Systems and Methods for Instantaneous Hot Water Demand Startup

Abstract

Systems and methods are directed to water heater systems, including combi boilers and instantaneous water heaters, for initiating off-cycle purge operations, e.g., for energy reductions and efficiency means. Embodiments of the present invention can include at least one heat exchanger configured to heat water, at least one temperature sensor measuring water temperature at one or more locations within the heater system, and a control system in communication with the at least one heat exchanger. The control system can be configured to at least: determine an expected flow demand for hot water; monitor water temperature at an outlet of the at least one heat exchanger, initiate a burner sequence when the outlet temperature is greater than a delivery target temperature, and initiate a purge sequence when the when the outlet temperature is greater than a threshold temperature.

What is claimed is: 
     
         1 . A heater system configured to execute a purge sequence, the heater system comprising:
 at least one heat exchanger configured to heat water;   at least one temperature sensor measuring water temperature at one or more locations within the heater system; and   a control system configured to at least:
 determine an expected flow demand for hot water; 
 monitor water temperature at an outlet of at least one heat exchanger; 
 initiate a burner sequence when the outlet temperature has reached a delivery target temperature; and 
 initiate a purge sequence when the when the outlet temperature has reached a threshold temperature. 
   
     
     
         2 . The heater system of  claim 1 , wherein the purge sequence runs for a period of time until the delivery target temperature is reached. 
     
     
         3 . The heater system of  claim 1 , wherein the threshold temperature is equal to or greater than the target temperature. 
     
     
         4 . The heater system of  claim 1 , wherein when the outlet temperature is greater than the target temperature and less than a threshold temperature, the control system is configured to initiate a blower in preparation for initiating the burner sequence. 
     
     
         5 . The heater system of  claim 1 , wherein the threshold temperature is based on an anticipated demand of the hot water. 
     
     
         6 . The heater system of  claim 5 , wherein a decrease in anticipated demand decreases the threshold temperature. 
     
     
         7 . The heater system of  claim 1 , wherein the outlet is a domestic hot water outlet. 
     
     
         8 . The heater system of  claim 1 , wherein the at least one heat exchanger comprises:
 a first heat exchanger configured to heat water from the water tank; and   a second heat exchanger comprising a water inlet and water outlet configured to receive water from the first heat exchanger via a water inlet and deliver water to at least one of a domestic hot water outlet and the first heat exchanger.   
     
     
         9 . A method for executing a purge sequence, the method comprising:
 determining an expected flow demand for hot water;   heating water using at least one heat exchanger in response to a request for hot water;   monitoring water temperature at an outlet of at least one heat exchanger;   initiating burner sequence when the outlet temperature has reached a delivery target temperature; and   initiating a purge sequence when the when the outlet temperature has reached a threshold temperature.   
     
     
         10 . The method of  claim 9 , wherein the purge sequence runs for a period of time until the delivery target temperature is reached. 
     
     
         11 . The method of  claim 9 , wherein the threshold temperature is equal to or greater than the target temperature. 
     
     
         12 . The method of  claim 9 , wherein when the outlet temperature is greater than the target temperature and less than a threshold temperature, the control system is configured to initiate a blower in preparation for initiating the burner sequence. 
     
     
         13 . The method of  claim 9 , wherein the threshold temperature is based on an anticipated demand of the hot water. 
     
     
         14 . The method of  claim 13 , wherein a decrease in anticipated demand decreases the threshold temperature. 
     
     
         15 . The method of  claim 9 , wherein the outlet is a domestic hot water outlet.