What Way Does a Furnace Filter Go In?

April 27 2017
furnace filter airflow direction

What Way Does a Furnace Filter Go In?

If you own a home that utilizes a forced-air furnace for heating/cooling/ventilating purposes, you might realize sooner or later that there’s a filter requiring a replacement. As time passes, your forced-air furnace may stop functioning optimally and display signs of increased electricity consumption and poor air quality. These are indications your furnace filter is getting clogged with dirt, debris and other harmful pollutants.

Fortunately, replacing a filter is a simple task. Many people experience trouble in the job, as they end up inserting the furnace filter backwards or in an improper position. This not only results in poor efficiency, but it may also result in the hot air getting blocked. Placing your furnace filter in backwards could affect your furnaces health and lead to permanent damage. Therefore, follow these steps to properly install a furnace filter:

Remove Old Filter & Determine Air Flow Direction

Determine the type of furnace you have, before you think of replacing it with a new one. Different furnaces use varied sizes of air filters. Therefore, start by turning off the furnace and removing the filter air box. You can find the air box next the furnace ducts, which begin near or at the top of the furnace. Air is usually pushed through these ducts to your entire home. In some furnaces, the air filter box is located adjacent to the furnace.

A small, wide-hinged door covers this box. You will be able to view the filter inside the notch that you slide it in to. Remove the existing filter and look for an arrow that indicates the direction of airflow. When removing the filter, make sure to use a permanent marker for drawing the airflow direction. This way, you’ll know exactly how to install the filter. At the same time, don’t forget to note the size of the air filter, which will be printed on the cardboard frame.

Select A Replacement Furnace Filter

Now that you have determined the direction of airflow and the size of the filter, it is time for you to get the right replacement. You can purchase new furnace filters from online shops, hardware stores, or home centers. The types can vary and be meant to last for a different time lengths. Before you select one, check the efficiency ratings of each furnace filter. This way, you can determine the effectiveness of your choice for removing smoke, dust, and pollen when air passes through it at low and high speeds.

For the best air quality, choose a filter that has a high Merv or APR rating. These filters provide superior air cleaning. You can also buy a custom size furnace filter if you need an unusual size.

Install New Furnace Filter

It’s time for you to install the new filter. Look for the appropriate markings that tell you which side of the filter should be facing the furnace. You should be seeing something like this “(16x25x4 Airflow→)”. Bear in mind the arrow must always face toward the furnace and away from the return duct. Be very careful when analyzing the markings, so that you don’t make a mistake during the installation. Then, slide the filter back into place and replace any cover that goes over it.

Now that you are familiar with the correct way a furnace filter should be installed, check our large selection of sizes and efficiencies to get the right filter for your home.

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