Q: Jason, We have a coal-burning fireplace that we will never use. The chimney has a smoke shelf and (as far as I can tell) no damper. The chimney measures 14 X 16 just above the smoke shelf. I guess that means we will need to order a custom Chimney Balloon. How much would that cost and how do we go about doing it? – ST

A: ST, Just to be on the safe side I would go with a 15”X18” custom Chimney Balloon.

FYI, If your smoke shelf is far up your chimney you can also measure the space below the smoke shelf and before the damper if that allows enough space for the Chimney Balloon. The most important thing is to look for the most convenient space to reach. If the best location is higher than 12 inches past where you can touch with your hand, consider purchasing an HEK Extender with your Chimney Balloon. – Jason