A safe water heater comprises a housing assembly, a box assembly, and a water inlet and outlet assembly. The housing assembly comprises a first housing with a mounting cavity. The box assembly comprises a water tank with a water-containing cavity. The water inlet and outlet assembly comprises a water inlet subassembly and a water outlet subassembly. The water inlet subassembly comprises a second water inlet pipe communicating with the water-containing cavity, a first water inlet pipe able to communicate with outside, and a leak-proof mechanism. The leak-proof mechanism is capable of sealing a water inlet of the second water inlet pipe.

A water heating system is provided. The water heating system includes a tank having a wall, a water inlet defined through the wall and configured to allow ingress of water into the tank, and a water outlet defined through the wall and configured to allow egress of water from the tank. The water heating system also includes a first heating element disposed in a first portion of the tank. The first heating element has a substantially elongate shape and is inclined at a first predefined angle with respect to a base of the tank.

A boiler includes a tank, a gas circuit that includes a main combustion chamber in the tank and branch tubes in the tank that extend off of the main combustion chamber, and a water circuit fluidly isolated from the gas circuit. The water circuit includes a first manifold and water tubes that extend off of the first manifold. Each water tube extends through a respective one of the branch tubes, which may serve to preheat the water prior to discharge of the water into the tank.

An electrical heater device comprises an heating element, which includes two electrodes and a heating body made of a polymer-based material having a PTC effect, in contact with the electrodes. Each electrode comprises a meshed structure, which extends in a length direction and in a width direction, and is embedded at least partially in the heating body. Each electrode further comprises an electrical-distribution element which is fixed to the meshed structure and includes a distribution portion that extends in the length direction, or in the width direction, or in both the length and width directions of the meshed structure.

A safe water heater comprises a housing assembly, a box assembly, and a water inlet and outlet assembly. The housing assembly comprises a first housing with a mounting cavity. The box assembly comprises a water tank with a water-containing cavity. The water inlet and outlet assembly comprises a water inlet subassembly and a water outlet subassembly. The water inlet subassembly comprises a second water inlet pipe communicating with the water-containing cavity, a first water inlet pipe able to communicate with outside, and a leak-proof mechanism. The leak-proof mechanism is capable of sealing a water inlet of the second water inlet pipe.

A water heater includes a tank defining an interior volume having an inlet and an outlet, a heating element configured to heat water within the tank, and a bypass in fluid communication between the inlet and outlet and configured to divert at least a portion of the supply water from the inlet to the outlet.

A tank-style residential and light commercial hot water heater is provided. The tank-style residential and light commercial hot water heater can include a tank, an intake nipple for receiving a liquid into the tank, an outflow nipple for dispensing the liquid from the tank after heating, and a dedicated return nipple having a valve. The dedicated return nipple is configured to couple to a hot water recirculating system, and the valve is configured to open when the dedicated return nipple is coupled to the hot water recirculating system to allow the dedicated return nipple to receive a recirculated form of the liquid dispensed from the outflow nipple back into the tank. When not in use with a hot water recirculating system, the valve may be closed.

An oil boiler includes an outer container having openings at opposite ends, a combustion chamber that covers an opening at an upper end of the outer container and in which a combustion reaction occurs, a lower cover that covers an opening at a lower end of the outer container, a plurality of flue tubes to heat heating water flowing in the outer container by guiding combustion gas, a burner including a fuel nozzle that sprays fuel, an air nozzle that injects air, and a spark plug that ignites a mixture of the fuel and the air, and a flame tube part that defines a tube space by surrounding a partial space in which the mixture is ignited, the flame tube part including a flame tube having an open lower end and a recirculation hole formed through the flame tube such that the combustion gas is introduced into the flame tube.

A water holding tank for electric water heaters is described and particularly an improvement to the bottom end construction of the tank to prevent bacteria proliferation and the elimination of the cavitated circumferential area where sediments deposit to form a culture bed for bacteria to proliferate. Instead of modifying the shape of the bottom wall the improvement is a simple solution in that a filler material is set in at least a lowermost portion, and preferably a major portion, of the cavitated circumferential area to isolate that area from the interior of the water holding tank and form smooth flat surface areas which are planar to cause sediments to disperse and not form beds for bacteria to proliferate.

The invention provides a condensing boiler 100 including a heat exchanger 160, the heat exchanger including at least one fluid flow cassette 162a, 162b, 163a, 163b, 164a, 164b, each cassette comprising first 181 and second 182 sheets, wherein at least the first sheet has corrugations 185, 186, 187 along a length of the sheet so as to form a number of grooves extending across a width of the sheet, wherein the second sheet is attached against the first sheet so as to enclose the grooves to form a number of fluid flow passageways 193 extending across a width of the cassette in between the first and second sheets, and wherein the cassette is substantially curved across its width such that the fluid flow passageways are substantially curved along their length. The invention also provides a method of manufacturing a heat exchanger or condensing boiler.