Water heating system and water heater

Abstract

A water heating system may include: a plurality of water heaters connected in parallel to each other; and a connection controller. The connection controller may be configured to: select one or more of the plurality of water heaters as active water heaters and a remainder of the plurality of water heaters as inactive water heaters; send an activation instruction to the controllers of the active water heaters; and send a stop instruction to the controllers of the inactive water heaters. The connection controller may be configured to: increase or decrease a number of the active water heaters based on a maximum flow rate of a valve and a detected flow rate in each of the active water heaters; and when increasing the number of the active water heaters, select a next active water heater from the inactive water heaters that have not sent an error signal.

What is claimed is: 
     
         1 . A water heating system comprising:
 a plurality of water heaters connected in parallel to each other; and   a connection controller configured to control the plurality of water heaters,   wherein each of the plurality of water heaters comprises:
 a heating unit configured to heat water; 
 a flow rate sensor configured to detect a flow rate of the water flowing into the water heater; 
 a valve configured to limit the flow rate of the water flowing into the water heater to a limit flow rate or lower; and 
 a controller configured to communicate with the connection controller, 
   wherein the controller is configured to:
 start heating the water with the heating unit when a detected flow rate detected by the flow rate sensor increases to an ignition flow rate while the heating unit is not heating the water; 
 adjust a heating capacity of the heating unit so that a temperature of the water heated by the heating unit approaches a hot water setting temperature while the heating unit is heating the water; and 
 stop heating the water with the heating unit when the detected flow rate falls to an extinguishing flow rate while the heating unit is heating the water, 
   wherein the connection controller is configured to:
 select one or more of the plurality of water heaters as active water heaters and a remainder of the plurality of water heaters as inactive water heaters; 
 send an activation instruction to the controllers of the active water heaters; and 
 send a stop instruction to the controllers of the inactive water heaters, 
   wherein each of the controllers is configured to:
 in a case of receiving the activation instruction from the connection controller, control the valve so that the limit flow rate becomes a maximum flow rate; 
 in a case of receiving the stop instruction from the connection controller, control the valve so that the limit flow rate matches zero; and 
 when an error related to the heating unit occurs, reduce the heating capacity of the heating unit by lowering the maximum flow rate, and send an error signal indicating an occurrence of the error to the connection controller, and 
   wherein the connection controller is configured to:
 increase or decrease a number of the active water heaters based on the maximum flow rate of the valve and the detected flow rate in each of the active water heaters; and 
 when increasing the number of the active water heaters, select a next active water heater from among one or more water heaters that have not sent an error signal among the inactive water heaters. 
   
     
     
         2 . The water heating system according to  claim 1 , wherein each of the plurality of water heaters further comprises a water temperature sensor configured to detect the temperature of the water flowing into the water heater, and
 wherein each of the controllers is configured to adjust the heating capacity of the heating unit based on the hot water setting temperature, the detected flow rate, and a detected temperature detected by the water temperature sensor.   
     
     
         3 . The water heating system according to  claim 1 , wherein each of the heating units comprises a gas burner. 
     
     
         4 . The water heating system according to  claim 1 , wherein the error related to the heating unit includes a temperature of a predetermined part of the water heater in which the heating unit is incorporated exceeding a threshold temperature, and
 wherein each of the controllers is configured to:
 when the error occurs, decrease the maximum flow rate in steps without sending the error signal to the connection controller; and 
 when the maximum flow rate falls to a threshold flow rate, send the error signal to the connection controller. 
   
     
     
         5 . The water heating system according to  claim 1 , wherein each of the plurality of water heaters comprises a first memory configured to store error information indicating that the error is occurring,
 each of the controllers is configured to continuously send the error signal to the connection controller while the error information is stored in the first memory, and   wherein the connection controller is configured to, when increasing the number of active water heaters, select a next active water heater from among one or more water heaters that have not sent the error signal in recent time period among the inactive water heaters.   
     
     
         6 . The water heating system according to  claim 5 , wherein each of the controllers is configured to, when the error is resolved, delete the error information stored in the first memory. 
     
     
         7 . The water heating system according to  claim 1 , wherein each of the controllers is configured to further send identification information for identifying the water heater together with the error signal to the connection controller,
 wherein the connection controller comprises a second memory configured to store the identification information received from the controller in association with error occurrence information indicating that the error is occurring in the water heater, and   wherein the connection controller is configured to, when increasing the number of active water heaters, select a next active water heater from among one or more water heaters of which identification information is not stored in the second memory in association with the error occurrence information among the inactive water heaters.   
     
     
         8 . The water heating system according to  claim 7 , wherein each of the controllers is configured to, when the error is resolved, further send an error resolving signal indicating that the error has been resolved together with the identification information to the connection controller, and
 wherein the connection controller is configured to, when receiving the error resolving signal and the identification information, delete at least one of the error occurrence information and the identification information stored in association with the error occurrence information in the second memory.   
     
     
         9 . The water heating system according to  claim 1 , wherein the connection controller is configured to, when receiving the error signal from at least one of the active water heaters, send the stop instruction to the at least one of the active water heaters and select a new active water heater from among the inactive water heaters. 
     
     
         10 . The water heating system according to  claim 1 , wherein the water heating system further comprises a notification unit configured to notify a user of the occurrence of the error. 
     
     
         11 . The water heating system according to  claim 1 , wherein the connection controller is configured to:
 determine one of multiple flow rate levels set in multiple stages for the detected flow rate in each of the active water heaters; and   increase or decrease the number of the active water heaters based on the respective numbers of the active water heaters of the respective determined flow rate levels.   
     
     
         12 . The water heating system according to  claim 1 , wherein the connection controller is composed of one or more of the controllers of the plurality of water heaters. 
     
     
         13 . A water heater, which constitutes one of a plurality of water heaters connected in parallel to each other, wherein the plurality of water heaters constitute a water heater set, the water heater comprising:
 a heating unit configured to heat water;   a flow rate sensor configured to detect a flow rate of the water flowing into the water heater;   a valve configured to limit the flow rate of the water flowing into the water heater to a limit flow rate or lower; and   a controller configured to communicate with one or more other water heaters of the water heater set,   wherein the controller is configured to selectively execute a primary process and a subordinate process subordinate to the primary process;   the subordinate process comprises:
 starting to heat the water with the heating unit when a detected flow rate detected by the flow rate sensor increases to an ignition flow rate while the heating unit is not heating the water; 
 adjusting a heating capacity of the heating unit so that a temperature of the water heated by the heating unit approaches a hot water setting temperature while the heating unit is heating the water; and 
 stopping to heat the water with the heating unit when the detected flow rate falls to an extinguishing flow rate while the heating unit is heating the water, 
   wherein the primary process comprises:
 selecting one or more of water heaters in the water heater set as active water heaters and a remainder of the plurality of water heaters in the water heater set as inactive water heaters; 
 sending an activation instruction to controllers of the active water heaters; and 
 sending a stop instruction to controllers of the inactive water heaters, 
   wherein the subordinate process comprises:
 controlling the valve so that the limit flow rate becomes a maximum flow rate in a case of receiving the activation instruction from a water heater executing the primary process; 
 controlling the valve so that the limit flow rate matches zero in a case of receiving the stop instruction from the water heater executing the primary process; and 
 when an error related to the heating unit occurs, reducing the heating capacity of the heating unit by lowering the maximum flow rate, and sending an error signal indicating an occurrence of the error to the water heater executing the primary process, and 
   wherein the primary process comprises:
 increasing or decreasing a number of the active water heaters based on the maximum flow rate of the valve and the detected flow rate in each of the active water heaters; and 
 when increasing the number of active water heaters, selecting a next active water heater from among one or more water heaters that have not sent an error signal among the inactive water heaters. 
   
     
     
         14 . The water heating system according to  claim 2 ,
 wherein each of the heating units comprises a gas burner,   wherein the error related to the heating unit includes a temperature of a predetermined part of the water heater in which the heating unit is incorporated exceeding a threshold temperature, and   wherein each of the controllers is configured to:
 when the error occurs, decrease the maximum flow rate in steps without sending the error signal to the connection controller; and 
 when the maximum flow rate falls to a threshold flow rate, send the error signal to the connection controller, 
   wherein each of the plurality of water heaters comprises a first memory configured to store error information indicating that the error is occurring,   each of the controllers is configured to continuously send the error signal to the connection controller while the error information is stored in the first memory, and   wherein the connection controller is configured to, when increasing the number of active water heaters, select a next active water heater from among one or more water heaters that have not sent the error signal in recent time period among the inactive water heaters,   wherein each of the controllers is configured to, when the error is resolved, delete the error information stored in the first memory,   wherein each of the controllers is configured to further send identification information for identifying the water heater together with the error signal to the connection controller,   wherein the connection controller comprises a second memory configured to store the identification information received from the controller in association with error occurrence information indicating that the error is occurring in the water heater, and   wherein the connection controller is configured to, when increasing the number of active water heaters, select a next active water heater from among one or more water heaters of which identification information is not stored in the second memory in association with the error occurrence information among the inactive water heaters,   wherein each of the controllers is configured to, when the error is resolved, further send an error resolving signal indicating that the error has been resolved together with the identification information to the connection controller, and   wherein the connection controller is configured to, when receiving the error resolving signal and the identification information, delete at least one of the error occurrence information and the identification information stored in association with the error occurrence information in the second memory,   wherein the connection controller is configured to, when receiving the error signal from at least one of the active water heaters, send the stop instruction to the at least one of the active water heaters and select a new active water heater from among the inactive water heaters,   wherein the water heating system further comprises a notification unit configured to notify a user of the occurrence of the error,   wherein the connection controller is configured to:   determine one of multiple flow rate levels set in multiple stages for the detected flow rate in each of the active water heaters; and   increase or decrease the number of the active water heaters based on the respective numbers of the active water heaters of the respective determined flow rate levels,   wherein the connection controller is composed of one or more of the controllers of the plurality of water heaters.