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.

A heating apparatus comprising a heating chamber in which a heater is configured to heat a heating liquid, a heat exchanger configured to receive the heating liquid from the heating chamber and to transfer heat energy from the heating liquid to a separate heating fluid and a pressure regulator configured to control a pressure inside the heating chamber, wherein the regulator is coupled at a first side to a pressure in the heating chamber and at a second side to atmospheric pressure outside the apparatus. A method of heating is also described.

A multiple-piece vacuum-insulated heating tank for use in a water dispenser includes a threaded cover, a thermal insulation cover, and a heating tank body. The threaded cover is mounted on an upper opening of the heating tank body and includes a plastic cover and a protective cover mounted on and around the plastic cover. The thermal insulation cover is fitted in the upper opening and includes an upper cover and a lower cover. The lower cover is cup-shaped; is mounted with a heating tube, a water inlet pipe, a water outlet pipe, a thermowell, a temperature-sensing heat pipe, a heat collector block, and two snap-action thermostats at the bottom side; and has a sidewall formed with a step adjacent to the bottom side. The heating tank not only has a multiple-piece structure that facilitates mass production and maintenance, but also dispenses with electronic temperature control as is conventionally required.

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.

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.

The present disclosure relates to systems and methods for connecting to an auxiliary power source and operating a water heater. One exemplary aspect is directed to a water heater configured to heat a volume of water. The water heater can include a first heating system configured to operate at a first power and a second heating system configured to operate at a second power. The second power can be less than the first power. The water heater can further include a first AC connection configured to receive externally supplied AC power at a first voltage and a second AC connection configured to receive externally supplied AC power at a second voltage. The second voltage can be less than the first voltage. The water heater can use only the second heating system when the second AC connection receives the externally supplied AC power at the second voltage.

A recirculating bath includes a reservoir for receiving a working liquid, a recirculating pump, and at least one thermal element. The recirculating pump and thermal element are located externally to the reservoir so that the reservoir has an unobstructed working space. The thermal element may be thermally coupled to the working liquid through an interior surface of the reservoir, or the working liquid may be circulated over the thermal element by the recirculating pump in a chamber external to the reservoir. The recirculating bath may also include a lid that provides access to the reservoir by pivoting on a latching hinge. When open, the lid may provide a working surface adjacent to the reservoir. The lid may also include a selector that unlatches the hinge so that the lid can be removed. The recirculating pump may be fluidically coupled to the reservoir via a manifold.

A controller performs a first operation in which a heat source device directly or indirectly heats water in a first channel of a heat exchanger and a second operation in which the heat source device directly or indirectly cools the water in the first channel of the heat exchanger after the first operation ends.

A heat storage system includes a compressor that compresses refrigerant; a heat storage tank that stores a heating medium; heat exchange means provided outside the heat storage tank for heating the heating medium using heat of the refrigerant compressed by the compressor; a heat accumulating circuit including a feed path that feeds the heating medium flowing out of the heat storage tank to the heat exchange means, a return path that returns the heating medium heated by the heat exchange means into the heat storage tank, and a pump that circulates the heating medium; and control means capable of executing an initial operation that controls an operating frequency of the compressor at the beginning of a heat accumulating operation in which the heating medium heated by the heat exchange means is accumulated in the heat storage tank. The initial operation includes a first operation that maintains the operating frequency at a first frequency and, after the first operation, a second operation that maintains the operating frequency at a second frequency higher than the first frequency.