Abstract: A heat generation and storage device supplements building heating and hot water systems. A roof cap including an air passage is connected to air outlets disposed within the roof structure of a building and to air passages formed by panels mounted over the surface of a building's roof. The roof cap is connected to a vent which either exhausts air to the atmosphere and/or recirculates air to a liquid heat storage tank. Heated air and heated water from the storage tank supplement a building's heating and hot water systems.