does this by capturing most airborne particulate and air pollutants, including:

  • Dust 
  • Dander
  • Pollen
  • Pet hair
  • Pet dander
  • Tobacco smoke
  • Dust mites
  • Mold and mildew
  • VOCS (volatile organic compounds)
  • Cooking smoke
  • Germs, bacteria, viruses, and other pathogens

Most HVAC filters do their job quite well, but not all are created equal. Air filters with higher MERV (minimum efficiency reporting value) ratings filter out smaller particulates (below 2.5 microns) than those with lower ratings.

Keeps Your House Clean

Since the air filter is capturing dust, dirt, and other airborne particles, that means they are not being distributed throughout your home. Just think about it– if you did not have an air filter, every time your HVAC system turned on, you’d have dust billowing out of your duct. 

In actuality, the dust likely wouldn’t be visible to the naked eye, but you’d undoubtedly have to dust your furniture every day to keep your home clean. 

Maintains the HVAC System’s Efficiency

Air filters ensure your HVAC system does not get clogged with dust and dirt. Furnaces, air conditioning units, and heat pumps work best when they are clean and uninhibited from a buildup of dirt and dust. 

For example, a furnace can transfer heat better when the burner and heat exchanger is clean. Additionally, a blower will use less energy to move the air if the fan blades aren’t weighed down with a layer of dust. 

To summarize, air filters help your HVAC stay efficient, which in turn lowers the electricity or gas it uses to heat and cool your home. Therefore, with a properly maintained air filter, you can reduce your monthly energy bills. 

Makes the Air Cleaner

If you’ve gotten this far into this guide, you likely know that air filters remove dust and other particulates from the air, making it cleaner. But what does that mean to the occupants of the home?

When the air is filtered, dust, particulates, and even viruses and bacteria are removed from the air. As such, the occupants in the home are no longer breathing in these things. They will have less respiratory effects and overall less frequency of illness due to the cleaner air. 

Why Isn’t Your HVAC Filter Enough?

Sometimes air filters alone are not enough to filter the air in your home. Perhaps you live in an area with high outdoor air pollution, have lots of pets, your cooking produces a lot of smoke, or your home just produces a lot of dust and indoor air pollution.

Whatever the case may be, your HVAC filter might not be able to keep up. Here are common reasons why future air purification is needed.

HVAC System Isn’t Compatible with High MERV Ratings

Most HVAC systems (furnaces, central air conditioners, and air-source heat pumps) work with air filters with a MERV 13 rating with no issues. However, if you use a filter with a MERV rating higher than 13, you can create equipment issues if the filter replacement goes too long.

It is often difficult to determine what MERV rating your HVAC system will work with, as filter recommendations are not commonly labeled on the unit. If you have any doubts on what type of filter is compatible with your HVAC system, give our team of HVAC experts a call for assistance. 

In the case that your HVAC system does not work with a high MERV rating and you want to improve your air quality, you have no recourse in using a better filter. However, you can use an air purifier to help (which we will get to later). 

HVAC System’s Filter Track Is Too Narrow

The hole size for the HVAC filter in your AC unit or furnace might limit you on the size and rating of filter you can use. If you notice the air quality in your home is poor and you want to add additional filtering, you might consider an air filter with a higher MERV rating. 


However, air filters with a higher MERV rating tend to be thicker, upwards of 5 inches wide. If your HVAC system can only fit a 2-inch filter, then you won’t be able to increase your air filtration. 

No Central HVAC System 

Perhaps your home does not have a central HVAC system. It might not have ductwork at all, and you cool and heat select rooms with mini-split heat pumps, window AC units, portable air conditioners, or space heaters.


In this case, all of these smaller-sized HVAC systems feature few filtering capabilities. Sure, you can pull out the filter of your mini-split unit or window air conditioner and clean it, but they are generally tiny and don’t capture as many particulates as a MERV 13 filter would (for example). 

If you have one of these heating and cooling systems, you may have to treat the air in your home with an air purifier. 

How Do Air Purifiers Work?

An air purifier is an air cleaning device which is generally a stand-alone device that sits on the floor. It sucks the air in on one side and blows it out on the other. While the air travels through the air purifier, it passes through dense filters and sometimes ultraviolet (UV) lights, killing most bacteria, viruses, and other pathogens. They can also remove excess humidity (moisture) from the air. 

Air purifiers remove more particulates than standard HVAC air filters, even those with the highest MERV ratings. While standalone air purifiers are more common, you can get a whole-house air purifier that connects to the ductwork of your HVAC system. 

How Air Purifiers and Air Filters Differ

Air filters are rectangular devices with built-in mesh materials that capture particulates as the air gets pushed through them. They go inside of your existing HVAC system and should be checked monthly for cleanliness. 


On the other hand, air purifiers are generally standalone devices that suck air in, filter and clean it, then blow clean air out. You can think of them as a “supplemental filter” that does much more than a regular HVAC filter. Air purifiers have denser filters, can treat the air with UV lights, and sometimes even dehumidify. Air filters capture larger particles, while air purifiers capture smaller ones and larger ones too. 

Often, air purifiers use HEPA filters, which are denser than MERV filters and capture more and smaller particulates. True HEPA filters are often too dense to be used in central HVAC systems as they inhibit too much airflow. 

What Are The Advantages of Air Purifiers?

Air purifiers provide many advantages to homeowners. They reduce the spread of viruses, bacteria, and germs and make your home feel more comfortable. If you or other home occupants have respiratory issues and allergies, a home air purifier may help. Here are their top advantages. 

Kills Germs, Bacteria, Mold, and Viruses

Sometimes air filters alone are not enough to stop the spread of viruses, bacteria, mold spores, germs, and other harmful pathogens. While your standard HVAC filter might trap these dirty buggers, they could dislodge and make their way to your respiratory tract as the air passes through. 

On the flip side, air purifiers can trap these pathogens in their built-in filters and kill them with UV light, electrostatic precipitator technology, an activated carbon filter, or ions (with an ozone generator or ionizer). 

Less Respiratory Issues 

Since air purifiers provide a higher degree of air filtration and destroy pathogens, the air you breathe in is cleaner. This means if you’re susceptible to allergies, asthma, or just, in general, get sick often, you will now be less likely to have respiratory issues. 

Cleaner Home

Remember how HVAC filters help keep your home clean by filtering out the dust and other particulates? Well, air purifiers do the same thing, but on steroids. Even better, if you have a standalone air purifier and an air filter in your HVAC system, your home’s air cleanliness will be almost twice as good. So clean, your vacuum cleaner might start collecting dust. 

How To Select The Best Air Filters And Purifiers For Your Home?

Selecting the best air filters and air purifiers for your home might be a daunting task, especially if you don’t know where to start. Consider the following factors and give our team of HVAC pros a call today if you need further assistance. 

HVAC System’s Filter Requirements 

Depending on your HVAC system, you might not have the capability to install the air filter you desire. For example, your furnace might have a filter space that is too narrow for a high MERV-rated filter. Or your HVAC system might not have a blower that is rated high enough to push air through a MERV filter with a high rating. In that case, the filter or the HVAC unit might fail. 

Geographic Location and Outdoor Air Pollution 

If you’re living off the grid in the wilderness of Nebraska, you would have very different filter requirements than if you were living near downtown Las Angeles. If you live in an area with high levels of outdoor air pollution (like LA), you should use more robust filters and air purifiers in your home. 

The air circulated into your home comes from the outdoors, so the outside air quality and pollutants should be considered when determining which air filter and purifiers are right for you. 

Occupant’s Sensitivity 

Some people can take a faceful of smoke from a camping fire and not even blink, while others break into a sneezing fit by just looking at pictures of pollen. Suppose you or other occupants in your home have sensitive allergies or a respiratory system weakened by a health condition. In that case, you should consider getting the highest rated MERV filter your HVAC system can accept.

Additionally, you should use high-efficiency particulate air purifiers to cleanse the air further, remove allergens and contaminants, and prevent any adverse respiratory effects from flaring up. 

Pets, Smoking, and Cooking

Pets, smoking, and cooking are not just random words pulled out of a hat; they are factors you should weigh in selecting HVAC filters and purifiers for your home. 

Most pets shed, leaving their fur and dander to float around through the air. Smoking indoors should be avoided, but if it is done indoors, extra filtering and purification will be necessary to mitigate secondhand smoke. 

Lastly, cooking not only puts food on your family’s plates but also adds smoke and particulates to the air as well. Always turn on the cooking vent when you’re whipping up a meal. However, vents don’t capture 100% of the cooking smoke, which, if you cook often, will significantly impact the indoor air quality of your home.

If your indoor air quality is negatively affected by your cooking, use the best air purifiers with high clean air delivery rates to counteract the smoke.

Meet Your HVAC Expert

Lester Mclaughlin

HVAC systems are highly technical and often is the most misunderstood part of the house. From ductwork to heat pumps, I've been exposed to all sorts of issues facing homeowners. It really irks me when a homeowner is given bad advice like refilling freon vs fixing a leak in the system. I'm here to help our website readers with their heating and a/c problems.
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