Answer:
Thank you for your question on the model MD6TU make up air damper. The MD6TU is designed to be used with six inch duct work and a wall cap that would accept six inch duct work. It is not normally recommended to be installed with a roof cap because the vent always needs to be clear of any obstructions such as snow. Most roof caps are six to seven inches tall and can be covered very easily with snow during the winter months.