Air filters are designed with arrows printed on the sides to indicate the direction of air flow. These arrows should point away from the supply ducts and towards the fan. If the filter is on the wall, the arrow must be facing the wall. If your filter does not have an arrow, you should make sure that the side with the wire frame is facing outward.
This means that the side with the metal frame will be on the outside, or the side closest to you, and the side without it will be inside closer to the unit. It is important to note that air filters should always be installed in the direction of air flow. This means that when installing a new air filter in the return duct of an air conditioner, the arrows should point inward to indicate in which direction the air flows. On the other hand, when air is being pushed out, such as through a vent, then the arrows on the air filter should point outward.
When air filters become clogged with dust, dirt and debris, they can no longer do their job of improving indoor air quality. To ensure that your filter is working properly, invest in an electronic air filter monitor that tells you when it's time to change it. Additionally, it is important to disconnect the boiler power supply before changing your filter as dirt and dust can accumulate on internal parts of your air conditioning unit or oven. No matter what type of air conditioning system you have, each unit needs a quality filter that is properly adjusted to keep indoor air quality clean and your unit operating at peak efficiency. If your filter does not have an arrow indicating airflow direction, make sure that the wire mesh faces towards the fan of your HVAC system as this is the last surface that touches the air. Finally, if you have a multi-stage filter with a removable layer of fiberglass (velcro), an activated carbon honeycomb layer and a layer of pleated paper with a very thin layer of fiberglass, make sure that all layers are facing inwards towards your HVAC system.