A liquid heating method and apparatus including a heat device 7 having a flow passage member forming a tubular flow passage for passing a sulfuric acid solution, a heater arranged on an outside of at least one of opposing flow passage surfaces of the tubular flow passage, a liquid draining line 10, an atmosphere opening line 12, valves 11 and 13, a liquid draining mechanism for draining the sulfuric acid solution heated at least in a heat receiving area between the opposing liquid flow passage surfaces of the tubular flow passage, a flow meter 6 for measuring a flow rate of the sulfuric acid solution, and a control unit 14 responsive to the flow meter 6 for determining a defective liquid flow in the tubular flow passage and for draining the sulfuric acid solution using the liquid draining mechanism.

A method and a device to heat water in an electrical boiler are disclosed. The method include the steps of storing user's requests of hot water in association with corresponding times of requests, heating water in advance to a next user's request, wherein the next user's request is estimated on the stored user's requests. The device is the hardware implementing the method.

An air-conditioning and hot water supplying composite system includes a heat source unit and a heat source-side heat exchanger, an indoor heat source unit, a hot water supply unit connected to the heat source unit and including a hot water supply-side heat exchanger and a hot water supply-side expansion device, and a controller that controls the heat source unit. The controller includes a mode switching unit that switches a control mode of the air-conditioning and hot water supplying composite system between a hot water supply control mode, a hot water supply preheating mode, and a condensing temperature control unit. The condensing temperature control unit determines the target condensing temperature according to a temperature of a heat medium subjected to heat exchange by the hot water supply unit, in the hot water supply control mode.

The present invention becomes possible to employ a main microprocessor with a relatively lower number of input ports, whereby while maintaining the performance and function of a water heater, the cost of a control apparatus is cut down. Some of sensors, adapted for measurement of various parameters which are for use in operational control of the water heater and in need of immediate response, are connected to a main microprocessor 31. The other sensors that are not in need of an immediate response, such as an ambient temperature sensor 36, are connected only to a sub microprocessor 32 if the main microprocessor 31 does not have any extra analog signal input port. The sub microprocessor converts an analog signal from the sensor 36 which is connected only to the sub microprocessor into digital data. And the sub microprocessor transmits the digital data to the main microprocessor through communication therewith.

Embodiments of the invention provide a pool heater including a housing, a first tankless heater, a second tankless heater, and a controller. The controller is configured to activate only the first tankless heater when a first condition is met, activate only the second tankless heater when a second condition is met, and activate the first and the second tankless heaters simultaneously when a third condition is met.

The present invention provides a hot water supply device. When a hot water supply operation is started in response to an instruction for checking a heat exchange state, a heat exchange state determiner 12 measures a post-boiling temperature Tup, which indicates the rise width of a temperature detected by a heat exchange outlet temperature sensor 26 from the point when the hot water supply operation stopped, and outputs a heat exchange success report if the post-boiling temperature Tup is lower than a first threshold temperature. Further, when the hot water supply operation is started independently of the instruction for checking a heat exchange state, the heat exchange state determiner 12 outputs a report of clogging of a heat exchanger if the post-boiling temperature Tup is higher than a second threshold temperature Bth, which is higher than the first threshold temperature Ath.

An electric water heater having a water holding tank defined by a cylindrical side wall, a top wall and a dome-shaped bottom wall. A cold water inlet is disposed for releasing water under pressure in a lower portion of the tank. Two or more resistive heating elements heat water in an upper and lower region of the tank. The lower portion of the cylindrical side wall and the outer circumferential portion of the dome-shape bottom wall form a circumferential cavitated area inside the tank in which sediments deposit forming a bed in which bacteria can proliferate. A conduit is secured about at least a substantial circumferential portion of an outer surface of the cylindrical side wall adjacent the cavitated area. A resistive heating wire is disposed in the conduit and has connection leads extending out of a free open end of the conduit to an access area to provide connection to power terminals and a control for controlling the supply of power to the resistive heating wire.

A furnace a smart furnace monitoring system, comprising: a) a wireless communication module; and b) a control module in communication with the wireless communication module, wherein the wireless communication module is capable of sending one or more status information messages to one or more recipients via a network.

The present disclosure relates to a method and a system for preventing freezing when a four-way valve in a heat pump water heater is failed, which includes following acts: In act S1, it is judged that whether current water temperature T is lower than a preset minimum temperature T.sub.min , for the water tank, if yes, perform act S2; if no, perform act S1 again. In act S2, it is judged that whether a cooling rate Td of the current water temperature T is greater than or equal to a preset rate ΔT; or, it is judged that whether the current water temperature T satisfies T<T.sub.min−a and whether T<T.sub.min−a stands for a first time period t1, in which a is a limit value of a temperature difference; if at least one yes, perform act S3, otherwise, return to act S1. In act S3, a heat pump system is controlled to stop and an electric auxiliary heating system is started. By judging whether a cooling rate Td of the current water temperature T is greater than or equal to a preset rate ΔT; or by judging whether the current water temperature T satisfies T<T.sub.min−a and whether T<T.sub.min−a stands for a first time period t1, it may be judged precisely that whether the four-way valve is failed, which avoids a misjudgment.

The autonomous energy saving device (2) enabling the control of a water heater (1) connected to a power grid comprising a phase P, a neutral N and a protective conductor T operating on a permanent power supply or during rate periods using a switch or timer, said energy saving device (2) comprises inputs E1, E2, E3 and the outputs S1, S2, S3 and between inputs E1 and E2 and the outputs S1 and S2 at least one primary circuit board (7) comprising at least one electronic component (3, 4) and a control algorithm to remove or reduce the heating times of the water heater (1) without changing the technical characteristics of the water heater, and in order to adapt its operation to the needs of the user.