If you're looking at an oven filter, you'll want to check for the arrow that indicates the correct direction of airflow. This arrow should always be pointing towards the furnace and away from the return duct that carries air that needs to be heated or cooled. Most homeowners find that a MERV 7 or 8 pleated filter provides a good balance between cost and filtration efficiency. If you don't see an arrow, double-check the filter, as almost all of them have one. So, following this logic, if your house has two floors, with three ceiling filters on the lower level and two separate ceiling filters on the upper level, it's important to insert the air cleaner correctly.
If not, you won't be able to filter the air in your home efficiently, which can lead to a variety of maintenance issues. Fiberglass filters should be changed every 1-2 months and pleated paper filters should be changed every 3-5 months. In all types of furnaces, the filter is always located near the intake air blower fan and is positioned so that air flows through it. Some filters can even remove small particles like allergens, providing very healthy air for your living space. If you install the air cleaner incorrectly, your oven will have to work harder to do its job properly.
While inserting it in the wrong direction won't damage the system, it will reduce its efficiency and cost you more money. If your air cleaner doesn't have an airflow arrow, make sure that the wire mesh faces the blower of your HVAC system, as this is the last surface that touches the air. These filters trap 80-95% of particles 5 microns or larger, which is more than enough for most homes. To make sure you don't have to worry about which way to install the filter or which side of it goes up or down, just remember that the arrow should always point towards the oven heating compartment. When removing an old filter, try not to shake or hit it as this could release particles back into your home's air.
Metal is used as a support behind the filter media to maintain its rigidity as air passes through it.