Chimney Sheep® Chimney Draught Excluder – Oblong 14″ x 36″ (36cm x 91cm)How does a Chimney Sheep draught excluder work? A chimney syphons air out of a building ALL THE TIME, not just when the fire is lit. 80 cubic metres of air flow up a chimney per hour. This removes all the lovely expensive centrally heated warm air from a room. The air needs to be replaced so it drags in cold air from around doors, windows, and other leaky parts of the building. This creates the cold air that we feel. If you plug the chimney, you will