Every solid fuel stove loses a large amount of heat through the chimney and Flue. the HR-6 Miracle heat is designed to get a large portion of this heat back. The HR-6 in talls into a 12 in section of the stove pipe just above the stove. it has an integrated thermo disk that senses the heat in the chimney. Once hot, the quiet fan blows air through the heat exchanger and brings an extra 10% of the heat loss back into the room.