A controller of a heat pump water heating system drives circulation pumps, and uses a heat pump unit to increase a temperature of tank water within a hot water storage tank via a plate heat exchanger if the temperature of the tank water detected from a temperature sensor is lower than a heat source switch tank temperature, and the controller stops one of the circulation pump, drives other circulation pumps, and uses a boiler to increase the temperature of the tank water within the hot water storage tank via the plate heat exchanger in a shorter time than that of a case in which the heat pump unit is used to increase the temperature if the temperature of the tank water detected from the temperature sensor is equal to or higher than the heat source switch tank temperature.

A controller for a tankless water heater is programmed to perform a descaling procedure that includes: closing a bypass valve to prevent fluid from bypassing a heat exchanger of the tankless water heater; activating a pump to cause a descaling solution to circulate through the tankless water heater; monitoring a flow rate of the descaling solution; and deactivating the pump responsive to one of: i) an amount of time that the pump is active exceeding a time limit, ii) the flow rate exceeding a first threshold, or iii) a change in the flow rate exceeding a second threshold.

An automatically flushing water heater maintenance system may be provided, the system including a water heater and a water heater controller. The water heater may include an inlet, an outlet, and a flush outlet having a first control valve in flow communication therewith. The first control valve may be configured to control a flow of water and sediment through the flush outlet out of the water heater. The water heater controller may be configured to communicate with the first control valve by transmitting a first control signal to the first control valve, the first control signal configured to cause the first control valve to open or close as part of an automatic flushing process. As a result of the flushing, the useful life of the water heater may be extended, and/or water heater leakage alleviated. Insurance discounts may be provided based upon using the automatic water heater flushing functionality.

An automatically flushing water heater maintenance system may be provided, the system including a water heater and a water heater controller. The water heater may include an inlet, an outlet, and a flush outlet having a first control valve in flow communication therewith. The first control valve may be configured to control a flow of water and sediment through the flush outlet out of the water heater. The water heater controller may be configured to communicate with the first control valve by transmitting a first control signal to the first control valve, the first control signal configured to cause the first control valve to open or close as part of an automatic flushing process. As a result of the flushing, the useful life of the water heater may be extended, and/or water heater leakage alleviated. Insurance discounts may be provided based upon using the automatic water heater flushing functionality.

A hot water supply device 1 includes a fin-and-tube type heat exchanger (21) that applies heat to fresh water with combustion gases, and a heat exchanger casing (22) for housing the heat exchanger (21), and in order to be able reliably to determine by a simple method whether the hot water supply device is clogged by lime scale, there are provided a temperature detector (31) for detecting the surface temperature of the heat exchanger casing (22) and a control unit (7) that determines that scale has built up in the heat exchange tubing (27) of the heat exchanger (21) when the temperature detected by this temperature detector (31) is greater than a set temperature.

A control unit includes a scale detection unit for detecting, while the a burner provides combustion, occurrence of clogging with scale in a tube of a heat exchanger, and an output unit for outputting a result of a detection by the scale detection unit, a storage stores information including a numerical value representing how many times a surface temperature of the heat exchanger measured by a temperature measuring unit exceeds at least one of a plurality of threshold values. While the burner provides combustion when the surface temperature measured by the temperature measuring unit exceeds at least one of the plurality of threshold values the scale detection unit adds a predetermined value to the numerical value in the storage and when the numerical value attains a defined value or more the scale detection unit detects occurrence of clogging with scale.

A water heating apparatus includes: a water heating circuit; a heater for heating the water heating circuit; and a controller for controlling the water heating apparatus. The water heating circuit includes a heat exchanger for heating a fluid including water and hot water, and a pipe for supplying the fluid via the heat exchanger. The controller is configured to drive the heater in a cleaning mode in which a cleaning liquid for cleaning an inside of the heat exchanger is supplied to the heat exchanger through the pipe.

Example methods, apparatus and articles of manufacture to detect impurities in flow-through water heaters are disclosed. An example apparatus includes a flow-through water heater having a conduit to conduct a fluid flowing therethrough, a heating element extending around at least a portion of the conduit, and first and second temperature measuring elements to determine respective first and second temperatures at different locations on the conduit; and a computing unit to at least detect an impurity deposit in the conduit based on a difference between the first and second temperatures.

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.

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.