Abstract: A direct contact water heating system employs a vertical water tower having a sidewall with a combustion inlet opening spaced above the tower lower end. A generally horizontal combustion chamber has a sidewall in communication with the tower combustion inlet and an end wall spaced from the water tower. A burner has a combustion outlet in communication with an opening in the end wall, the combustion chamber end wall having an annular area surrounding the burner combustion outlet. Products of combustion flow from the burner, through the combustion chamber into the water tower through the combustion inlet opening. A shell has an inner end attached to the water tower sidewall. A sidewall portion of the shell surrounds the combustion chamber sidewall and an annular portion is spaced exteriorly of the annular area of the combustion chamber end wall. An interior surface of the outer shell and an exterior surface of the combustion chamber form a closed envelope having a water inlet and a water outlet.

Abstract: A hot water heating system having a water tower with a cold water inlet at the upper end and a hot water outlet at the lower end has a large diameter combustion inlet opening in the sidewall. A combustion chamber is secured to the water tower at the combustion inlet so that products of combustion of fuel consumed in the combustion chamber pass into the water tower and are exhausted through a vent. An outer shell surrounds the combustion chamber providing an annular chamber having a water inlet. A port communicates the upper interior of the annular chamber with the interior of the water tower. Water is circulated from a hot water storage through the annular chamber and through the port into the interior of the water tower. The recirculated water thus accomplishing the dual functions of cooling the combustion chamber and salvaging heat extracted from the combustion chamber to augment the heat of the water in the storage tank.