How to Quickly and Easily Replace Your Furnace's Filter: Eleven Easy Steps (with Pictures)

1. 1

   Before you check or replace the filter, the furnace must be turned off. Put the thermostat in the "off" position to turn the heater off. While you are checking or replacing the filter, the furnace won't turn on accidentally.

   • If the furnace is turned on without a filter, it could potentially damage the home by sucking in a lot of loose debris.
   • Instructions on how to change the filter in your furnace can be found in the device's user guide.

   Monthly filter checks can help you determine if you need to replace it. Disposable filters should typically be changed every few months. Filter deterioration is accelerated by the presence of furry pets or continuous furnace use.

2. 2

   Disengage the furnace by removing the door panel (by opening or sliding it). In either case, your furnace will have a door that opens by swinging out or slipping off. If you need to get into the furnace, you should either open the door or take it off. [1]

   • Most sliding doors can be removed by simply being lifted until they release and then being set aside.

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3. 3

   Find your furnace's filter and take off the cover you see above it. Filters are typically installed at the air return duct or blower chamber inlet. There is often a second cover over the filter that needs to be removed. [2]

   • Locate the filter close to the air return duct or the blower chamber entrance, which is where air enters the furnace system.

4. 4

   Take out the used filter and examine it under a microscope. Inspect the filter by gently removing it with both hands. Look at it under a bright light to see how dirty it is and whether or not it needs to be replaced. [3]

   • There may be a locking mechanism preventing the filter from sliding out if you encounter any resistance. If you find such a system, you can unlock the filter by sliding the lock to the side.

5. 5

   If you're unable to see through the filter, you should get a new one. When no light comes through the filter when you hold it up to a light, it needs to be replaced. Maintaining proper airflow through the furnace and preventing it from overheating requires regular filter changes. [4]

   • Cardboard supports the filter paper in disposable models. Filters with plastic or metal frames can be cleaned and reused multiple times before needing to be replaced.

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1. 1

   Measurements can be found on the cardboard support structure of the used filter. There will be a size indication on the disposable filter's frame. Write it down and take the measurements with you when you go to purchase a replacement filter. [5]

   • To ensure you purchase the correct replacement filter, check the owner's manual or measure the old one if it does not have the dimensions printed on it.

2. 2

   Invest in a properly sized replacement filter. Go to a hardware or home improvement store to pick up a replacement filter. You can determine the correct size replacement filter by comparing it to the old one's measurements. [6]

   • Cardboard-framed fiberglass furnace filters are the most inexpensive disposable option. This type of filter is meant to be changed every few months as it catches large dust particles. In order to filter out even the tiniest particles of dust, pollen, and dirt, you can invest in a disposable pleated filter, which is only a little more expensive. From four months to a full year, these filters are built to last.

   A highly efficient particle air (HEPA) filter is a good idea if you or a family member suffers from allergies. These filters are antimicrobial and made to prevent the growth of microorganisms like mold, mildew, fungi, yeast, and algae. You can buy them once and use them again and again.

3. 3

   There should be an arrow on the filter indicating the correct orientation. On your new filter, you'll find an arrow indicating the direction of airflow. If you look for the arrow, you'll know which way to insert the filter into the furnace.

   • Filters for residential furnaces are designed to work in a unidirectional airflow, keeping them from collapsing under the weight of the dust and debris they collect.

4. 4

   Covers should be replaced after the filter has been slid into place. Place the new filter into the furnace with the arrow pointing toward the blower motor. If you used a filter cover to access the filter, replace it now. [7]

   • If the filter is installed upside down, airflow is restricted, causing the furnace to overheat and shut off. This can also be brought on by a dirty filter, so be sure to check it once a month and swap it out whenever it gets too grimy to function properly.

5. 5

   Put the furnace door back on, or shut it, before proceeding. After closing the furnace's access door, if you removed it, slide it back on. After this, you can safely use your heating system for at least another month. [8]

   • Keep in mind that you'll need to change the filter more frequently if you have furry pets or if you frequently use the heating system. Be sure to change the filter once a month, or whenever you notice increased levels of indoor dust.

6. 6

   Get the fire going again. After switching out the filter, remember to turn the thermostat back to "on" for the heater. The filter will keep the furnace free of dust and other particles, so it can function normally.

   • If you want to remember to check the filter again in a month, you could write down the date you last changed it.

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