What should be done to unused openings in chimneys and vents?

Unused openings in chimneys and vents should be closed to prevent the entry of pests, debris, and moisture, which can compromise the integrity of the chimney or vent system. Closing these openings helps to maintain the efficiency of the venting system and ensures that it functions properly if it needs to be used in the future. Additionally, sealing off unused openings can help to prevent downdrafts that could allow harmful gases to enter living spaces. Proper closure methods may include using masonry or appropriate caps, ensuring that the closure is durable and weather-resistant to prevent any future issues. This approach is critical for ensuring safety and maintaining the structural conditions of the chimney and vent systems.