Method for forming an in-line water heater having a spirally configured heat exchanger

摘要

A method for forming an in-line heater for heating water supplied to a hot water carpet cleaning extractor includes the formation of a spiral flange upon the exterior surface of an elongated cylindrical body having a bore therein to define a heat exchanger. The flanged heat exchanger is inserted into a cylindrical housing having an inner diameter smaller than the outer diameter of the spirally flanged heat exchanger by heating the housing to increase the inner diameter thereof sufficiently to allow the spirally flanged heat exchanger to be be received therein. Upon cooling, the housing shrinks into watertight engagement with the spiral flange to define a spiral water floe conduit between the ends of the in-line heater. The first and second ends of the heat exchanger are then welded to the housing. Quick disconnect fittings are threaded into the in-line heater to establish communication with the end of the spiral water conduit. The in-line heater is heated by a removable electric resistance heating element inserted into the bore of the heat exchanger body and controlled by a control thermostat and a overheat cutoff switch.