Question: Please explain to me what a barometric damper does and why it is needed. Answer: A TEE section is inserted into the stove pipe. In the side of the TEE, a weighted flap is installed. Whenever the chimney suction is greater than the stove or furnace needs, the flap rotates open and lets room air into the chimney, thereby spoiling the draft. The benefit is that the stove or furnace will work more efficiently with a steady draft as opposed to constant changes in the chimney suction. For instance, a coal or wood stove may burn more steadily and for a longer period of time. An oil furnace will also be more efficient and less heat will be sucked up the flue when the unit is on AND off.