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John Mulder Heating & Air Conditioning Ltd

Air Filters

Air filters are essential components of your heating and cooling system. They help improve the quality of your home’s air and keep your system performing at peak efficiency. The most common air filters are standard disposable cartridges, but advanced filtration systems and air cleaners are also available.

When to Change Air Filters

Standard, one-inch disposable air filters should be changed every three months. However, if anyone in your family suffers from allergies, or if you have pets or dust buildup in your home, you might want to change your filters every month or so. Advanced filtration systems have longer life spans and are usually maintained by HVAC professionals.

How to Change Your Air Filter

The process for changing standard disposable filters is fairly straightforward and involves just a few steps:

Locate your air filter Air filters are typically located in your system’s return air vent, which might be on the ceiling, wall or on the side of your furnace or air handler. Your air filter might also be housed inside the unit. If this is the case, you may have to remove an access panel to get to the filter.

Remove the air filter from its housing Simply open the return and pop out the old filter. If there is no filter in return, measure the length and width of the space, so you’ll know what size filter you’ll need for replacement.

Note the size printed on the air filter frame If you removed an old filter, check its size so you can be sure you have the correct filter for replacement. If you have any questions about the size you need, you can refer to the owner’s manual for your furnace or air handler, or contact your local Lennox® Dealer.

Install the new air filter Securely slide the new filter in place of the old one, making sure you follow the arrows printed on the sides of the filter frame. These arrows point to the direction of the airflow, which should be toward your furnace or air handler.

Get help from your lennox® dealer If you have any questions about where your filter goes, or how to install a new one, your local Lennox® Dealer can help. If you have already replaced your filter, and your system makes excessive noise, contact your Lennox® Dealer to address the problem.

Consider More Advanced Filtration

Lennox® offers a wide variety of filtration products, including high-performance air cleaners that remove small, allergy-aggravating particles that standard filters can’t stop.

Want to Know More?

Check out our Comfort Matters blog articles on this topic:


From the industry’s most effective air purifier to the #1 rated filtration system*, there's an innovative solution you can feel good about.


Explore Purification Solutions

Whole-home Solutions for Complete Peace of Mind

Healthy Climate® air purification and filtration systems are designed to work with your central heating and cooling system. They improve the air throughout your entire home—not just in individual rooms—without producing ozone, a known lung irritant*.

The Most Effective Way to Improve Your Air

The PureAir™ air purification system is the only single indoor air quality system to combat all three classes of contaminants.

Allergy-aggravating particles such as dust, pollen and pet dander
Mold and germs that grow and reproduce in damp places, such as basements and crawlspaces
Odours and chemical vapours from paints, cleaning supplies and additives used in carpeting and furniture
benefits of using air filters

Multiple Technologies Working Together in One Powerful System

PureAir™ reduces and removes contaminants with hospital-grade filtration and a powerful air purification technology called photocatalytic oxidation (PCO).

Other Smart Solutions for a Healthier Home

The Carbon Clean 16® media air cleaner is the #1 rated, professionally installed, whole-home filter as rated by a leading consumer magazine*.

Best brand for air filters

A Bright Solution for Controlling Germs

Healthy Climate germicidal lights use intense rays of ultraviolet light to control contaminants.

Germ controller image

A Lennox® PureAir™ whole-home air purification system improves indoor air quality better than any single system you can buy. Many technologies only combat one or two categories of air contaminants, and often only in a single room. The PureAir air purification system is the only single indoor air quality system to combat all three classes of indoor air contaminants—particulate, bioaerosols and Volatile Organic Compounds (VOCs). The PureAir air purification system reduces indoor air pollutant levels through a combination of hospital-grade filtration and a contaminate removal process called photocatalytic oxidation (PCO). The process involves three steps. Step one, the Carbon Clean 16® filter captures particles and bioaerosols as small as 0.01 micron, removing them from the airstream. Step two, as the odor-and-chemical-vapor-filled airstream flows through the PCO cartridge, the airstream is exposed to the catalytic surface (titanium-dioxide-coated PureAir cartridge). Step three, the light energy from the UVA lamp and catalyst work together to break down odours and chemical vapours into harmless carbon dioxide and water. Unlike other air purification products on the market, the PureAir system does not produce any ozone as a by-product and actively works to reduce ozone, a known lung irritant.

PureAir S Air Purification System

Sensing and communicating, and cleans the air in your home better than any other single system you can buy

Price Guide   $$$$

PureAir Air Purification System

Cleans the air in your home better than any other single system you can buy

Price Guide   $$$

Healthy Climate Carbon Clean 16® Media Air Cleaner

The healthiest media filter for ozone reduction and filtration of allergens and germs

Price Guide   $$

Healthy Climate® 13 Media Air Cleaner

The healthy-household media filter for families wanting protection from viruses and bacteria

Price Guide   $

Healthy Climate 11 Media Air Cleaner

The everyday media filter for allergen-reduction that’s ideal for households with pets

Price Guide   $

Healthy Climate High-Efficiency Particulate Air (HEPA) Filtration System

Hospital-grade filtration performance

Price Guide   $$$

Healthy Climate UV Germicidal Lights

Highest UV light intensity on the market!

Price Guide   $

*Leading consumer magazine, January 2012. Based on the published CADR, which is a standardized measurement system to determine the cubic feet of clean air produced per minute.


**U.S. Environmental Protection Agency, "Ozone Generators that are Sold as Air Cleaners: An Assessment of Effective and Health Consequences," August 2006


***According to Title 24 Code in California, MERV 11 filters cannot be used in new equipment installs. Code dictates a new system shall be provided with air filter(s) having a designated efficiency equal to or greater than MERV 13 when tested in accordance with ASHRAE Standard 52.2.

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