Wood burning swimming pool heater

A swimming pool heater that heats a private swimming pool and can be used to provide heating for a house, a cottage or a commercial swimming pool. Wood, that is often found around pools, is used as primary fuel. This oven has a cylindrical external appearance and is disposed horizontally. It is made of an interior wall and an exterior wall in between which water circulates. The interior wall plays the role of fire chamber and heat exchanger; the section having the shape of an annular zig-zag offers more surface for heat exchange than a simple cylinder thus increasing the overall heater efficiency. The left-over ashes insulate the bottom of the heating chamber replacing often used tiles. For general use, logs and branches are used as fuel, and an increase of 20 to 30 degrees F. of the water of a typical garden pool is attained overnight.