Abstract: A commercial water heater apparatus, including a housing, a radial-fired burner within the housing, a single continuous, multiple loop, finned coil tubing heat exchanger for circulating water around the burner, having at least a first set of inner coils forming a coil trough therebetween and a second set of outer coils nested within the coil trough formed by the inner set of coils, the outer set of coils forming a second coil trough around the exterior thereof, and a coil baffle interposed in the second exterior trough for deflecting heat adjacent to the second set of coils.

Abstract: A scale agitator for tank type liquid heaters employs a flexible non-cathodic tube through which liquid can flow. The liquid can be obtained from the tank or the supply of makeup liquid to be heated can be used. The tube may be fastened to a clean-out cover mounted to the exterior of the tank so that the tube can be inserted into and removed from the tank through the opening behind the clean-out cover.