Method for Monitoring the Energy Content of a Water Storage Tank System

Abstract

A method of controlling a heat up of a domestic hot water tank, whereby tank temperatures are measured. The tank temperatures are fed into a control unit and a heating device is activated to heat up water in the tank when the control unit calls for heat. The method comprises a step of feeding an incoming cold-water temperature value into the control unit and generating a parameter effected by this incoming cold-water temperature. The tank temperature is measured and is related to the thermal energy content of the tank, whereby the tank temperature is measured with an integral water temperature sensor mounted to the tank, further effecting the parameter. It processes then a call for heat depending on a comparison of a set point value with the parameter generated from the tank temperature and the measured cold-water temperature.

1 . A method of controlling a heat up of a hot water tank having a control unit, the method comprising:
 measuring a tank temperature;   feeding the tank temperature into a control unit;   activating a heating device to heat up water in the tank when the control unit calls for heat;   feeding an incoming cold-water temperature value into the control unit;   generating a parameter effected by the incoming cold-water temperature;   measuring the tank temperature which is related to the thermal energy content of the tank, where the tank temperature is measured with a sensor mounted to the tank;   modifying the generated parameter based on the tank temperature;   processing a call for heat depending on a comparison of a set point value with the modified parameter.   
     
     
         2 . The method according to  claim 1 , further comprising:
 calculating an exact value of thermal energy content as a function of reference mass and the modified parameter.   
     
     
         3 . The method according to  claim 2 ,further comprising:
 calling for heat when the exact value is less than the set point value.   
     
     
         4 . The method according to  claim 1 ;
 wherein the tank temperature is measured with an integral temperature sensor.   
     
     
         5 . The method according to  claim 2 , further comprising:
 activating the heating device depending on the amount of the calculated exact value.   
     
     
         6 . The method according to  claim 5 ;
 wherein the heating element is activated when the amount of the calculated exact value is less than a specified value of thermal energy content.   
     
     
         7 . The method according to  claim 1 , further comprising:
 calculating the exact value of thermal energy content by multiplying the reference mass parameter by a temperature rise value.   
     
     
         8 . The method according to  claim 7 ;
 wherein the temperature rise is the difference between the set point temperature and the incoming cold-water temperature.   
     
     
         9 . The method according to  claim 1 , further comprising:
 comparing a measured actual cold-water temperature signal with a previous stored cold-water temperature;   updating the stored cold-water temperature value if the measured actual cold-water temperature signal is different from the previous stored cold-water temperature; and   utilizing the updated stored cold-water temperature value to calculate the parameter.   
     
     
         10 . The method according to  claim 9 ;
 wherein the stored cold-water temperature value is updated when the actual cold-water temperature signal is lower than the previous stored cold-water temperature.   
     
     
         11 . The method according to  claim 9 ;
 wherein the stored cold-water temperature value is updated if the actual cold-water temperature signal is different from a defined value.   
     
     
         12 . The method according to  claim 1 , further comprising:
 identifying a tapping event to detect a true cold-water temperature in an adequate duration after a tapping begin.   
     
     
         13 . The method according to  claim 12 , further comprising:
 detecting the cold-water temperature in an adequate duration, which adequate duration begins after the end of an inadequate duration.   
     
     
         14 . The method according to  claim 13 , further comprising:
 determining the inadequate duration when a time frame is exceeded.   
     
     
         15 . The method according to  claim 14 ;
 wherein the time frame is approximately 20 seconds.   
     
     
         16 . The method according to  claim 13 ;
 wherein the adequate duration starts with the end of the inadequate duration and ends after more than 30 seconds or at or after the end of the tapping event.   
     
     
         17 . The method according to  claim 13 , further comprising:
 comparing successive cold-water temperature measurements with differences using the temperature information of sensors and a time base.   
     
     
         18 . The method according to  claim 17 , further comprising:
 detecting the tapping begin if a difference of two successive cold-water temperature values is more than 2 K of the time base.   
     
     
         19 . The method according to  claim 18 , further comprising:
 starting a first timer with an inadequate duration.   
     
     
         20 . The method according to  claim 19 , further comprising:
 comparing an actual cold-water temperature with a previous one to calculate a difference and, if the difference is less than a special parameter, activating a second timer to measure the actual cold-water temperature information of a sensor during a time base.   
     
     
         21 . The method according to  claim 20 , further comprising:
 after the second timer is started to detect the incoming cold-water temperature frequently for a minimum duration of more than 10 seconds, putting each single resulting cold-water temperature value in a register, and comparing the successive measured values; and   determining that the measurement is valid if a difference of less than a second parameter exists.   
     
     
         22 . The method according to  claim 21 , further comprising:
 averaging the cold-water temperature values in the register,   comparing an actual averaged cold-water temperature with the former stored averaged value; and   if the difference of the actual calculated value compared to the former stored value is more than 2 K, updating the former stored value using a simple moving averaging process.   
     
     
         23 . The method according to  claim 1 , further comprising:
 identifying a tapping event with an adequate duration in order to detect the real cold-water temperature by comparison of previous cold-water temperature values with the measured actual cold-water temperature signal;   storing a lowest value of cold-water temperature of the previous cold-water temperature values and the measured actual cold-water temperature signal; and   utilizing the stored lowest value to calculate the exact value of thermal energy.   
     
     
         24 . The method according to the  claim 23 , comprising the step in which
 the energy needs of at least one tank  1  are provided to an energy supplier or sent to a utility.   
     
     
         25 . The method according to  claim 1 , further comprising:
 a utility company sorting consumers into different energy demand classes in order to stabilize a voltage, a frequency, or both, of an electric grid.   
     
     
         26 . The method according to  claim 24 ;
 wherein the heating unit is configured to be remotely controlled by the utility company.   
     
     
         27 . The method according to  claim 1 ;
 wherein the sensor mounted outside the tank.   
     
     
         28 . The method according to  claim 1 ;
 wherein the sensor mounted inside the tank.