The Right Direction: Knowing Which Way Your Furnace Filter Goes In

Changing Furnace filters and impact on air quality in Amesbury, MA

A furnace is pivotal in maintaining a home’s warmth and comfort during chilly months. Yet, one component that often gets overlooked in this system is the furnace filter. As with many things in life, direction matters, and this couldn’t be truer when it comes to positioning a furnace filter. For homeowners and potential customers, understanding the importance of which way a furnace filter goes can significantly affect furnace efficiency and indoor air quality. NextGen Aire has created this guide to help.

The Importance of Furnace Filters

Before diving into the specifics of orientation, it’s crucial to comprehend the role of a furnace filter. A furnace filter is a critical component that traps and removes airborne particles like dust, pollen, and pet dander before they circulate through the HVAC system. This helps maintain a healthier indoor environment and ensures that the furnace operates efficiently. When particles accumulate in a system, they can clog internal components, causing the furnace to work harder than necessary, leading to increased energy consumption and wear.

Recognizing the Right Direction

So, which way does a furnace filter go in? One side features a stiff wire mesh on most furnace filters, while the other may be softer or more fibrous. The wire mesh side always faces the furnace, supporting the softer filtration side, which faces the incoming air.

Often, filters come with arrows or markings indicating the direction of airflow. It’s essential to align these arrows with the direction in which air flows through the system. Incorrect placement can hamper the filter’s performance and damage the furnace over time.

Changing Filters: A Regular Ritual

The frequency of changing a furnace filter varies based on several factors:

  • Type of Filter: Basic fiberglass filters should be replaced every 30 days, while more advanced pleated filters can last up to 90 days. There are even some high-efficiency filters that can function effectively for six months to a year.

  • Living Conditions: Homes with pets, smokers, or residents with allergies may require more frequent filter changes. Additionally, increased dust and contaminants can mean changing the filter regularly if the home is located in a high-pollution area or undergoing renovation.

  • Usage: If the furnace is in continuous use, it’s a given that the filter will trap more particles and thus need more frequent replacement.


Regularly inspecting the furnace filter and noticing the buildup will help homeowners decide when to change.

Changing the Filter: A Step-by-Step Guide

  1. Safety First: Before starting, turn off the furnace.

  2. Access the Filter: Locate and open the furnace’s access panel.

  3. Remove the Old Filter: Slide out the old filter. Note the direction of the airflow arrows.

  4. Insert the New Filter: Using the arrows as a guide, slide in the new filter, ensuring it’s facing correctly.

  5. Secure and Restart: Replace the access panel and turn on the furnace.

Direction Makes a Difference

Knowing the right direction for a furnace filter and ensuring timely replacements can significantly affect a home’s air quality and furnace efficiency. For homeowners and potential customers, it’s a small step that brings peace of mind and considerable benefits.

For further inquiries or assistance regarding furnace maintenance or any HVAC concerns, don’t hesitate to contact NextGen Aire. The team is committed to providing expertise and ensuring every home is warm, comfortable, and safe.

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