The arrow on your furnace filter indicates the direction of airflow through the filter. When installing a new furnace filter, it's essential to ensure the arrow is pointing towards the furnace or air handler. This means the arrow should be facing away from the return duct and towards the furnace's blower motor or the air handler's intake. Here's a step-by-step guide to installing your furnace filter correctly: Turn off your furnace or air handler: To ensure safety, turn off your furnace or air handler before replacing the filter. Set your thermostat to the "off" position and turn off the furnace switch, which is usually a standard wall switch located near your furnace. It might be mounted on the furnace itself or on a nearby wall. Locate the filter compartment: The filter compartment is usually found near the blower motor or air handler's intake, either in the furnace itself or in the return air duct. Remove the old filter: Carefully slide the old filter out of the compartment, being mindful of any dust or debris that may have accumulated on the filter. Check the arrow on the new filter: Look for the arrow on the frame of the new filter, which indicates the direction of airflow. Install the new filter: Align the arrow on the new filter with the direction of airflow. The arrow should be pointing towards the furnace or air handler (away from the return duct). Slide the new filter into the compartment, ensuring it sits securely. Turn the furnace or air handler back on: Turn the furnace switch back on and set your thermostat to the desired temperature setting and mode (heating or cooling) to restart the system. Replacing your furnace filter regularly, as recommended by the manufacturer or Martino HVAC, will help maintain optimal system performance and efficiency. If you're unsure about the correct installation of your furnace filter or need assistance, contact Martino HVAC, and our technicians will be happy to help.