Where is the Furnace Filter Located?

For most homeowners, the furnace is a mysterious beast tucked away in the basement, or some other hidden corner of the house.

One critical component of the furnace, the furnace filter, is often overlooked, despite its importance for the overall performance and longevity of your heating system.

If you’re scratching your head wondering, “Where is the furnace filter located?” you’re in the right place! Let’s delve into this critical aspect of your home’s HVAC system.

What is a Furnace Filter?

The furnace filter, or air filter, plays a crucial role in maintaining indoor air quality. It captures airborne particles like dust mites, pet dander, and other allergens, preventing them from circulating throughout your home.

A clean furnace filter also facilitates proper air flow, enhancing your system’s energy efficiency and keeping your energy bills in check.

Where is the Furnace Filter Located?

Furnace filters can be found in a few places, depending on the type of furnace and your home’s specific setup. Typically, they’re located in the upper blower compartment, return ducts, return air grills, or in vertical HVAC systems.

Upper Blower Compartment

In many homes, you’ll find the furnace filter in the upper blower compartment of the furnace.

Location of the Upper Blower Compartment

The upper blower compartment is typically found next to the heat source in your furnace system, whether that’s electric coils or a gas burner.

How to Access the Upper Blower Compartment

Accessing the upper blower compartment usually involves removing a metal cover or panel. This may involve a safety switch that turns off power to the unit when the cover is removed.

Size and Type of Filter in the Upper Blower Compartment

Furnace filters come in several sizes and types. Measure your existing filter before purchasing a new one to ensure the filter fits correctly.

How to Clean or Replace the Filter in the Upper Blower Compartment (list form)

  1. Turn off power to the furnace.
  2. Remove the cover from the upper blower compartment.
  3. Slide out the dirty filter. Note the airflow arrow on the filter frame.
  4. If you have a disposable filter, replace it with a new one. For reusable filters, clean it according to the manufacturer’s instructions.
  5. Slide the clean filter back into the slot, ensuring the airflow arrow points towards the furnace or air handler.
  6. Replace the compartment cover and restore power.

Return Ducts

In some cases, furnace filters may be located in return ducts, where air is pulled back into the furnace for reheating.

Location of Return Ducts

Return ducts are generally found in walls or floors and may be centralized or spread throughout the house.

Inspecting Return Ducts for Dirty Filters

Remove the grill cover on your return vents to inspect for dirty filters. In some homes, each return vent may have its own filter.

Cleaning or Replacing Filters in Return Ducts

Cleaning or replacing filters in return ducts involves similar steps to those used for the upper blower compartment. Be sure to have the right size and type of furnace filter for your specific return ducts.

Return Air Grills and Vertical HVAC Systems

Some homes, particularly those with vertical HVAC systems or central air units, have furnace filters located at return air grills.

Location of Return Air Grills and Vertical HVAC Systems

Return air grills are often found on interior walls, and in vertical HVAC systems, the filter may be housed in a slot within the air handler or attached to the unit with air moving up.

How to Access Return Air Grills and Vertical HVAC Systems

Accessing these filters involves removing the grill cover or accessing the filter slot in your central air unit. Always turn off power before attempting to remove a filter.

Size and Type of Filters for Return Air Grills and Vertical HVAC Systems

As with other locations, measure your existing filter before purchasing a new one, and ensure you select the correct type for your system.


Locating your furnace filter can feel like a scavenger hunt, but with these tips, you’ll be on your way to better indoor air quality and improved energy efficiency in no time.

And if you’re ever unsure or uncomfortable, don’t hesitate to reach out to a qualified HVAC professional for guidance or assistance. Happy hunting!

About Roy Cohen

Roy Cohen has a burning passion for heating, cooling, and ventilation. He aims to help you save money on expensive repairs and bring you the best HVAC products. He has years of experience behind him in HVAC repair and garage maintenance.

You can find Roy at his LinkedIn or his email: [email protected]

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