Disclosed herein is a water heating system including a water heater having a tank, and a first temperature sensor disposed toward a top end of the tank to measure a first temperature and a second temperature sensor disposed toward a bottom end of the tank to measure a second temperature. The water heating system can further include a controller communicably coupled to the first temperature sensor and the second temperature sensor, where the controller determines an amount of heated water in the tank based on one or more algorithms and measurements made by the first and second temperature sensors.

Disclosed herein is a water heating system including a water heater having a tank, and a first temperature sensor disposed toward a top end of the tank to measure a first temperature and a second temperature sensor disposed toward a bottom end of the tank to measure a second temperature. The water heating system can further include a controller communicably coupled to the first temperature sensor and the second temperature sensor, where the controller determines an amount of heated water in the tank based on one or more algorithms and measurements made by the first and second temperature sensors.

Disclosed herein is a water heating system including a water heater having a tank, and a first temperature sensor disposed toward a top end of the tank to measure a first temperature and a second temperature sensor disposed toward a bottom end of the tank to measure a second temperature. The water heating system can further include a controller communicably coupled to the first temperature sensor and the second temperature sensor, where the controller determines an amount of heated water in the tank based on one or more algorithms and measurements made by the first and second temperature sensors.

An example indirect water heater is disclosed having a water storage tank with a primary heat exchanger. A heating fluid inlet of the primary heat exchanger receives a heating fluid from an external heat source into the primary heat exchanger. A heating fluid outlet of the primary heat exchanger returns the heating fluid to the external heat source after traveling through the primary heat exchanger. A secondary heat exchanger has a water source inlet and a water source outlet. The secondary heat exchanger is provided in thermal connection with the primary heater exchanger to preheat a source water before discharging the source water from the water source outlet into the water storage tank.

A hot water supply apparatus includes a heat exchanger that heats water for hot water supply, a pressure controller provided in a subsequent stage of the heat exchanger, and a trap that promotes deposition of scale. The pressure controller pressurizes the water for hot water supply. The trap is provided in a subsequent stage of the pressure controller.

The present disclosure provides a water storage tank and a gas water heater. The water storage tank includes: a tank body provided with an interface at one end; an adapter provided with a water inlet connector, a water outlet connector, and a waste discharge connector; and a connection pipe installed in the tank body, one end of the connection pipe communicating with the water outlet connector, another end of the connection pipe being spaced apart from an end of the tank body away from the interface.

An energy cutoff apparatus for a water heating system includes a safety cutoff circuit and a presence detection circuit. The safety cutoff circuit receives a temperature signal from a temperature sensor. The temperature signal is indicative of whether a temperature of water in the water heating system within a permissible temperature range. The safety cutoff circuit disables a safe operation current branch when the temperature signal indicates the water temperature is outside the permissible water temperature range. The presence detection circuit detects a presence of the temperature sensor and disables a presence detection current branch if the temperature sensor is absent. Switches can power heating elements of the water heating system responsive to the safe operation current branch being enabled and the temperature sensor being present and can disable the heat elements responsive to the safe operation current branch being disabled or the temperature sensor being absent.

Disclosed herein is a water heating system including a water heater having a tank, and a first temperature sensor disposed toward a top end of the tank to measure a first temperature and a second temperature sensor disposed toward a bottom end of the tank to measure a second temperature. The water heating system can further include a controller communicably coupled to the first temperature sensor and the second temperature sensor, where the controller determines an amount of heated water in the tank based on one or more algorithms and measurements made by the first and second temperature sensors.

Disclosed are a water heating device, and a method for manufacturing a smoke tube for a water heating device. The water heating device includes a body having an interior space that accommodates water, a combustion chamber provided in the interior space of the body and that provides a space for a combustion reaction, a smoke tube connected to the combustion chamber, that guides a combustion gas generated during the combustion reaction from the combustion chamber to an outside of the body, and wound in a spiral shape in at least a partial section, and a turbulator provided in at least a partial section of an interior of the smoke tube to make the combustion gas flowing in the interior of the smoke tube turbulent, and wound in a spiral shape to correspond to the spiral shape of the smoke tube.

A method for controlling a system including a heat pump, a space heater, space cooler, a thermal battery, an electrical battery and a grid access system, including: turning on at least one of the heat pump, charging of the thermal battery, discharging of the thermal battery, charging of the electric battery and discharging of the electric battery if a hot water demand exists; turning on at least one of the water heater, charging of the thermal battery, discharging of the thermal battery, charging of the electric battery and discharging of the electric battery if a space heating demand exists; turning on at least one of the water heater, charging of the thermal battery, charging of the electric battery and discharging of the electric battery if a space cooling demand exists; and backfeeding electricity from the electric battery to a grid through the grid access system if electricity sale is desired.