Best Air Conditioner Filters Guide: How to Choose the Best AC Filter for Your Home?
The role of an AC filter within an HVAC system is crucial. Unfortunately, they are often overlooked and are given only a secondary thought. Most of the time, when you are getting your air conditioner tuned up by an HVAC professional, you may hear the term ‘air conditioner filter’, especially if it is a dirty one.
Seemingly unassuming and looking nothing more than a piece of cardboard or stiff cloth, AC filters are often the first and last line of defense for your indoor environment against harmful particulates and foreign matter. Here is a brief overview of what AC filters are, their functions, types, and most importantly, we answer: How to choose, maintain, and change an AC filter.
You can always monitor your AC’s filter status using smart AC controllers. This helps you keep your air conditioner unit in top condition.
What are AC filters?
As with any filter, air conditioner filters consist of a porous structure, through which coarse and big harmful particles cannot pass through. These filters do not let dangerous pollutants and allergens enter your indoor environment through the air conditioning. For this reason, they have a marked effect on your health and well-being.
AC filters are often made out of a fine fiberglass thread which is then spun on a frame, or from fine paper or cloth which is wrapped on a cardboard frame. Some of the particles which an air conditioner filter can help protect you against are:
- Outside air pollutants
- Animal hair
- Dead skin
These are especially important for people who are sensitive to air quality, have allergies or diseases such as asthma. Overall, they can benefit us all by resulting in an improved air quality, considering you make sure you don’t have a dirty AC filter.
AC Filter Efficiency Ratings
Efficiency is a word that is often thrown around very loosely, but we are often unaware of what it means, and how it is measured. For AC filters, this is measured through “Minimum Efficiency Rating Values”, or MERV for short.
The MERV goes from 1 to 16. The number is dependent on the amount of matter of a particular particle size in which the filter can stop. The following figures are given by the United States Environmental Protection Agency.
|MERV||Average Particle Size Efficiency in Microns|
|1-4||3.0 – 10.0 less than 20%|
|6||3.0 – 10.0 49.9%|
|8||3.0 – 10.0 84.9%|
|10||1.0 – 3.0 50% – 64.9%, 3.0 – 10.0 85% or greater|
|12||1.0 – 3.0 80% – 89.9%, 3.0 – 10.0 90% or greater|
|14||0.3 – 1.0 75% – 84%, 1.0 – 3.0 90% or greater|
|16||0.3 – 1.0 75% or greater|
Source: US EPA
As can be seen from the table, a higher value means more stopping power. But be careful! Having a higher MERV does not mean you should get a 16 MERV filter for your home. Each filter has its application setting.
MERV filters from 1 to 4 are the standard common filters and provide a basic level of filtration at a low cost. Filters with a MERV of 6 to 8 are commonly used in residential settings. They employ the pleated cloth type of filters.
Mid-range are from MERV of 9-12 and are of relatively high quality. They are capable of filtering out particles of 1 micron or greater. Filters with a MERV of 13-16 are used in industrial and laboratory settings where a very clean atmosphere is essential. Particles of 0.3 microns and greater are captured with the help of these filters. Naturally then, these filters also cost much more than the lower MERV filters.
High MERV filters are very effective, but also very dense, thus potentially interfering with the airflow, especially if the air to be filtered is excessively dirty. This can lead to a reduction in the cooling and heating power of your HVAC system and have more of a negative effect than a positive one.
Types of AC Filters
With the introduction of new technologies, air conditioner filters are also improving in their modes of operation and forms. The following are some of the most commonly used AC filters:
Fiberglass filters: Perhaps the most common type of all, these filters are designed for single use only. Strands or fibers of fiberglass are spread out over a metal or cardboard frame. This fiberglass then serves as a barrier for harmful particles.
This type of filter is on the lower end of the spectrum as far as MERV ratings go, but due to its low cost, it’s a popular option among homeowners.
High-Efficiency Particulate Arrestance (HEPA) filters: These are the talk of the town these days. HEPA filters work at a very minute scale and are strictly controlled by regulations. This type of filter can filter 99.97 percent of all airborne particles sized 0.3 microns or larger according to the American standard of a ‘True HEPA’ filter.
The working mechanism of a HEPA filter is slightly different from other types to ensure the effective elimination of particles. While this is a bit of a technical discussion, the glass fibers in a HEPA filter form a fibrous maze and are captured either by colliding with a fiber or through sieving, interception, or diffusion.
Thanks to a high MERV of 17-20, HEPA filters are capable of trapping bacteria and tobacco particles from the air. But their high cost and the need for a professional contractor to install them makes them only suitable for people with specific needs such as allergies and illnesses.
Pleated filters: Very much similar to fiberglass filters, pleated filters use polyester or some other cloth material to perform the filtration. They are usually much more capable of stopping dust flow into a room.
The polyester cloth is arranged in an accordion shape, giving them a much larger surface area than flat filters. The larger surface area presents less of a resistance to airflow and makes for longer-lasting filters.
Reusable/Washable filters: Washable AC filters are cloth-based filters that can be washed and then used again. These are fairly cheap filters that are designed for low-intensity use. This is because they usually have a MERV rating of 1-4, which doesn’t make them suitable for high pollutant environments.
Care also has to be taken while washing them so that they do not get damaged. They need to be completely dried before being put back into use, or else mold and fungi can grow in them.
Why do you Need to Change Your AC Filters?
By now we know that AC filters trap harmful particles and pollutants from the air and allow clean and fresh air to travel into a room. Over time, these particles can accumulate within the filters and reduce the total volume of air passing through them. Less air passing through the filters means that you would have to turn your AC’s fan settings up a notch to achieve the same effect, and in some cases, even that might not work.
The result is a higher energy bill at the end of the month and degraded AC efficiency. Both things which we do not want! Clogged AC filters can result in energy bills to rise to 15% higher than normal.
Another drawback of a clogged AC filter is the reintroduction of harmful particles into the air. Due to the large number of pollutants captured in the filter, when an AC reverses its airflow, there is a high chance that some of these pollutants will make their way back into the air and result in even dirtier air than before.
This is why it is imperative to regularly change or clean your AC filters. But, how often to change an AC filter? The recommended time is 3-4 months, and always before the start of a busy summer season. Make use of a smart AC controller to monitor the status of your AC filter and clean it before it’s full!
Maintenance Tips – DIY Changing & Cleaning AC Filters
Buying a new air conditioner filter isn’t the end-all and be all. You need to keep a track of the cleaning cycle, and also need to maintain it from time to time.
Dirty AC filters are a major cause of air conditioners not heating or cooling properly. Be sure to check the filters out first thing if this is the case with your AC, and have the AC filter changed.
A clogged-up air conditioner filter can increase the load on your AC’s fans, and cause them to work at a high setting all the time.
A dirty AC filter that is already fully blocked cannot trap any more dirt and dust and is an active source of contaminants within the HVAC system (especially for ducted systems). As discussed before, dirty AC filters cause the AC to work at a higher power setting. This can lead to higher power usage and higher energy bills.
This is why it is imperative to have the AC filter cleaning done regularly, and possibly an AC filter change as well. A visual inspection is usually enough for the purpose. You can hold the filter up against a light source, and if you can see through it, then it’s good to go. Otherwise, a replacement or cleaning is in order.
We are often asked, how to change the AC filter? This is an easy one to answer. AC filters for ducted systems are placed in the outdoor units or furnace units and can be easily taken out by the homeowner by just unclipping and pulling them out of their holders. For ductless systems, the filters are placed within the indoor unit, and again can be easily taken out by a slight pull.
Wondering how to clean an AC filter? Cleaning is usually as easy as a gentle blow over with an air hose, or a workover with a vacuum cleaner. Washable air conditioner filters can be washed under running water, but be careful to completely dry them before putting them back in.
Things to Keep in Mind with AC Filters
Pleated Filters Give Higher Efficiency
The pleated structure of such filters, resembling an accordion, gives the most surface area for the filter in contact with the air. This enables more filtration capacity than a simple flat structure. This has a couple of effects on your HVAC system.
A higher amount of airflow can be achieved through such a filter since there is more space for the air to pass through. Moreover, such filters can last longer than flat filters, because they can hold a larger amount of dust and particles before needing to be changed.
Smart AC filters
Smart ACs and smart AC controllers are becoming rapidly popular these days. One innovative feature which smart controllers bring to the table is of monitoring your “Air Filter Status”. With this feature, users can track when their filter needs to be replaced. When you have a dirty AC filter, a notification pops up on your mobile phone alerting you that an AC filter change is due. This can save the user from breathing in stuffy air and having a clogged filter for days on end.
Know When to Use HEPA Filters
HEPA filters are not always the solution. If you are living in a rural setting with clean air and no pets, a HEPA filter might not be what you need, and a normal filter can do the job.
Air Conditioner Filter Sizes
When buying a new air conditioner filter, you have to be careful in selecting the right one for your HVAC system. Different models are designed for different sizes, and no one size fits all. AC filter sizes are usually expressed as Length x Width, but the depth of an AC filter also needs to be taken into account. Common depths range from 1 to 6 inches. Some common AC filter sizes are:
- 10 X 20
- 14 X 20
- 16 X 24
- 18 X 30
- 12 X 12
- 14 X 24
- 16 X 25
- 20 X 20
- 12 X 20
There are many more sizes available other than these as well. You can also get a customized AC filter made. To know the size of the AC filter which your AC accepts, simply look at the dimensions printed on your old AC filter, or have a look at the owner’s manual of your AC.
Enjoy the Clean Air!
Now you know all there is about AC filters, their types, applications, and also tips for keeping them in top shape!
The importance of a clean environment cannot be understated, as this greatly affects your health and productivity. Be sure to check out the most suitable air conditioner filter for your application, and enjoy the benefits of clean air!