Which way does the air filter go? If there is an arrow on the filter and you’re wondering which way it points, we’ve got the answer: which direction the airflow arrow should face.
- The air flow arrow on an air filter should always point in the direction the air flows, typically toward the furnace or return duct.
- Installing the filter with the arrow reversed restricts airflow, strains the system, increases energy costs, and risks damage or breakdown.
- Proper installation ensures effective dust capture, extends HVAC lifespan, improves indoor air quality, and prevents costly repairs.
- Choose the correct filter size and MERV rating; MERV 8 or 11 balance filtration and airflow for most homes.
- Replace and inspect your filter regularly, typically every 1-3 months, to maintain efficiency and keep air clean.
Which Direction Does The Air Flow Arrow on the Air Filter Go?
Simply put, the arrow should always point in the direction the air flows through the filter.
Here’s a video that explains it well:
Here’s an easy way to figure out how the airflow arrow should point. The arrow should ALWAYS point toward your return or furnace. When you install the filter, the pleated part should face you. The other side, which usually consists of a metal mesh or cardboard frame, should point towards the return.
The arrow should point toward the ceiling if your filter return duct is located there.
The airflow arrow should point toward your furnace if your filter is in your unit.
Why Do You Need a Furnace Filter?
Air filters are an essential part of your HVAC system. Without a filter installed, you risk damaging your furnace or HVAC unit and circulating allergens and other contaminants throughout your home’s air, which can cause chronic illnesses. You will also see an increase in energy costs because your system has to work harder to do its job.
Why is it important how you install your air filter? Does the airflow arrow matter?
There are many reasons why the direction you install your air filter matters.
How you install your air filter can impact the quality of your air and the longevity of your system.
Proper installation will allow it to do its job – effectively capture dust and other debris and prevent it from reaching the essential parts of your system.
If you’ve installed your filter incorrectly, buildup can occur on your system’s crucial components. This can also increase wear and tear, decrease its lifespan, and cause you to replace it much sooner than you would like.
What if I installed my air filter backwards?
A filter installed backwards will do more than let just a little extra dust slip by. It will restrict airflow, making your system work harder to keep your home comfortable. This will cause your energy bill to spike and unnecessarily strain the blower motor and other key components. Over time, this can lead to clogs, damage, or even a complete breakdown of your system.
An air filter installed correctly helps reduce energy costs because the system does not have to work harder to pull in air. Installing your HVAC filter correctly can help prevent costly system repairs and replacements, as well as high energy costs.
An air filter installed correctly also captures contaminants more effectively, improving your home’s indoor air quality.
Novice to Expert in No Time
We know that multiple scenarios could lead you to research this question. Maybe there is no filter to reference; it’s your first time installing an air filter, or you have a filter without an airflow arrow.
Check your HVAC owner’s manual if you’re unsure where your return is located.
Don’t sweat it! As long as you make sure the pleated part of the air filter faces you, you can confidently know you are installing your filter correctly.
You shouldn’t have to force the filter; it should fit snugly in the area where you insert it.
When in doubt, pay attention after you’ve installed your filter, and your system runs the air for the first time. Listen for unusual sounds coming from the furnace or air filter grille.
How to Choose the Right Filter Size and MERV Rating
Picking the correct filter size and MERV is as important as proper installation.
Filter sizes are usually printed on the side of the old filter or on the inside of the filter slot. Can’t find it? Check out our blog about how to measure your air filter.
How to Measure Your Air Filter
Once you know which size you need, you’ll want to ensure the MERV (Minimum Efficiency Reporting Value) rating is the best choice for you and your system.
For most homes, MERV 8 and MERV 11 work best. These MERVs will capture most dust, pollen, and pet dander without making your system work extra hard to pull in air. While jumping to a higher MERV rating might be tempting for its filtration capabilities, those filters can be too restrictive for residential systems and may reduce airflow, which isn’t good for your HVAC’s health.
If unsure, follow your system’s manual or ask a professional. Choosing the right size and MERV rating will help your AC filter do its job and keep your air and HVAC system happy.
Changing Your Air Filter Doesn’t Have to Be So Hard
Now that you know how to install your air filter, changing your HVAC filters should be easy home maintenance.
The most important thing you must remember is to replace your air filter regularly. The most common recommendation is to change every 1-3 months. Inspect your filter regularly to determine the best change cadence for you.
Why Should You Regularly Inspect Your Furnace Filter?
Even if you change your filter regularly, checking it every month or so is a good idea. Life moves fast, and pet hair, dust, and pollen can quickly build up on your filter.
Consistently checking your filter will help you catch any signs of visible damage, sagging, or buildup before it becomes a bigger issue.
A quick check can also help prevent airflow problems, keep your system efficient, and keep your air clean.
Going too long without replacing your filters can strain your equipment, raise your energy bill, and worsen air quality.
Need Replacement Air Filters?
The quality of your air filter is just as important as putting it in correctly. Poorly made filters will clog fast, making them just as ineffective and dangerous as if you had installed them incorrectly! If you’re unsure whether your current filter is sufficient, we’ve got you covered!
Filters Fast® Air Filters are an excellent choice for air conditioning filters. Each Filters Fast filter is made with high-quality pleated media to capture airborne contaminants in your home’s air.
Don’t wait! Keep continuous clean air in your home!
Do you wish there were an easier way to remember what size air filter you need and when it’s time to change it? Sign up for our Home Filter Club filter subscription service! Just find the filter you need, subscribe, and save!
We’re Here to Help
If you have any questions or need assistance installing your filter, contact us at [email protected]. A team member will be happy to help you ensure your filter is installed correctly.
For more information on air filters, check out the following articles:
- 4 SURPRISING Reasons Your Air Filters Get Dirty Quickly
- 5 Tips to Make Your Air Filter Change Smoother
- How to Save Money on a HVAC Repair
- Are Filters Fast® Air Filters Good Quality?
Brandon says
Hello Richard, thanks for reaching out to us. The air flow arrow should point towards the furnace. Hope this helps. If you have any questions, feel free to contact us at [email protected]. Take care!
Richard DeJohn says
I have 2 filters in my Centennial Oil furnace. Both go in at an angle with the pointed end facing towards the access door. The Chimney is at the top of the furnace entry door. I’m still not sure where the (air flow) arrows of the new filter are to point. Thank you
Brandon says
Hello Vicky, thanks for reaching out! The arrow on your air filter should point towards your furnace.
Vicky Helsel says
My air filter goes in the bottom of the furnace. Should the arrow point up or down? Thank you, vicky
Brandon says
Hello Ed, since you have a different design than our standard filters, we’ll need some more information to assist. If you could find your part number and contact our customer service team via e-mail, [email protected], they’ll be glad to help you further.
Ed says
I have a metal reusable filter. No arrow on filter? How do I know what side goes toward air flow? Thanks Ed
Brandon says
Hello Sheila, thanks for your comment. Usually the arrow is going to point toward the furnace, although the direction of the air flow can affect this. To be certain, we would need more detailed information about your furnace design. Please contact our customer care team at [email protected] for additional assistance in installing your filter.
sheila elliott says
Hi my filter vent is on the floor under the furance unit I take off the top door then the bottom. So which way should my arrow be facing. Right now I have the arrow facing up toward the unit. Thank you have a blessed day
Katie says
Michael,
Thank you for sharing that great tip!
Michael says
One way to check the air flow while your unit is running is to take a plastic bag (like you get at Walmart) and hold it up to the grill. If the bag is sucked in towards the grill, that’s the air flow direction.
Katie says
Hi Chelsea, great question! Unless the manufacturer of your filter says otherwise, the arrow should always point toward the furnace.
Chelsea says
My arrow points the opposite side the metal mesh is on so the metal should be on the furnace side not facing me?
Katie says
Cynthia,
Thank you for your feedback. The filter arrow should point toward your furnace system as it slides in.
Cynthia Tier says
None of this helped me. My air filter slides inside the furnace not on the outside of it. I still don’t know which way the filter arrow goes. Up or down. Nobody seems to know. I’m sure I’m not the only one with a furnace like this.
Katie says
Kristee,
We are so happy to hear that you found this blog post helpful! If you have any questions when it comes to air or water filtration we are happy to help!
Kristee Nassar says
Omg thanks! First time putting in an air filter. Newly single mom and just moved into an apartment. Didn’t ever have to worry about things like this because my husband always took care of em.
Katie says
Ken,
Thank you for reaching out to us. We asked our Air Filtration Expert to weigh-in on this and here’s what she recommended: Make sure you have a filter in each return. Perhaps start with a 1″ MERV 8 to see if that offers the improvement you are looking for. She also recommends adding room air purifiers to help improve the overall air quality.
Ken says
When I built my home 20 years ago my heat pump, duct..all were installed then. There were two return vents installed in the hallway that had 1” pleated filters in. 4 years ago I had to replace that heat pump with a new American Standard. That company installed me a 16x20x4 filter in the return just before the return to the handler. I use a Mer 13 and change it about every 8 months. The filter says a year. There is dust that gets in the hallway returns before reaching the filter near the handler meaning the return duct gets a lot of dust before ever getting to the filter. Can I put some kind of thin filter in the hallway returns to catch some of that house dust before it gets to the filter back before the handler? Could that be to much restriction? Any other options? Don’t like the idea of all that dust going into the hallway return bents before it travels 20 ft to the 20x16x4 filter before the return to handler?
Katie says
Andy,
You are absolutely right, I do live in the south and do not have a basement. I have also seen air filters installed next next to the furnace, but now you have my wheels turning as to what the differences are. This is really interesting!
Andy Murphy-Young says
I’ve never seen a place where you put the air filters in the wall intake like that. They have always been in the basement next to the furnace. Do you live in the south where their aren’t basements or use a different type of HVAC?