Patent ID: 7804047
Filing Date: 2010-09-28
Classification: F23M,F24H,H01L,H02J,H02M

Abstract:
1. In a water heater having a first sensor, a second sensor, and a logic unit, wherein each of the first and second sensors are operable to provide an output indicative of water temperature, and wherein the logic unit uses the output indicative of water temperature to control heat cycling of the water heating device, a method for performing a sensor-matching test comprising: the logic unit performing a test on at least one of the first and second sensors so as to produce a test output; the logic unit determining whether the test output satisfies at least one predetermined threshold, wherein the at least one predetermined threshold is indicative of a properly-functioning sensor; and the logic unit setting a fault condition indicative of a non-properly-functioning sensor when the test output does not satisfy the at least one predetermined threshold, wherein the step of performing the test on the at least one of the first and second sensors so as to produce a test output comprises: (a) performing a heat cycle; (b) using the first and second sensors to detect respective first and second water temperatures after the heat cycle completes; (c) determining a first differential between the first and second water temperatures; (d) using the first and second sensors to detect respective third and fourth water temperatures after the water heater has been idle for a predetermined period of time; and (e) determining a second differential between the third and fourth water temperatures; and wherein the step of determining whether the test output satisfies the at least one predetermined threshold comprises determining whether the first differential is greater than a first differential threshold and whether the first differential minus the second differential is greater than a second differential threshold, and wherein the step of setting the fault condition indicative of the non-properly-functioning sensor comprises setting the fault condition if the first differential is not greater than the first differential threshold.