Changing Furnace Filters: A Step-By-Step Guide For Homeowners

Changing the air filter in your fuel-air furnace is a simple task that can save you money, safeguard your health, and extend the life of your furnace. Furnace filters protect your furnace from dust, hair, and other debris that gets drawn in through the cold air return ducts. If dirt gets into the furnace, it can increase fuel consumption and maintenance costs while also reducing furnace life. Changing your furnace filter is also a quick and easy method to keep your indoor air clean.

Locate the furnace filter

Locating your furnace is the first step in finding your furnace filter. Most furnaces are installed in the centre of your home, either in a utility closet or downstairs in the basement. If your home doesn't have a basement, it may be in a crawl space or the attic. Once you've located your furnace, you can begin searching for the furnace filter.

The location of your furnace filter depends on the type of AC unit and how your furnace was installed. Furnace filters are typically found within the blower compartment, which can be accessed through a metal door or hatch on the bottom half of the furnace. It may also be located in a sliding compartment near the air handler component of your furnace or on a rack attached to the furnace's side. The filter will be positioned to capture dust, pollen, and other airborne particles as they pass through your HVAC system.

If you have a horizontal HVAC unit, the furnace filter will usually be found on the intake side, slid into a rack. For vertical HVAC units with upward-moving air, the filter can be found in the bottom door, where the blower is located. You will need to open both the top and bottom doors to access the filter. Conversely, if your vertical HVAC unit has downward-moving air, the filter will be located in the top door, where the blower is situated, and this type of furnace may require two filters.

Additionally, the furnace filter can be found in one of the following locations within your HVAC system:

• Return Air Vent: In some HVAC systems, the filter is positioned behind the return air vent, typically found on the floor, wall, or ceiling.
• Furnace Blower Compartment: The filter is often placed near the furnace's blower, in a slot where it slides in and out, usually between the air intake duct and the furnace.
• Air Handler: For systems with a separate air handler, the filter is commonly found in the handler unit, close to the return duct.

If you're unable to locate the furnace filter, you can follow the airflow path from the return vent to the furnace or air handler. Alternatively, you can refer to your HVAC manual or seek assistance from a professional technician.

Remove the old filter

To remove the old filter from your fuel air furnace, start by turning off your furnace. This is an important safety step to prevent the furnace from turning on while you are working. Set the thermostat to the "off" position.

Next, locate the furnace and open it to access the filter. There will be a door on the furnace that either swings open or slides off. Open or remove the door to reach the filter inside. If your door slides off, you can usually do this by lifting it up and setting it aside.

The filter is typically located at the air return duct or the entrance to the blower chamber. There may be a cover over the filter that you will need to pull off. Look for the vents where the air enters the furnace system to help you locate the filter.

Once you have located the filter, slide it out carefully with both hands. If there is resistance, check for a locking mechanism and slide it out of the way to release the filter.

Now, hold the filter up to a light source to inspect how dirty it is. If no light shines through, it's time to replace the filter. Disposable filters will have a cardboard frame, while reusable filters will have a plastic or metal frame.

Check filter size

Checking your furnace filter size is a crucial step in maintaining your furnace. Furnace filters come in a variety of sizes, and it is important to get the right size for your furnace. Here are some detailed instructions on how to check your furnace filter size:

Locate the Filter: The first step is to locate the filter in your furnace. The filter is usually found near the air return duct, the blower compartment, or the side panel of the furnace. You may need to open a door or remove a cover to access the filter.

Remove the Filter: Once you have located the filter, carefully slide it out of its slot. Most filters can be easily removed by sliding them out, but some may have a locking mechanism that needs to be released before removal.

Check the Frame: The filter size is typically printed on the frame of the filter. Look for measurements in inches, such as 1", 2", or 3". If the dimensions are not printed on the frame, you can measure the filter yourself with a measuring tape. Be sure to round up to the nearest half inch.

Note the Dimensions: Write down the dimensions of the filter so that you can purchase the correct size when shopping for a replacement. It is important to get the exact size to ensure a proper fit.

Consider the Thickness: Furnace filters come in different thicknesses, such as 1", 2", 3", or larger. The thickness of the filter is an important factor in determining how often it needs to be replaced. Thicker filters generally last longer than thinner ones.

Check for Damage: While checking the size of the filter, also inspect it for any damage. If the filter is torn, bent, or damaged in any way, it will need to be replaced. A damaged filter will not function properly and can compromise the performance of your furnace.

Compare with Owner's Manual: Finally, you can refer to the owner's manual of your furnace to confirm the correct filter size. The manual should provide specifications and recommendations for the type and size of filter that is suitable for your furnace.

It is important to note that using the wrong filter size can damage your furnace and reduce its efficiency. Therefore, taking the time to check the filter size and purchasing the correct replacement is essential for the proper maintenance of your furnace.

Insert the new filter

Now that you've located your furnace and removed the old filter, it's time to insert the new one.

First, check the size of your new filter. The filter size should be printed on the side of the frame. If not, measure the filter yourself, rounding up to the nearest half-inch. It's important to get a filter that's the same size as the old one to ensure a proper fit.

Next, locate the arrow on the new filter, which indicates the airflow direction. This arrow should point toward the furnace or air handler. Slide the new filter into the slot, ensuring it's facing the correct direction. The filter should have an arrow pointing toward the furnace's blower motor.

Once the new filter is in place, secure any covers or panels that go over it. Then, close or replace the door panel of the furnace. If you removed the door panel earlier, swing the furnace's access door closed or slide it back on.

Now your furnace is ready to be turned back on. Set the furnace's thermostat back to the "on" position, and your furnace will be protected from loose debris by the new filter.

It's a good idea to make a note of the date you changed the filter and set a reminder to check it again in a month. This is especially important if you have pets or run your furnace regularly, as you may need to replace the filter more frequently.

Turn the furnace back on

Once you have finished replacing the filter, it's time to turn the furnace back on.

First, you will need to close or replace the door panel of the furnace. Swing the furnace's access door closed or slide it back on if you removed it.

Now, turn your furnace back on. Set the furnace's thermostat back to the "on" position. Your furnace will now be protected from loose debris by the new filter and is safe to run as normal.

You might want to make a note of the date you changed the filter to remind yourself to check it again in a month. Checking your filter every month and any time you notice dust building up in your home is a good idea, especially if you have furry pets or run the furnace very regularly.

If you need assistance with any furnace maintenance or repair, it is always best to call a professional for help.

Frequently asked questions