How to choose the best residential air filter

How important are air filters in your home HVAC system? Should you buy a mechanical or electrostatic filter? Do you need a HEPA filter? Choosing the best air filter for your home requires that you think about your particular needs. Filters can protect against cardiovascular diseases, improve respiratory conditions, and help you live a healthier life. In this article we will discuss what kind of air filter is best for less frequent filter replacement, protecting your HVAC equipment, and protecting your health.

Residential air filters are medium-efficiency filters, typically with a MERV 8 or 9 rating and a depth of one to five inches at most. They must have a low-pressure drop since residential unit fans cannot handle too much airflow restriction.

A shield with an air filter glows at the top left of the image. The filter is green and the background is forest green. In the centre of the page are a house and an apartment building

How do air filters work in a house or condominium and how do they function best?

Air filters in residential HVAC systems work similarly to commercial or industrial air filters. They clean the air coming in from outside or being recirculated in the home. However, they usually see less contamination than commercial units. 

If there are pets in your home or high particle generating activities like cooking, filters will need to be changed more frequently. 

Residential systems have lower air changes per hour compared to commercial or industrial units, meaning they don’t receive as much air going through the filter. They can get rid of larger contaminants—3 to 10 Microns— efficiently, but are not very efficient at removing smaller particles such as PM1 or PM2.5. Because residential units do not run 24/7, the filter only captures particles when the unit is on.

Due to the mid-range efficiency of most residential air filters, their main function is to protect HVAC coils and other components as opposed to properly protecting people. The fan in residential units can’t handle high efficiency filters unless it is upgraded. MERV 13 pleated filters have been available for many years; however, these filters decrease in efficiency throughout their life. In order to maintain a MERV-13 efficiency, these filters need to be changed out more frequently before they begin to degrade. 

Air filters in residential units keep contaminants out of the ducting. Duct cleaning isn’t required on a regular basis unless there is major construction or there are a lot of renovations happening in the home.

Why are air filters important for good health? 

If you want to protect your health from harmful particles, it is recommended to use a filter with a MERV-13 rating (read more on how MERV ratings are determined) or higher. Filters with a rating below MERV-13 are generally used to protect equipment. However, 1-inch, 2-inch, and 4-inch filters in MERV-13 are electrostatically enhanced, and they tend to lose their charge over time. Therefore, to maintain MERV-13 efficiency, it is advisable to replace the filter before it starts losing its charge. It is difficult to determine the right time to change the filter. As a general rule, it is recommended to change these MERV-13 charged filters every two to three months, in a residential system.

If you require extra help due to allergies or any other conditions, a portable air cleaner may be necessary. To determine the size of the air cleaner, calculate the cubic footage of the room by multiplying its length, width, and height, then dividing the result by 60, and then multiplying it by 8 to get the required CFM for an air cleaner. Portable air cleaners are designed for individual areas, so place them in rooms where you spend the most time, to keep those areas clean. You can also purchase an air cleaner on wheels and can move it from room to room depending on your needs. If you have severe allergies or serious health complications, you may consider upgrading your HVAC system with a high-efficiency filter, MERV-13, MERV-14, or MERV-15, and upgrading the fan. Leaving the fan running will ensure optimum performance. Upgrading may require significant initial retrofitting costs, but at the same time the air filter in this system can last up to 3-5 years and you can save on filter replacement costs for the lifetime of the new system.

What are the different types of residential air filters available in Canada?

In Canada, there are various types of residential air filters available for different needs. Panel filters with fiberglass pads, other synthetic media pads, or synthetic media wrapped around a wire support, are filters commonly used in apartment units and are low-cost, low efficiency filters. They are designed to capture large particles but are not so effective at trapping smaller particles such as allergens.

Pleated air filters, MERV-8 at minimum, are recommended. Having a higher MERV efficiency in capturing smaller particles will enhance indoor air quality.

Electrostatic air filters are also available. They use static electricity to attract airborne particles.Electrostatic air filters must be regularly cleaned and maintained to remain effective. They also lose efficiency as soon as the electrostatic charge dissipates.

What are the differences between a panel filter for HVAC, an air purifier, and an air cleaner?

A panel filter is installed into the HVAC system itself, whereas an air purifier, usually featuring a HEPA filter, is a portable unit totally independent of the HVAC system. Air cleaners are either portable units or large units used in commercial or industrial applications.

What is the difference between an electrostatic air filter and a mechanical air filter? 

There are many benefits to using a mechanical air filter. Unlike an electrostatic filter, a mechanical filter maintains its efficiency throughout its life, which means that once you buy a filter with a certain efficiency level, it will keep that level until you replace it. However, one potential downside of a mechanical filter is that it has a slightly higher initial pressure drop compared to an electrostatic filter, which could reduce airflow depending on the capacity of your fan. To address this, if your HVAC system can’t handle a MERV-14 or MERV-15 filter, it’s best to stick with a MERV-13 filter.

While electrostatic filters can provide high efficiency particle capture, they tend to lose their charge and efficiency over time, which means that they need to be replaced more frequently. In residential units, only mechanical filters up to MERV-9 can be used in a 1-inch or 2-inch track. If you want a higher efficiency filter, you can go up to a MERV-13, but it will be electrostatically charged and won’t keep its efficiency as long as a mechanical filter. Additionally, you can incorporate UV filtration or activated-carbon filtration for more protection.

What does a multi-stage air filter do?

Multi-stage air filters, include stages of prefilters, activated carbon filters, and HEPA filters. They may also include a UV chamber that helps to eliminate viruses. They capture larger particles, allergens, and odours, as well as submicron particles. They improve indoor air quality by trapping contaminants and removing them from the air stream. Residential systems do not usually incorporate multi-stage filtration unless they are custom designed.

What factors should be considered when choosing the best residential HVAC air filter? 

If you want to keep your home clean and with minimal dust particles, then you should use a MERV-8 or MERV-9 mechanical pleated filter with at least 15 or 16 pleats per foot. This will also give you a longer filter life. However, if you have allergies or other health issues, and want to filter out sub-micron particles, then you should opt for a pleated, electrostatically enhanced filter at MERV-13. Keep in mind that the electrostatic filter needs to be changed more frequently than a mechanical filter in order to maintain efficiency.

How can I determine which is the best air filter for my needs?

When it comes to pleated filters, you need to consider which kind of pleated filter would be suitable for you. You can choose from a MERV-13, an electrostatically enhanced filter, or a MERV-8 or MERV-9 mechanical filter. If you have allergies or other health issues, use a long life MERV-8 or MERV-9 filter and use a portable HEPA air cleaner, with sufficient coverage, in the spaces in your home where you spend the most time.  

Why is airflow an important thing to consider when choosing an air filter for your home or condominium?

In a residential home or condo, there are a limited number of supply and return ducts. Therefore, it is crucial to have adequate airflow to help push the dirt towards the return duct where it gets trapped in the filter. Otherwise, if there is not enough airflow, the dirt will accumulate in stagnant areas and settle down. Without proper airflow, the air will not be cleaned effectively.

To get better indoor air quality, should I open my window?

Based on your location, opening windows may or may not be a good idea. If you are in a downtown city core, where there are a lot of vehicles and pollution, opening the window can bring in extra contaminants. If you are in the countryside, opening the window can bring in dust, pollen, or other irritants.

While opening a window can bring in fresh air and more oxygen, the decision to do so should be based on your own judgment of the air quality in your area. You can check the air quality reports from reputable sources like Environment Canada to get an idea of the pollution rating in your area.

Cheap air filters versus expensive air filters, what’s the difference? -Are higher quality air filters worth it?

Most residential air filtration units have a fan running at around 250 feet per minute, while some may run at 200 feet per minute. Therefore, they are less likely to damage the filter compared to commercial units. When choosing a filter, the physical construction of the filter itself is not as much of a concern as it is for commercial applications. 

It is essential that the filter is strong enough to prevent bowing or collapsing. A wire grid backing has the optimum strength when utilizing expanded metal (it should be a heavy gauge metal). The key factors to consider when choosing a filter are its efficiency and whether it’s a mechanical or electrostatic filter.

What’s the difference between a cheap MERV-8 air filter and a MERV-8-A rated filter? 

Some filters have a MERV-A rating that tells you the efficiency of the filter after any electrostatic charges are removed. If you purchase a cheap filter, you might only see a MERV rating, not a MERV-A rating, which means you cannot determine the actual efficiency of the filter. See air filter testing in Canada

For instance, if you see a MERV-8 rating, it means that the filter is not as efficient as a MERV-13 filter. However, not all MERV-13 filters are the same. Some MERV-13 filters could have a MERV-A equivalent rating of MERV-10, while others could have a MERV-A rating of 6. When a filter loses its electrostatic charge, it goes down in efficiency. Therefore, it is essential to check the MERV-A rating to see how low the filter efficiency is going to go after the charge weakens. If you want to buy a good filter, always check the MERV-A rating. This will give you an idea of how long the filter will maintain its effectiveness.

How often should you replace your air filters?

Using a standard residential air filter as an example, which is normally about one-inch thick, a 30/30 air filter should last about six months, a Dual 9 30/30 (one-inch-thick) can last over a year in a residential unit, compared to most standard pleated filters that will last only 3-4 months. A MERV-13 one inch pleated filter, should be replaced approximately every three months.

What are some of the signs that the filter needs to be replaced? 

One of the major indications that your air filter should be replaced is when you observe insufficient airflow in your house. This could mean that your house is not cooling down fast enough and requires maintenance. Residential HVAC units do not come with pressure drop gauges, so the best way to check their performance is through visual observation, for example if your filter is bowing, or by using a time-based evaluation provided by your air filter manufacturer. Read more on when to change your air filter

How can I extend the life of my air filter?

·   To extend the life of your filter, you need to minimize the amount of contaminants present in your home

·   Pets such as cats and dogs tend to generate more contaminants and can shorten the lifespan of your filter. Replace filters more often if you have pets. 

·   Opening windows is a good way to improve indoor air quality if the air outdoors is clean, but it may also affect the lifespan of your filter. If the air outside is polluted or dirty, it’s best not to open the windows to avoid introducing these contaminants inside the room and into your filter·       It’s important to note that pleated residential air filters cannot be cleaned, vacuumed, or washed

How do residential air filters impact indoor air quality?

Residential air filters remove contaminants by sucking them into the media of the filter and allowing clean air to flow into your home from the HVAC system. For the best air quality, use a MERV-13 air filter and change it every three months or so. You can further improve the air quality in your home by using a certified, portable HEPA air cleaner in rooms you use most often, living room, bedroom.  

What are the health benefits of using a good air quality air filter? 

Many people tend to feel drowsy and unwell when they are exposed to harmful particles in the air. Exposure to particles such as PM1 or PM2.5 can lead to various health issues such as allergies, bronchitis, asthma, and cardiovascular issues. The particles in the air can even cause heart and lung problems, and in some cases, even cancer. While it may be difficult to eliminate all submicron particles from a residential unit, a high-quality air filter will help reduce health risks caused by poor indoor air quality.

How do air filters contribute to a sustainable environment?

For houses and condominiums, a good option is to get a MERV-9-A or Dual 9 filter that is long-lasting and doesn’t require frequent disposal. 5 Ways to  Save Energy with Air Filters

Do residential air filters remove mould?

Residential air filters are not very effective in removing mould. Even a MERV-13 filter can’t eliminate a significant amount of mould spores. This is because the air needs to pass through the filter first, and there are not enough air changes in a residential unit. If you have mould spores or other similar issues, a portable unit is recommended. However, it’s important to note that using an air cleaner is only a temporary solution. The most crucial step is to identify and eliminate the source of mould.

Do air filters remove volatile organic compounds (VOCs)?

When it comes to removing volatile organic compounds (VOCs) in a home environment, only portable units with an activated-carbon filter have the ability to do so.

Do air filters remove odours?

As with VOCs, only activated-carbon air filters will remove odours adequately.

What is the most popular size of air filters for homes and condos?

The size of air filters for residential units is not standardized. The most common sizes are 16 inches x 20 inches, 16 inches x 25 inches, and 20 inches x 25 inches for household air filters. Verifying the precise dimensions needed for any HVAC system is crucial to guaranteeing a good fit and proper filtration performance.

Where can I buy a residential air filter in Canada?

Residential air filters are available in hardware stores and department stores as well as online. Canadian air filter expert Bernie Baier says, “To purchase a MERV-A rated filter that lasts the longest and maintains its efficiency, contact Camfil and ask for a 30/30 or a 30/30 Dual 9 or a MERV-13 filter in the size that is listed on the side of your air filter. You can buy them in bulk if you wish.”

To consult with an air filtration expert on the topics covered in this post or for further information, please use this contact form, and an air filtration expert from Camfil Canada will answer any questions you may have.

About Camfil Canada Clean Air Solutions

For more than 60 years, Camfil has been helping people breathe cleaner air. As a leading manufacturer of premium clean air solutions, we provide commercial and industrial systems for air filtration and air pollution control that improve worker and equipment productivity, minimize energy use, and benefit human health and the environment. Read more about Camfil Canada



Berni Baier, Canadian air filtration expert

Center for Disease Control (CDC)

American Society of Heating, Refrigerating and Air-Conditioning Engineers. (ASHRAE) 

Media Contact:

Phillip Ilijevski

Camfil Canada Inc.

T: 437-929-1161

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