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.

A hot-water storage type boiler having a vortex guide portion is proposed. Since the present invention includes a spiral portion inside a casing, water supplied into the casing is moved to the upper side of the space part, while being in contact with fire tubes for a long time by moving spirally along the spiral portion, thereby improving heat exchange efficiency of the fire tubes. In addition, since the water supplied into the casing is moved spirally along the spiral portion to form a vortex, the flow of water moving in the direction of a hot-water discharge portion collides with a firebox lower surface part at a high speed, thereby having an effect of preventing scale from accumulating on the firebox lower surface part.

The exhaust duct includes an exhaust collecting portion connected a heat exchanger and an exhaust guiding portion communicating with the exhaust collecting portion and extended upward in a state close to a side of a cylindrical body of the heat exchanger. The exhaust collecting portion includes a connection opening constituting an inner peripheral wall, into which a cylindrical outlet side connection portion at the lower end of the heat exchanger is fitted, and a groove provided on an outer peripheral side than the inner peripheral wall of the connection opening. The packing includes a seal portion sandwiched in a compressed state between the inner peripheral wall of the connection opening in the exhaust collecting portion and an outer peripheral wall of the cylindrical outlet side connection portion in the heat exchanger to constitute a seal and an anchor portion inserted into the groove of the exhaust collecting portion.

A laser based water heating element formed from at least two components, e.g., a shaft and a laser beam generator, wherein the shaft and laser beam generator of the laser based water heating element are axially aligned, i.e., the shaft is centered on the laser beam generator, where the laser beam generator is a self-contained green, infrared and red-line laser module with an integrated laser driver circuit, optics and laser diode such that, in operation, the laser beam generator generates a laser beam with an output power that is sufficient to cause the shaft to generate radiant heat and thereby cause the temperature of water within a water heater to rise.

An electrically heated vessel having a heating element that is replaceable without draining the vessel includes a tank, which has an orifice positioned therein, and a housing. The housing is tubular and has a first terminus, which is closed, and a second terminus, which is open. The second terminus is coupled to the tank with the housing extending from the orifice into the tank. The housing has a plurality of first apertures positioned therein. A tube, which has a plurality of second apertures positioned therein, is positioned in and rotationally engaged to the housing. The tube has a first end, which is closed, and a second end, which is open and selectively couplable to an electric heating element that is inserted thereinto. Each second aperture is selectively alignable with an associated first aperture so that the electric heating element can heat a fluid positioned in the tank.

A water heater includes a water tank and a flow-through heating element. The water tank contains heated water. The flow-through heating element is located in the lower portion of the water tank and heats water as water is passed through an interior channel of the heating element. In another configuration, the water heater further includes a recirculation line and the heating element further includes an input end external of the water tank to receive water to be heated and an output end to output heated water into the water tank. The recirculation line transports water from the water tank to the input end of the heating element that is external of the water tank.

A thermal energy storage (TES) component includes a shell having first and second ports, and at least a first set of thermally conductive sealed containers that contain a TES media for storing thermal energy. A first set of sealed tubes containing a first TES media are in a first section of the shell, and a second set of sealed tubes containing a different TES media are in a second section of the shell. Electric heating elements are immersed in at least some of the tubes, and may extend only from one end of the tube. In some embodiments more than one heating element is immersed in the TES media and positioned to enhance convective flow. In some embodiments electric heating elements are disposed externally on the sealed tubes. Some tubes are tapered or frustoconical, with heating elements provided in a larger-diameter portion of the tubes.

A fluid heating system for heating a production fluid using a thermal transfer fluid, the production fluid being contained in a vessel includes an electric blower configured to receive ambient air and electrical input power and to provide output source air, a combustion system configured to receive the source air from the electric blower and to receive fuel and to provide the thermal transfer fluid, a heat exchanger configured to receive the thermal transfer fluid from the combustion system and configured to be in thermal communication with the production fluid to provide convective heat exchange from the thermal transfer fluid to the production fluid, and to provide output exhaust gas, and wherein the electric fan provides a predetermined volume flow rate of the output source air at a predetermined blower efficiency such that the fluid heating system has a Bulk Heat Flux of at least about 14.7 kBTU/Hr/ft.sup.2 and a Pressure Drop of at least about 0.7 psi.

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.

A PTC liquid heating device comprises a housing extending along a longitudinal axis and defining a liquid inlet and a liquid outlet. A PTC heating unit is inserted into the housing and extends along the longitudinal axis. The PTC heating unit includes a sleeve, a heat conductor and at least one PTC heating core. The heat conductor has a pair of metal profiles defining at least one chamber, the at least one chamber extending along the longitudinal axis to receive the at least one PTC heating core. The heat conductor is located in the sleeve and has a shape matching the sleeve. The PTC liquid heating device provides uniform and efficient heat transfer. In addition, the PTC liquid heating device has improved corrosion resistance and insulation properties, thereby prolonging the service life of the PTC liquid heating device.