Distribution and Abundance of Cylindrospermopsis raciborskii in Indiana Lakes and Reservoirs

This invention provides improved gas-fired heater means for supplying heat to a space, such as a room, house, building, vehicle, or the like. Basically, the improved gas-fired space heater means comprises: a first duct-like member having opposite front and rear ends and provided adjacent its front end with means for receiving, mixing and igniting a mixture of pressurized fuel gas and a combustion supporting gas within its interior that is discharged through exhaust conduit means from its rear end to an exhaust outlet located adjacent to its front end; a second duct-like member, surrounding the first duct-like member and the exhaust conduit means and having opposite forward and rearward ends, with the forward and rearward ends of the second duct-like member being respectively located adjacent to the front and rear ends of the first duct-like member and the second duct-like member having a fluid inlet opening located proximate to one of the opposite front and rear ends of the first duct-like member and a fluid outlet opening located between the opposite front and rear ends of the first duct-like member; and means for supplying a stream of pressurized fluid to the inlet opening of the second duct-like member for discharge through the outlet opening of the second duct-like member after having passed over the exteriors of and received heat from the first duct-like member and the exhaust conduit means to supply heated fluid to a space via second conduit means interconnectable between that space and the outlet opening of the second duct-like member.