Patent ID: 8069013

Claim:
For use with a water heater in which heated water is stored for on-demand delivery therefrom, the water heater having a predetermined heated water setpoint temperature T max and a predetermined minimum water temperature T min , monitor/diagnostic apparatus comprising: a monitoring portion operable to detect the temperature T meas of the stored water and responsively generate an output signal indicative of its magnitude; and a diagnostic portion operable to: (1) determine successive time periods, during heating of the stored water from T min to T max , required to respectively heat the stored water from each of a series of progressively lower temperatures to the next higher temperature in said series thereof, and then (2) utilize said output signal, and the total magnitude(s) of an associated one or more of the determined successive time periods, to generate a diagnostic signal indicating to a user an estimated time for the water heater to recover from T meas to T max .