Scale deposit detection in water heater appliances

Abstract

A water heater appliance includes a heat exchanger, a first temperature sensor disposed on a front surface of the heat exchanger, a second temperature sensor disposed on an elbow extending from the heat exchanger, and a controller. A method of operating the water heater appliance includes monitoring a first temperature of the front surface of the heat exchanger with the first temperature sensor while the water heater appliance is running, monitoring a second temperature of the elbow with the second temperature sensor when the water heater appliance stops running, calculating a difference between the first temperature and the second temperature, and determining scale buildup in the heat exchanger based on the difference between the first temperature and the second temperature.

What is claimed is: 
     
         1 . A method of operating a water heater appliance, the water heater appliance comprising a heat exchanger, a first temperature sensor disposed on a front surface of the heat exchanger, a second temperature sensor disposed on an elbow extending from the heat exchanger, and a controller, the method comprising:
 monitoring a first temperature of the front surface of the heat exchanger with the first temperature sensor while the water heater appliance is running;   monitoring a second temperature of the elbow with the second temperature sensor when the water heater appliance stops running;   calculating a difference between the first temperature and the second temperature; and   determining scale buildup in the heat exchanger based on the difference between the first temperature and the second temperature.   
     
     
         2 . The method of  claim 1 , further comprising, before an initial installation of the water heater, conducting a reliability test. 
     
     
         3 . The method of  claim 2 , further comprising recording an initial first temperature of the front surface of the heat exchanger while the water heater appliance is running during the reliability test and an initial second temperature of the elbow after ending the reliability test and the water heater appliance stops running. 
     
     
         4 . The method of  claim 3 , further comprising, when the first temperature of the front surface of the heat exchanger exceeds the initial first temperature during operation of the water heater appliance, updating the initial second temperature to the second temperature. 
     
     
         5 . The method of  claim 3 , further comprising, when the second temperature of the elbow exceeds the initial second temperature after the water heater appliance stops running, updating the initial first temperature to the first temperature. 
     
     
         6 . The method of  claim 1 , further comprising activating a scale detection mode of the water heater appliance, wherein the scale detection mode comprises the steps of monitoring, calculating and determining, and wherein the steps of monitoring, calculating and determining are performed in response to activating the scale detection mode. 
     
     
         7 . The method of  claim 6 , further comprising receiving a command via a user input, wherein activating the scale detection mode occurs in response to receiving the command via the user input. 
     
     
         8 . The method of  claim 1 , further comprising detecting a type of water flowing through a water line. 
     
     
         9 . The method of  claim 8 , wherein detecting the type of water comprises detecting one of hard water or softened water. 
     
     
         10 . The method of  claim 8 , wherein detecting the type of water flowing through the water line includes receiving a user input, the user input comprising the type of water. 
     
     
         11 . A water heater appliance comprising:
 a heat exchanger a first temperature sensor disposed on a front surface of the heat exchanger;   a second temperature sensor disposed on an elbow extending from the heat exchanger; and   a controller, the controller configured to:
 monitor a first temperature of the front surface of the heat exchanger with the first temperature sensor while the water heater appliance is running; 
 monitor a second temperature of the elbow with the second temperature sensor when the water heater appliance stops running; 
 calculate a difference between the first temperature and the second temperature; and 
 determine scale buildup in the heat exchanger based on the difference between the first temperature and the second temperature. 
   
     
     
         12 . The water heater appliance of  claim 11 , wherein the controller is further configured to, before an initial installation of the water heater, conduct a reliability test. 
     
     
         13 . The water heater appliance of  claim 12 , wherein the controller is further configured to record an initial first temperature of the front surface of the heat exchanger while the water heater appliance is running during the reliability test and an initial second temperature of the elbow after ending the reliability test and the water heater appliance stops running. 
     
     
         14 . The water heater appliance of  claim 13 , wherein the controller is further configured to, when the first temperature of the front surface of the heat exchanger exceeds the initial first temperature during operation of the water heater appliance, updating the initial second temperature to the second temperature. 
     
     
         15 . The water heater appliance of  claim 13 , wherein the controller is further configured to, when the second temperature of the elbow exceeds the initial second temperature after the water heater appliance stops running, updating the initial first temperature to the first temperature. 
     
     
         16 . The water heater appliance of  claim 11 , further comprising activating a scale detection mode of the water heater appliance, wherein the scale detection mode comprises the steps of monitoring, calculating and determining, and wherein the steps of monitoring, calculating and determining are performed in response to activating the scale detection mode. 
     
     
         17 . The water heater appliance of  claim 16 , further comprising receiving a command via a user input, wherein activating the scale detection mode occurs in response to receiving the command via the user input. 
     
     
         18 . The water heater appliance of  claim 11 , further comprising detecting a type of water flowing through a water line. 
     
     
         19 . The water heater appliance of  claim 18 , wherein detecting the type of water comprises detecting one of hard water or softened water. 
     
     
         20 . The water heater appliance of  claim 18 , wherein detecting the type of water flowing through the water line includes receiving a user input, the user input comprising the type of water.