A P-trap is a U-shaped pipe section installed in the condensate drain line of an air handler to prevent sewer gases or outdoor air from being pulled into the system. It uses a small amount of water to create a seal, ensuring that your indoor air quality remains high and odors are kept out of your living space. This is a vital component for multi-position air handler units installed in attics or closets. Without a proper trap, the suction from the blower fan can actually prevent the unit from draining, leading to water damage. You can find high-quality drainage parts on our site to complete your ducted or ductless installation. It is a small but essential piece of the puzzle when you shop all ducted solutions.