Abstract: A water heater capable of utilizing as one of its heat sources hot exhaust gases emitted from at least one other heat source such as a furnace fueled by a natural resource fuel such as gas or oil, and capable of utilizing as another of its heat sources heat emitted from a fluid heated by solar energy. The water heater comprises a central flue having a heat conductive wall, one end of the said flue having a thimble member secureable to an exhaust pipe carrying hot exhaust gases from a heat source fueled by a natural resource fuel, and the other end of said flue secureable to a chimney leading to the atmosphere. Disposed within the flue is a turbulator means which disperses entering hot exhaust gases along the surface of the flue wall.