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About Damien

Damien McCusker, Manager of Arpi's residential service division, has been working in the HVAC industry for 18 years and has hands-on experience in new home installations, furnace and air conditioner replacements, sales and residential service. He spends most of his spare time sharing his passion for soccer with his kids and enjoys watching them at soccer practice and games.

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Furnace Filters: What Does the Arrow Mean?

Damien McCusker

If you’ve picked up a new furnace filter that has an arrow stamped on its side, it’s good to know that it’s there to help you put the filter in correctly. Filters make a big difference in HVAC systems because they keep much of the dirt and dust out of the air handler or furnace compartment.

Running a forced-air HVAC system with the wrong filter, a dirty filter, or none at all puts it on the fast track for high energy bills and premature part failure. Putting a filter in with the arrow going the wrong way also has negative ramifications, but it’s better than not using one at all or running it with a dirty filter.

How the Arrow Goes

The arrow points in the direction of the airflow. The point should go toward the inside of the furnace compartment. If the filter goes inside the ductwork, it should point toward the air handler or the furnace.

Filters Without Arrows

If you’re using a filter that doesn’t have an arrow but does have a mesh coating on one of its sides. The thinner or lighter side on unmarked filters always goes toward the air handler, furnace, or blower compartment. HVAC manufacturers want a free flow of air going into the air handler.

Why It Matters

Homes heat or cool faster with adequate airflow, which is why it’s so important to keep the furnace filter clean and placed in the right direction. When the airflow slows, it takes longer for your HVAC system to condition your home, driving up energy costs.

Understanding how to use your furnace filter will help you cut your energy costs and keep your HVAC system cleaner. For more information, contact Arpi’s Industries, providing HVAC services for Calgary-area homeowners.

Our goal is to help educate our customers in Calgary, Alberta about energy and home comfort issues (specific to HVAC systems). For more information about other HVAC topics, download our free Home Comfort Guide.

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