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Introduction
Changing the air filters in your home's HVAC system regularly is one of the most important maintenance tasks you can do. Clean air filters ensure good indoor air quality by trapping dust, dirt, pollen, and other particles from circulating through your home. They also help keep your HVAC system working efficiently by allowing proper airflow. If filters get clogged with debris, it forces your system to work harder, wasting energy and potentially damaging components.
Replacing filters is a relatively quick and easy DIY task that anyone can do themselves with some basic guidance. In this article, we'll walk through the step-by-step process for accessing and changing out the air filter in a typical residential HVAC system. We'll cover the different types of filters, how often you should change them, what materials are needed, proper installation, restarting your system, and more. With just a bit of time and effort, you can keep the air in your home clean and your HVAC system running at peak performance.
Types of Air Filters
There are several common types of air filters used in home HVAC systems:
Pleated Filters
Pleated filters are the most basic and inexpensive type of filters. They are made of loosely-woven mesh or cotton material that traps larger particles. Pleated filters need to be replaced frequently, about once every 1-3 months. They do a decent job filtering out things like dust and pet hair, but do not capture smaller particles.
Electrostatic Filters
Electrostatic filters use static electricity to attract and trap particles. The fibers in the filter are positively charged, which pulls in negatively charged particles like dust and pollen. Electrostatic filters are more efficient at catching small particles compared to pleated filters. However, they must be replaced about every 3-6 months.
HEPA Filters
HEPA (high-efficiency particulate air) filters are the most effective at capturing small particles like bacteria, mold spores, and viruses. HEPA filters must meet government standards of removing at least 99.97% of particles 0.3 microns or larger. This makes them ideal for people with allergies or respiratory issues. However, HEPA filters also create the most resistance to airflow and need replacing every 6-12 months.
Activated Carbon Filters
Carbon filters use activated carbon to absorb odors and VOCs (volatile organic compounds). This makes them useful for removing smoke, fumes, and strong smells rather than capturing particles. Carbon filters are often combined with other filter media to provide well-rounded air cleaning. They need to be replaced about every 3-6 months.
Ionizing Filters
Ionizing filters, or electronic air cleaners, use an electrical charge to generate negative ions. These ions attach to particles, causing them to stick to oppositely charged collector plates in the filter. Ionizing filters can remove very small particles, but may produce trace amounts of ozone. They require cleaning the collection plates about once a year.
Locating Your Air Filter
Most homes have one main filter that needs to be replaced. Where you find this filter depends on your home's HVAC system.
Central Air Conditioners and Furnaces
For central air conditioner and furnace systems, the air filter is usually located along the return ductwork before the blower motor and heat exchanger. To access it, look for a removable panel or door on the side or bottom of your unit. Some filters slide out from the top or front. Refer to your owner's manual if you're unsure.
With central systems, the filter is often contained in a slot, rack, or filter grating. It may be held in place with screws or clamps. Make note of how your filter sits inside the system so you can properly replace it later.
Window Air Conditioners
Window air conditioning units have a filter behind the front grill. You'll need to open or remove this grill to get to the filter. Some grills are secured with screws or latches, while others can be pried open. Be gentle when handling the grill to avoid damaging the fins.
Once open, you should see a mesh filter that slides or lifts out. Some units have a disposable filter, while others have a reusable foam or mesh filter that can be vacuumed and rinsed. Check your manual to identify your filter type.
When to Change the Filter
Most HVAC experts recommend changing your air filter every 1-3 months. The ideal replacement frequency depends on several factors:
- Airflow and usage: Homes with high airflow or many hours of use need more frequent filter changes. Homes that run the HVAC system less may only need replacement every 3-6 months.
- Outdoor environment: Homes with high pollen, pollution, dust, etc benefit from changing filters monthly during allergy season or summer months. Areas with cleaner air can stretch changes to every 2-3 months.
- Pets or smoking: Homes with indoor pets or smoking will likely need monthly filter changes to reduce hair, dander, and odors in the air.
- Type of filter: Pleated filters often last 1-3 months while HEPA and other dense filters may only go 2-4 weeks before needing a swap.
Signs your air filter needs immediate changing:
- Reduced airflow from vents
- Dust around vents indicating air is leaking around a clogged filter
- Heating/cooling system running more frequently but not keeping up
- Visible dirt buildup on the filter
- Musty smells or odors blowing through vents
Don't wait until a filter looks dirty. The optimal time for replacement is when airflow starts to decline but before dust and particles sneak past the filter into your air ducts. Mark your calendar monthly or seasonally as a reminder to swap filters.
Materials Needed
Before changing your air filter, make sure you have everything you need. This typically includes:
- New compatible filter - Air filters come in different sizes and types. You'll want to get an appropriate replacement filter that matches the dimensions of your existing one. Check your owner's manual or look at your current filter to find the right specs.
- Gloves - Wearing gloves will protect your hands from dirt and debris as you handle the old filter. Any type of glove like cotton or nitrile gloves will work.
- Flashlight - A flashlight comes in handy to light up the often dark corners where the filter sits. You'll get a better view of the filter slot and any buildup around it.
You may also want to have a vacuum ready to clean out any dust or particles around the filter compartment. Avoid touching the filter itself as much as possible to limit kicking up dust.
Make sure you have all the necessary materials before starting the filter change process. This will make the job quicker and easier.
Turning Off the Air System
It is crucial to turn off your home's HVAC system before changing the air filter. This prevents any dust that has accumulated on the old filter from being blown into the air ducts and circulated through your home when you remove the old filter.
Locate the on/off switch for your HVAC system, which may be near your thermostat or on the side of your furnace unit. Set the switch to the off position so the blower and fan will not turn on. You may also need to turn off any ceiling fans or window A/C units to prevent them from pulling dust into the room while you change the filter.
If your thermostat runs on battery power, simply remove the batteries before changing the filter. This will ensure the system remains off.
With the HVAC system disabled, you can safely remove the old air filter without worrying about releasing built-up dust, allergens, and particles into your ductwork where they could then circulate back into your living spaces. Turning off the system is a simple but critical step in changing your air filter to keep your home's air as clean as possible.
Removing the Old Filter
Carefully pull the old air filter straight out of its slot to
avoid dislodging any dust or debris. Grip the filter firmly on all sides and slide it out slowly. Avoid tilting or shaking it, which could cause particles to fall off into the air system.
Once it's fully removed, inspect the old filter to see how much dirt and buildup it accumulated. This will give you an idea of how frequently you need to replace your air filters based on how much debris circulates through your home.
Be very careful not to drop any dust or particles from the old filter into the air system itself. Any debris that falls inside could get blown into your home's ductwork and contaminate your air supply. To prevent this, keep the old filter oriented upright as you remove it, and pull it away from the system quickly once it's out. You may want to have a plastic bag ready to immediately discard it.
With the old filter removed, inspect the now empty filter slot to ensure no debris got left behind. Use a small vacuum to suck up any dust or dirt around the opening before installing a fresh filter. Your air system is now ready for a clean new filter that will optimize your indoor air quality.
Inspecting the System
After removing the old air filter, take a moment to inspect the air system itself before installing a new filter. This is an opportune time to check for any issues since you have easy access to the internal components.
Look inside the system housing and use a flashlight to illuminate the interior. Check for any dirt buildup, dust, or debris that may have gotten past the filter. Some amount of dust is normal, but large accumulations of dirt indicate the past filter was not functioning optimally. Use a vacuum cleaner with a brush attachment to gently clean out any debris.
Also inspect the system housing, fan blades, vents, duct connections, and other components for damage. Look for cracks, loose parts, corrosion, or anything else that seems abnormal. The fan blades in particular should spin smoothly when moved. If any concerning issues are found, they should be repaired before installing the new filter.
A quick visual inspection ensures your system is clean and undamaged. Doing so allows the new filter to operate at peak performance. Preventative maintenance saves money in the long run by catching problems early before they worsen.
Installing the New Filter
When installing a new air filter, it's important to pay attention to the proper orientation. Air filters are usually rectangular or square shaped, with one side that has an arrow or other indicator pointing in the direction of the airflow. This side needs to face toward the blower motor or air handler unit.
Before sliding the new filter into place, take a quick look at the old filter to double check which way it was facing. You want the new one to sit in the exact same direction. Many filter slots or racks have guides or edges that help align the filter correctly.
Once you've oriented the new air filter properly, gently slide it into the filter slot or rack. Don't force it - it should slide smoothly into position. Push it all the way in until the filter sits flush within the slot. If it jams or catches, realign and try again. The filter frame should fit snugly within the filter rack or slot without any gaps or spaces on the sides.
With the new air filter fully seated in the proper orientation, you're ready to turn the air system back on and resume normal operation. Over time, dust and other particles will load up on the filter media. Check it periodically and replace when needed to keep your system running efficiently. Proper filter installation helps ensure clean indoor air quality.
Restarting the System
After installing the new air filter, you're ready to restart your home's air system. This process is simple:
- Turn the air system back on at the thermostat or control panel. Double check that the system is set to either heat or cool, depending on your needs.
- Go to several rooms and make sure you feel air flowing from the vents. Pay particular attention to rooms farthest from the air system to ensure airflow is strong throughout the home.
- Listen for any unusual sounds coming from the vents that might indicate an issue. The airflow should be smooth and consistent.
- Check the area around the air filter access panel for any leaks. Air should only be coming out of the vents.
Once you've confirmed normal airflow throughout the house, the air filter change process is complete! Changing your filters regularly will keep your system running efficiently and circulating clean air through your home.
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