Ben shows us how he built a mock up of a Heat Reclamation Chimney. The idea is to capture some of the heat that exits through the chimney. When you have a look at a hot water tank or furnace that is basically what those devices are doing. Normally there is a heat source at the bottom and exits from the top, the rising heat passes through pipes that are filled with water to extract the heat. Ben has a much simpler system, he is using an increased exterior surface area brick. There is then an air space created around the chimney where a variable amount of air can be pulled out of into the room. There are some other people experimenting with this concept like Stasys Blazonis with his Chimney Heat Exchanger Project. Another area that is gaining in popularity is waste water heat recovery.