Water heating system with point-of-use control

Abstract

A water heater system includes an intermediate water heater having a storage tank in which water is initially received at an initial temperature. The intermediate water heater is controllable to heat the water to an intermediate temperature that is higher than the initial temperature. The water heater system also includes at least one point-of-use water heater coupled to the intermediate water heater for receiving the water from the intermediate water heater after the water has been heated to the intermediate temperature. The point-of-use heater is controllable to heat the received water to a point-of-use temperature, the point-of-use temperature being higher than the intermediate temperature.

1 . A water heater system comprising:
 an intermediate water heater including a storage tank in which water is initially received at an initial temperature, the intermediate water heater being controllable to heat the water to an intermediate temperature that is higher than the initial temperature; and   at least one point-of-use water heater coupled to the intermediate water heater for receiving the water from the intermediate water heater after the water has been heated to the intermediate temperature, the point-of-use heater being controllable to heat the received water to a point-of-use temperature, the point-of-use temperature being higher than the intermediate temperature.   
     
     
         2 . The water heater system of  claim 1 , wherein the intermediate temperature is a room temperature of approximately 75° Fahrenheit and the point-of-use temperature is a hot temperature of at least about 115 degrees Fahrenheit. 
     
     
         3 . The water heater system of  claim 1 , further comprising an uninsulated water pipe connected between the intermediate water heater and the at least one point-of-use water heater. 
     
     
         4 . The water heater system of  claim 1 , wherein each of the intermediate water heater and the point-of-use water heater include a 6 kilowatt heater. 
     
     
         5 . The water heater system of  claim 1 , wherein the point-of-use water heater is installed near a point-of-use device selected from at least one of a faucet and a shower head. 
     
     
         6 . The water heater system of  claim 1 , wherein the point-of-use water heater includes a pressure sensor for detecting when the point-of-use device is turned ON. 
     
     
         7 . The water heater system of  claim 1 , further comprising a programmable controller communicatively coupled to the intermediate water heater and the at least one point-of-use water heater, the programmable controller being operative to control the supply of electrical power to the intermediate water heater and the at least one point-of-use water heater. 
     
     
         8 . The water heater system of  claim 7 , wherein the programmable controller is operative to determine electrical power priority when two or more of the intermediate water heater and the at least one point-of-use water heater are ON simultaneously. 
     
     
         9 . The water heater system of  claim 8 , wherein the at least one point-of-use water heater is deemed to be a higher-priority heater than the intermediate water heater. 
     
     
         10 . The water heater system of  claim 8 , wherein the programmable controller determines electrical power priority after each one of one or more predetermined time intervals until at least one of the two more of the intermediate water heater and the at least one point-of-use water heater is OFF. 
     
     
         11 . A method for heating water in a water heater system, the method comprising:
 receiving water at an initial cold temperature in a storage tank of a central water heater;   heating the water in the storage tank to a warm temperature;   receiving the water from the storage tank at a point-of-use water heater; and   in response to detecting a water request at a point-of-use device, heating the water at the point-of-use water heater to a hot temperature.   
     
     
         12 . The method of  claim 11 , further comprising receiving the water from the storage tank at another point-of-use water heater. 
     
     
         13 . The method of  claim 11 , further comprising, in response to a priority controller detecting a water request, automatically receiving electrical power to one or more of the central water heater and the point-of-use water heater. 
     
     
         14 . The method of  claim 11 , further comprising prioritizing supply of electrical power to the central water heater and to the one or more point-of-use water heaters via a controller programmed to include a predictive algorithm, the predictive algorithm being a function of change in pressure, temperature, and time. 
     
     
         15 . The method of  claim 14 , wherein each of the central water heater and the one or more point-of-use water heaters are ranked from a higher priority heater to a lower priority heater, the higher priority heater receiving more electrical power than the lower priority heater. 
     
     
         16 . The method of  claim 15 , wherein the point-of-use water heater initially receives a first electrical power during an initial time period, the point-of-use water heater receiving a second electrical power during a subsequent time period, the first electrical power being greater than the second electrical power, the first electrical power being determined based on water pipe properties including at least one of water pipe length and water pipe mass. 
     
     
         17 . The method of  claim 14 , wherein the priority controller is operative to determine a current electrical power priority repeatedly after each of one or more predetermined time intervals. 
     
     
         18 . A water heater system comprising:
 a central water heater having an uninsulated storage tank in which water is initially received at a first temperature, the central water heater receiving electrical power to increase temperature of the water to a second temperature;   a plurality of point-of-use water heaters coupled to the central water heater via respective uninsulated water pipes for receiving the water from the central water heater, the plurality of point-of-use water heaters being adapted to increase the temperature of the water from the second temperature to a third temperature; and   a priority controller communicatively coupled to the central water heater and to the plurality of point-of-use water heaters, the priority controller being programmable to automatically send electrical power, as required, to the central water heater and point-of-use water heaters.   
     
     
         19 . The method of  claim 18 , wherein the priority controller is further programmable to include a predictive algorithm for determining priority when two or more of the central water heater and the plurality of point-of-use water heaters require electrical power. 
     
     
         20 . The method of  claim 19 , wherein, for any one of the point-of-use water heaters and the central water heater, the priority controller is further programmable to raise priority during a next time cycle if power was not received during an initial time cycle.