How to Change Furnace Filter – a Simple DIY Guide

Changing your furnace filter is not the most glamorous home maintenance task, but you should not forget about it. A clean filter helps your HVAC system run efficiently, improves indoor air quality, and can even extend the life of your furnace. It is a quick and easy DIY project that anyone can do. Do you still feel puzzled about how to replace furnace filter? In this guide, we will walk you through the several steps of HVAC filter change.

Is furnace filter replacement really necessary?

Before you start the job, let’s talk about why changing furnace filter is so important. Your furnace filter traps dust, dirt, pollen, and other particles that circulate in the air. If you do not clean or replace it, you will sooner or later face one of these problems:

• Reduced airflow. A dirty filter makes your furnace work harder and increases energy bills.
• Poor indoor air quality. A clogged filter can’t effectively trap allergens and pollutants.
• System breakdowns. A dirty filter can cause your furnace to overheat or fail prematurely.

Experts recommend to change your furnace filter every 1-3 months, depending on the type of filter, your home’s air quality, and whether you have pets or allergies. Now, let’s get started!

Step 1. Prepare necessary tools.

Before you begin, make sure you have everything you need:

• A replacement filter. Check the size and type of new filter needed.
• A screwdriver if your furnace cover requires one.
• A flashlight to help you see inside the furnace.
• A vacuum or duster to clean around the filter area. 

Step 2. Locate your furnace filter.

Now, you must find your furnace filter. In most cases, the filter is located in one of these places:

• Inside the furnace. Look for a slot near the bottom or side of the unit.
• In the return air duct. It is often a large vent on the wall, ceiling, or floor.
• Behind a cover panel. Some furnaces have a panel that needs to be removed to access the filter.

If you are not sure how to remove furnace filter, check your furnace’s manual or look for a labeled slot or door.

Step 3. Turn off your furnace

Remember about safety – always turn off your furnace before changing the filter. Do one of these steps:

• Switch off the power button at the furnace.
• Turn off the thermostat.
• Shut off the circuit breaker if necessary.

Your furnace must not turn on when you’re working on it.

Step 4. Remove the old filter

Now, carefully slide it out of its slot. Take note of the direction of the airflow arrow on the side of the filter. This arrow shows which way the filter should face when you install the new one. After that, check for dust and debris buildup around the filter slot. If it’s dirty, use a vacuum or duster to clean the area before inserting the new filter.

Step 5. Inspect the old filter

You may learn helpful information. If it’s completely clogged with dirt and dust, it’s a sign that you need to change your filter more frequently. If it looks clean, you can make the replacement interval a bit longer.

Step 6. Insert the new filter

Now, it’s time to install the new filter. Use the correct size and type of filter. Insert it into the slot according to the airflow direction. If your furnace has a cover panel, reattach it securely. Double-check that the filter properly seats in its place.

Step 7. Turn your furnace back on

Once the new filter is installed, restore power to your furnace:

• Turn the furnace’s on/off switch back to the “on” position.
• Adjust the thermostat to your desired temperature.

When the furnace starts up, listen for any unusual noises or issues. If everything sounds normal, you have done a good job.

How to choose the right furnace filter

Not all furnace filters have the same properties.

• Fiberglass filters are affordable but only trap large particles. They are best for basic protection.
• Pleated filters are more effective against dust. They offer a good balance of cost and performance.
• HEPA filters are highly efficient – they remove small particles but may restrict airflow in some systems.
• Washable filters are eco-friendly but require regular cleaning.

Recheck the manual what filter type and size is right for your furnace. A wrong filter can reduce efficiency or even damage your system.

Final thoughts

Replacing your furnace filter is a simple task. You just need a few minutes every 1-3 months for it. Still, sometimes you may need professional help. If you can’t locate the filter or access it safely or your furnace isn’t working properly after changing the filter, contact a licensed HVAC technician to diagnose and fix a problem.