Patent ID: 7434544
Filing Date: 2008-10-14
Classification: F24H

Abstract:
1. A controller for controlling the operation of a fuel fired water heater appliance having a water storage vessel and a fuel fired heating apparatus located below the water storage vessel, the controller comprising: a first sensor disposed at an upper portion of the storage vessel for sensing the temperature of the water in an upper portion of the storage vessel; a second sensor disposed at a lower portion of the storage vessel for sensing the temperature of the water in a lower portion of the storage vessel; a surface mount sensor disposed on the outer surface of the storage vessel at the bottom of the vessel, for sensing the temperature of the bottom of the vessel, wherein the surface mount sensor is configured to provide output data associated with the temperature of the bottom of the vessel over time that signifies an undesirable level of sediment build-up; and a controller that monitors the rate of change of the temperature of the bottom of the vessel sensed by the surface mount sensor during a heating cycle, and discontinues operation of the water heater appliance upon detecting a rate of temperature increase of the bottom of the vessel that is indicative of an undesirable level of sediment build-up in the water storage vessel.