Systems and methods are provided for an air purifier with over pressurization relief, including the following components. A room air inlet is configured to fluidly receive air from a room. A supply duct inlet is configured to fluidly receive air from a forced air system. An air filter and or air purification means is configured to filter/purify air. An outlet is configured to expel filtered/treated air into the room. A bypass damper system has at least one air filtering mode position and a bypass mode position. A pressure control mechanism is configured to automatically allow the bypass damper system to move from at least one air filtering mode position to a bypass mode position when the air received from the supply duct inlet exceeds a bypass threshold. The bypass mode position guides air from the supply duct inlet into the room without requiring passage through the filter and the outlet.