Using your K&N 20 x 24 x 1 HVAC filter is easy. First, install it in your HVAC system according to the system's instructions. The filter should fit snugly in its designated place. As you use it, it will trap dust and other contaminants. Check the filter regularly, about once a month. When you notice it's dirty, remove it from the system. To clean it, gently wash it with mild soap and water. Rinse thoroughly to get rid of all the soap. Let it dry completely before reinstalling it. Avoid using harsh chemicals or scrubbing too hard as this could damage the filter. With proper care, your K&N filter will keep providing clean air for a long time.