Best Filter For Lennox Furnace

If you have a Lennox furnace, you understand the importance of using the appropriate filter. You must be particular about the MERV rating and size of the filter you install in your Lennox furnace.

This is a review of some of the best filters you can use in your Lennox furnace to maintain a high Indoor Air Quality and keep your HVAC system free from contaminants.

Do All Lennox Furnaces have Filters?

All Lennox furnaces, like any other furnace, have filters. The filters are in the return air vent of the HVAC system. The return air vent of your HVAC system may be located anywhere.

The most common places of the return air vent of your HVAC are the side of the air handler, the ceiling, or even the wall. In most cases, the air filter is positioned inside a special unit.

The unit has a panel that covers the air filter. To access the air filter when you need to replace it, you will have to open the protective vent. You can either use your hands or a screwdriver to open the protective panel and access the furnace filter.

The furnace filters in all Lennox furnaces protect the HVAC system from damage. They trap small contaminants, including smoke, allergens, and pollen. The furnaces also help to maintain the quality of the air in the house.

Such contaminants can cause serious allergic reactions in people at home. Therefore, the filters in Lennox furnaces protect you as well as your HVAC system.

Which Way Does the Airflow in a Lennox Furnace?

The airflow in a Lennox furnace filter flows towards the furnace or air handler. It is important to note the direction of your furnace’s airflow because it determines how the furnace filter should be positioned.

When replacing your funnel filter, ensure that the lines drawn on the device are aligned with the direction of flow of the air. in other words, use the lines that are drawn on the filter to install it in your Lennox furnace correctly.

Where is the Filter Located on a Lennox Furnace?

The filter in your Lennox furnace is in the return vent of the system. This location is ideal to ensure that the filter effectively protects the blower and other components of the HVAC system from damage.

As is the case with all furnace filters, the filter in a Lennox furnace protects the entire system from contamination. Homes are full of small contaminants. The contaminants are in the form of pollen, allergens, dust, and smoke.

The small particles can find their way into your entire house if you do not have a good filter. If this happens, you will have to undergo costly repair works to keep your HVAC system in excellent working condition.

Thus, the furnace filter in your Lennox furnace prevents contaminants from getting to the blower in your HVAC system. Also, the filter helps to keep the air in your indoor space clean and free of contaminants.

Such contaminants can trigger reactions in people who have allergies. Therefore, the positioning of the filter in Lennox furnaces is perfect for the achievement of these objectives.

What is the Right Furnace Size for a Lennox Furnace?

You can determine the right furnace size for a Lennox furnace by looking at the old filter. Lennox furnace filters have their sizes marked on the surface. When you need to purchase a new one, you only need to look at the old furnace filter to get the right size.

Alternatively, you can consult a certified HVAC technician to help you determine the right furnace size for your Lennox furnace. Any certified technician can help you get this information in an instant.

Using the right size of a furnace filter is critical. Although some people argue that it is possible to cut your furnace filter, this is not advisable. It is wiser to purchase a furnace filter of the right size than having to cut your filter so that it can fit in your HVAC system.

The Best MERV Rating for Lennox Furnace Air Filters

The Minimum Efficiency Reporting Value or MERV is an impressive figure that is used to measure the level of effectiveness of furnace filters.

Furnace filters comprise materials that are interwoven to leave very tiny holes. The interweaving of the materials increases the surface area of the filters. This raises the percentage of small particles that are trapped by the fibers of the filter.

The small holes allow the air to pass. If the air does not pass through your furnace filter properly, the entire HVAC system may get damaged. You will also have to pay for additional power costs because the blower of the system will be forced to overwork to pass the air through the thick filter.

Filters with a MERV rating of at least 13 are ideal for use in Lennox furnaces. The highest MERV rating is 16. Therefore, furnace filters with a MERV rating of 13 are quite thick.

Such filters can attract and trap up to 97% of all the particles in the house. You will rarely get an allergic reaction if you live in a home with pets but a furnace filter with a MERV rating of 13 is installed in the HVAC system.

How Often should you Change the Filter for a Lennox Furnace?

At most, you should change the filter for a Lennox furnace after every three months. This is what is recommended in many brands of furnace filters.

It means that after every three months, you must open the unit that holds the filter in your HVAC system and remove the old and full filter.

You will then have to install a new one for the system to work without any hiccups. In practice, this may be more frequent than this. It all depends on the circumstances under which you use your furnace filter.

If you have a furnace filter with a high MERV rating, the chances are that you will have to replace it sooner than after the recommended time of three months.

Such furnace filters attract and capture vast amounts of contaminants. They will be full of pollen, allergens, and other small particles that have diameters that range from 0.3 to 1.0 microns within a short time.

If your furnace filter is full, you will realize that the Indoor Air Quality suddenly reduces. If this happens, it may be time to replace your Lennox furnace filter.

How to Choose the Best Filter for a Lennox Furnace

Choosing the best filter for your Lennox furnace is the most important thing that you should do. If you get the wrong furnace filter, the chances are that you will be forced to incur the costs of repairing a damaged HVAC system.

Having the wrong type of furnace filter may either force your HVAC system to overwork or let small particles through to your ductwork and the entire airspace in your house.

Here are a few things that you should consider when choosing the best filter for a Lennox furnace.

  1. Size. The size of the furnace filter is critical. Ensure that you get the right size furnace filter to enjoy the highest quality of air in your home. You can determine the correct size of the furnace filter to use by either consulting a certified HVAC technician or checking that of the old filter in your Lennox furnace.
  2. MERV Rating. The MERV rating of your furnace filter determines how effective it is in collecting contaminants from the air. Generally, choose furnace filters with a MERV rating of at least 13 for use in your Lennox furnace. Remember that the higher the MERV rating, the more frequently you may have to replace your furnace filter.
  3. Thickness. The thickness of a furnace filter determines the ease with which air currents can pass through. Very thick furnace filters with activated carbon layers and interwoven fibers will drastically minimize the amount of air that can pass through. This may force your blower to overwork to ensure a steady supply of air in the home.

How to Install a Lennox Air Filter

Installing a Lennox air filter should never be a complicated task. All air filters have small arrows marked on their sides. The small arrows are supposed to guide you when installing the furnace filter.

Here is a simple step-by-step guide on how to install a Lennox furnace filter.

  • Locate the position that the air filter is installed in the furnace.
  • Use a screwdriver or your bare hands to remove the panel that protects the furnace filter.
  • Remove the old filter from the protective unit.
  • Install the new filter by placing it so that the lines on the filter are aligned with the flow of air in your Lennox furnace.
  • Close up the unit properly.

Best Filter For Lennox Furnace

1. Lennox Healthy Climate X8788 MERV 16 Filter

The Lennox Healthy Climate X8788 furnace filter is one of the best models you can use in your Lennox funnel. For starters, this filter has a very high MERV rating of 16.

This high MERV rating is high enough to capture all forms of contaminants, including dander, allergens, smoke, odor, and dust. The surface of the filter comprises interwoven fibers that increase the surface area.

This means that the air filter can effectively capture up to 95% of all the small contaminants that measure from 0.3 to 1.0 microns in diameter.

You will enjoy using this filter in your Lennox furnace because of its longevity. This filter is supposed to last for about six months. However, remember that at times you may have to replace it sooner than after six months. This may happen if the furnace filter collects a lot of contaminants within a very short period.


  • A high MERV rating of 16 ensures high-quality indoor air
  • Long-lasting filter because it requires replacement after about six months
  • Easy to install because of its size of 25’’ by 26’’ by 5’’


  • The furnace filter is quite thick and may force your blower to strain when moving the air

2. Lennox X6675 MERV 16 Media Air Cleaner

The Lennox X6675 is a versatile and beneficial air filter designed for a Lennox furnace. One of this air filter hallmarks is that you do not have to worry much about installing it. It comes in a size that is perfect for any standard HVAC system.

However, you may need to call a technician to install this furnace filter for you if you are not conversant with the process of installing an air filter or there is a technical problem in your Lennox furnace.

This furnace filter is ideal for eliminating odors in the house. If you have pets, the small hair particles that they shed may cause a foul odor in the house. Having this air filter is the perfect solution to this problem.

It has a surface that is coated with activated carbon and a coconut saturate. This surface is powerful enough to attract and capture the small particles that may cause odors around the house.


  • Effective removal of odors because of its coconut and carbon-activated surface
  • Its high MERV rating is s+uitable for use in a Lennox furnace
  • Easy to install because it is of the perfect size


  • You may have to replace it sooner than the recommended six months

3. Lennox Corporation X7935 20X20X5 MERV 16 FILTER

The Lennox Corporation X7935 furnace filter has the right MERV rating for use in a Lennox furnace. It is recommended that one uses an air filter of 13 MERV rating in a Lennox furnace.

Thanks to the high rating of 16, this filter can effectively trap all minute particles, including dander and smoke, when it is installed in the Lennox furnace.

Its surface is made of perfectly interwoven fiber material that increases the surface area. This makes the filter very effective in capturing large amounts of contaminants within a short period, thus keeping your house clean and the HVAC system safe.

Although this filter has a high MERV rating and is powerful in capturing small particles, it is available in a pack that contains a single piece. You will have to incur additional costs of purchasing a new pack soon. Luckily, when properly installed, this filter can last for as long as a year.


  • The surface is made of an interwoven micro-glass material that increases the surface area
  • It remains effective for as long as one year
  • The filter has a high MERV rating of 16


  • There is only one piece in the pack

4. Lennox Carbon Coated X6672 Healthy Climate MERV 16 Filter

If you are looking for an ideal air filter for use in multiple Lennox furnace surfaces, consider using the Lennox Carbon Coated X6672.

This air filter is designed to be easily installed and used in multiple Lennox furnaces that are compatible. Thus, you will enjoy value for your money because you will not have to purchase different filters for specific Lennox furnaces in your home.

The surface of the Lennox Carbon Coated X6672 has been specially treated to trap microorganisms. This is beneficial because the filter will trap all microorganisms that can use flu and related complications.

More so, the surface is electrostatically charged so that it can attract large amounts of contaminants and keep the air in your house free of pollen, dander, and allergens.


  • The surface of this filter has been treated to trap microorganisms
  • Ideal for use in multiple Lennox furnace products
  • The air filter has an electrostatically charged surface


  • It comes in a pack of two pieces only

5. Lennox X6675 Carbon Clean 20 x 25 x 5 Inch MERV 16 Efficient Air Filter

If you are looking for a furnace filter that is powerful enough to remove odors from your home, get the Lennox X6675. Its carbon-coated surface can successfully trap and remove all the small particles that cause odors in the home, including hair particles from pets.

The furnace filter is perfect for use in your Lennox furnace because it has a high MERV rating of 16. Lennox furnaces require filters that have a high MERV rating of over 13 to function properly.

The only notable drawback of using this furnace is that it is not compatible with all the different Lennox furnaces. You may have to incur additional costs to get a new air filter if this one is not ideal for use in your Lennox furnace.


  • The air filter is effective for removing odor because the carbon-coated surface
  • High MERV rating of 16
  • The air filter can trap even minute particles that measure 0.3 microns in diameter


  • It is not compatible with a broad range of Lennox furnaces

6. X6673 Lennox 20x25x5 Merv 11 Filter Media 2 Pack

One of the most advantageous reasons for using this furnace filter is that you are assured of its quality. it is manufactured by Lennox and not another third party. Also, the furnace filter is of nominal size of 20’’ by 25’’ by 5’’. You will find it easy to install it in your Lennox filter.

It performs well in protecting your HVAC system from damage that arises when dust particles find their way through the ductwork. This furnace filter is also quite reliable when you need a device that keeps the air in your home clean and free of contaminants.

However, this furnace filter has a relatively low MERV rating of 11. Most of the brands that are compatible with Lennox furnace have high MERV ratings of about 16. Nevertheless, it works just fine to keep your indoor air quality high and prevent damage to your HVAC system.


  • The furnace filter is manufactured by Lennox
  • Easy installation because it is of nominal size of 20’’ by 25’’ by 5’’
  • Effective in trapping small particles that measure down to 0.3 microns in diameter


  • It has a relatively low MERV rating of 11


Lennox furnaces, like any other type of furnace, need filters to function correctly. However, it would help if you got filters with MERV ratings of at least 13 for your Lennox furnace. Installing the filter in your Lennox furnace need not be a big deal. You only need to ensure that the filter lines corresponding to the direction of flow of the air in your system.