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Where is My Furnace Filter Located

By April 16, 2021April 26th, 2021Furnace
large metal furnace compartment next to the blower, near the bottom of the door or on the side of the door. Now, it depends on how the furnace was installed as to where the filter is located:

In the Northwest and colder states, most homes have a furnace. We want our homes to stay warm in the winter and frigid temps and need to make sure the furnace is working well. Just like an air conditioning unit needs a filter changed out, so does the furnace. Where is my furnace filter located? It is located in the metal compartment near the floor or side of the door.

Let’s take a look at why you need to know where the furnace filter is located, background information, location, how it works, how to choose one and replace, maintenance, life of the HVAC and when to call a professional.

Why You Need to Know Where the Furnace Filter is Located

The furnace filter needs to be changed out every 90 days, especially when the furnace and air conditioner is being used. In order to do this, you need to know where it is located. A furnace, just like an AC unit needs maintenance in order to keep it running for as many years as possible. It is not cheap to replace so taking care of it is essential.

Background of the Furnace

The furnace is to keep people warm in their homes. It runs on propane, natural gas, electricity, or heating oil. It depends on the type of furnace you have as to what energy/fuel it needs to run. If the home has central air, then the furnace usually shares the air handler with the air conditioner.

Location of the furnace

Location of the Furnace

There are many places in the home where the furnace may be located. As mentioned above, if you have central air then the furnace may share the same air handler.  Also, it may be located in the garage, attic, basement, crawl space, or utility closet.  Usually it is very close to where the washing machine and water heater are in the home.

Where the Furnace Filter is Located and How it Works

The furnace filter is located in the large metal (sometimes plastic) furnace compartment next to the blower, near the bottom of the door or on the side of the door. Now, it depends on how the furnace was installed as to where the filter is located:

If you have a horizontal HVAC unit, the furnace filter will be located on the intake side and slid into a rack.

Maybe yours is a vertical HVAC unit with air moving upwards.  The furnace filter will be in the bottom door and this is where the blower is. To get to the filter, open both the top and bottom doors. Lastly, if the unit is a vertical HVAC unit and the air moves downward, your air filter will be in the top door.  This is also where the blower is located and this type of furnace or AC unit may also require two filters.

It is important that the filter is clean and works properly. It is essential that the air passes through and stops the pollen, dust, and other air borne particles. Then, the rest of the air pushes up to a higher compartment and a heat source warms it.

Furnace filter and air filter are the same

Furnace Filter and Air Filter Are the Same

Did you know that if your air conditioner and furnace share the same air handler then they are using the same filter? So it is important that you check the filter every 30 days. Also plan on changing it every 90 days unless your home has pets and a lot of dust that is caught in the filter.

How to Choose and Replace a Furnace Filter

The filter you use will have a MERV rating. This means Minimum Efficiency Reporting Value. A minimum MERV value of 7 is the ideal value to have in the home. Merv 1-6 is too low, the above 13 is too high unless a professional says your home needs it.

Before you head out to the store or order it online, look at the size of the one currently in there so you have the correct size. If you don’t have the right size, it won’t work efficiently.

Here is a great video about how to replace the filter:

I Bought the Home and the Furnace Doesn’t Have a Filter

It is recommended that if there is no filter, you buy one that is the appropriate size. Not sure what that is or if the furnace is clean? Hire a professional to take a look at the furnace and make sure it is working correctly. He/she will also be able to tell you what size filter to purchase and the furnace is working properly.


As mentioned earlier, check the filter at least every 30 days. You want to make sure you have a clean filter so it catches the dirt and helps the air flow properly through the home. While you are checking the filter, you may notice the air handler is leaking water.

This could be due to many things. Examples are a clogged condensate drain line, the drain pan is damaged or rusted, the condensate pump is broken, the air filter is not clean, or the refrigerant is lowIt is important to have this checked. Check the outdoor HVAC unit for leaves after storms. They often are caught in the fans and need to be pulled out.

Life of the HVAC and changing the air filter

Life of the HVAC and Changing the Air Filter

If you are finding that the home is not staying cool or dust is accumulating, check the filter first and see if it is the right size and clean. If that doesn’t seem to fix it, then call a professional.  He/she can let you know if there is a small repair or if it is time to replace the unit. Fortunately, most systems last about 10-15 years. However, it does depend on the environment and other things such as keeping up with maintenance.

Not sure when the perfect time is to change the air filter? Usually spring. This is because the winter storms and temperatures have left us and we are upon spring. Spring temperatures allow you to go outside and take a look at what is going on in the yard and on the home. You want to do this before summer temperatures set in so you are not roasting in the home if there is an issue.

No matter where the furnace or HVAC system is located, cleaning the area out is important. You don’t want particles in pulling into the system. As mentioned earlier, the furnace can be located in many places in the home. If one of those places is the crawl space, you want to make sure you clean that area each year. This is because mold and fungi can grow in there or worse, rodents can make nests.

When to Call a Professional

Call a professional if you need help finding the furnace filter, need help changing it out, help with maintenance or need a repair or diagnosis. Professionals are trained to help you!


The furnace filter needs replacing possibly every 90 days or less depending on the environment, pets, and dust in the home. Remember, keeping up with this will help you get the most amount of years out of your furnace and save you money.  We can take a look at your furnace while doing a home inspection in Lacey, Washington. Think you might need our services? Comment below!

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