Hydrogen gas buildup prevention in hot water heaters

Abstract

A hot water heater includes a controller, a hot water tank and a sensor operatively coupled to the hot water tank and the controller. The sensor is configured to detect use of hot water from the hot water tank. The controller is operative to determine an interval of non-use of hot water from the hot water tank; and enable a drain cycle to withdraw a portion of water from the hot water tank.

What is claimed is: 
     
         1 . A hot water heater comprising:
 a controller;   a hot water tank; and   a sensor operatively coupled to the hot water tank and the controller, the controller being operative in response to the sensor to detect use of hot water from the hot water tank to
 determine an interval of non-use of hot water from the hot water tank; and 
 enable a drain cycle to withdraw a portion of water from the hot water tank upon such determination. 
   
     
     
         2 . The hot water heater of  claim 1 , wherein the sensor comprises a water flow sensor and wherein the interval of non-use is determined if a time interval of no water flow from the hot water tank exceeds a predetermined time threshold. 
     
     
         3 . The hot water heater of  claim 1 , wherein the sensor comprises a water temperature sensor, wherein the interval of non-use is determined if any change in temperature of the water in the hot water tank during a pre-determined time interval does not exceed a pre-determined temperature change threshold value. 
     
     
         4 . The hot water heater of  claim 1 , further comprising a user interface operatively coupled to the controller, the user interface enabling a vacation mode of the hot water heater to be set, and wherein the controller is configured to detect the vacation mode of the hot water heater and enable the drain cycle to withdraw a portion of water from the hot water tank at predetermined time intervals. 
     
     
         5 . The hot water heater of  claim 4 , further comprising a wireless interface operatively coupling the user interface and the controller. 
     
     
         6 . The hot water heater of  claim 1 , further comprising a wireless radio connection between the controller and the sensor. 
     
     
         7 . The hot water heater of  claim 1 , further comprising an electrically operated hot water using appliance operatively coupled to the controller, wherein enabling the drain cycle comprises enabling operation of the electrically operated appliance to withdraw water from the water heater. 
     
     
         8 . A hot water heater system comprising:
 a hot water heater; and   a controller coupled to the hot water heater, the controller operative to:
 determine a stagnant state of the hot water heater; and 
 enable a drain cycle of the hot water heater. 
   
     
     
         9 . The hot water heater system of  claim 8 , wherein the drain cycle is enabled at predetermined time intervals during the stagnant state. 
     
     
         10 . The hot water heater system of  claim 8 , further comprising a water flow sensor operatively coupled between the controller and the hot water heater and wherein the controller is operative to:
 detect a flow of hot water from the hot water heater; and   determine an elapsed time from the detection of the detected flow; and   the stagnant state being indicated when the elapsed time is greater than the predetermined threshold time.   
     
     
         11 . The hot water heater system of  claim 8 , further comprising a water temperature sensor operatively coupled between the controller and the hot water heater and wherein the controller is operative to determine the stagnant state by monitoring a temperature of hot water in the hot water heater; and
 wherein the stagnant state being indicated when the temperature change does not exceed a predetermined temperature change threshold value during a time interval of predetermined duration.   
     
     
         12 . The hot water heater system of  claim 8 , further comprising:
 an appliance operatively coupled to the hot water heater and the controller;   wherein the controller is operative to enable the appliance to withdraw water from the hot water heater upon determination of a stagnant state.   
     
     
         13 . The hot water heater system of  claim 12 , wherein the appliance comprises a dishwasher, a washer, or an electronically controlled hot water discharge valve. 
     
     
         14 . The hot water heater system of  claim 8 , further comprising a user interface operatively coupled to the controller, the user interface enabling user selection of a vacation mode state of the hot water heater, wherein the controller is operative during the vacation mode to enable the drain cycle of the hot water heater at predetermined time intervals. 
     
     
         15 . The hot water heater system of  claim 14 , further comprising an electrically operated appliance with a control panel operatively coupled to the controller, the user interface comprising the control panel. 
     
     
         16 . The hot water heater system of  claim 14 , further comprising a wireless interface operatively coupling the user interface and controller. 
     
     
         17 . The hot water heater system of  claim 16 , wherein the user interface comprises a mobile communication device. 
     
     
         18 . The hot water heater system of  claim 8 , further comprising a home energy management system, the controller comprising a home energy manager of the home energy system. 
     
     
         19 . A hot water heater system comprising:
 a hot water heater;   an appliance coupled to the hot water heater and configured to withdraw hot water from the hot water heater; and   a home energy manager coupled to the hot water heater and the appliance, wherein the home energy manager is configured to enable the appliance to withdraw hot water from the hot water heater at predetermined time intervals.   
     
     
         20 . The hot water heater system of  claim 19 , wherein the home energy manager is configured to detect a stagnant state of the hot water heater and enable the appliance to withdraw hot water from the hot water heater upon detection of the stagnant state.