A combination water heating, air conditioning refrigerant system is described. The combined system includes a plurality of independently adjustable electronic expansion valves. The expansion valves can independently modulate the delivery of high-temperature, high-pressure refrigerant to either a water heat exchanger or an outside condenser. A controller can receive input signals, including temperature signals from one or more temperature sensors that indicate the temperature at various locations of the system. The temperature signals include one or more of water temperature signals, ambient air temperature signals, or refrigerant super heat temperatures signals. In response to the input signals, the controller can output control signals to one or more of the plurality of electronic expansion valves.

A tooling and method for flexible through connection of a double-liner water heater. The tooling includes a transition shaft, a tooling connecting plate and a fastening screw. The method includes: allowing a shaft head of the transition shaft to be in fit with an inner surface of an outer flange of a lower liner for welding; allowing an end hole to be in fit with an outer surface of an inner flange of an upper liner for welding; after welding seams are cooled, removing the tooling, and enameling the upper and liners; forming through-flexible connection between the inner and outer flanges; and firmly fitting the upper and lower liners together with two steel strips to ensure that a gap between the upper and lower liners is not greater than 7 mm.

A tooling and method for flexible through connection of a double-liner water heater. The tooling includes a transition shaft, a tooling connecting plate and a fastening screw. The method includes: allowing a shaft head of the transition shaft to be in fit with an inner surface of an outer flange of a lower liner for welding; allowing an end hole to be in fit with an outer surface of an inner flange of an upper liner for welding; after welding seams are cooled, removing the tooling, and enameling the upper and liners; forming through-flexible connection between the inner and outer flanges; and firmly fitting the upper and lower liners together with two steel strips to ensure that a gap between the upper and lower liners is not greater than 7 mm.

A heating apparatus is disclosed. The heating apparatus comprises a PTC heating element, a first electrode, a second electrode, a first protection layer, a second protection layer, a first interlayer, and a second interlayer. A hardness of the first protection layer is greater than that of the first interlayer. A hardness of the second protection layer is greater than that of the second interlayer.

A water heating device includes: a heat exchanger having a case to which heating air is supplied, and heat transfer pipes accommodated inside the case; and a straightening vane arranged on the downstream side in a heating air flow direction of the heat transfer pipes, and having a plurality of vent holes. The heat transfer pipe includes a plurality of pipe body portions that extend along a direction intersecting the heating air flow direction and approach the straightening vane. The plurality of vent holes are arranged so as to overlap the plurality of pipe body portions in the heating air flow direction.

A heat exchanger unit according to the present invention comprises: a sensible heat exchanger including a sensible heat exchange pipe disposed in a sensible heat exchange area for heating water used for heating by receiving sensible heat generated by a combustion reaction, wherein the sensible heat exchange pipe receives the water used for heating and flows same through the interior, and a sensible heat fin disposed in the sensible heat exchange area, wherein the sensible heat fin is formed in a plate shape across the sensible heat exchange pipe and penetrated by the sensible heat exchange pipe; and a latent heat exchanger positioned downstream from the sensible heat exchange area on the basis of a reference direction, which is a flow direction of combustion gas generated during the combustion reaction, the latent heat exchanger including a latent heat exchange pipe disposed in a latent heat exchange area.

A heat exchanger unit according to the present invention comprises: a sensible heat exchanger including a sensible heat exchange pipe disposed in a sensible heat exchange area for heating water used for heating by receiving sensible heat generated by a combustion reaction, wherein the sensible heat exchange pipe receives the water used for heating and flows same through the interior, and a sensible heat fin disposed in the sensible heat exchange area, wherein the sensible heat fin is formed in a plate shape across the sensible heat exchange pipe and penetrated by the sensible heat exchange pipe; and a latent heat exchanger positioned downstream from the sensible heat exchange area on the basis of a reference direction, which is a flow direction of combustion gas generated during the combustion reaction, the latent heat exchanger including a latent heat exchange pipe disposed in a latent heat exchange area.

A heat exchanger unit according to the present invention comprises: a sensible heat exchanger including a sensible heat exchange pipe disposed in a sensible heat exchange area for heating water used for heating by receiving sensible heat generated by a combustion reaction, wherein the sensible heat exchange pipe receives the water used for heating and flows same through the interior, and a sensible heat fin disposed in the sensible heat exchange area, wherein the sensible heat fin is formed in a plate shape across the sensible heat exchange pipe and penetrated by the sensible heat exchange pipe; and a latent heat exchanger positioned downstream from the sensible heat exchange area on the basis of a reference direction, which is a flow direction of combustion gas generated during the combustion reaction, the latent heat exchanger including a latent heat exchange pipe disposed in a latent heat exchange area.

An enclosure for a water heating system for a service selected from the group consisting of receiving water through a water inlet port, recirculating water through a recirculation port, outputting a heated water supply through a water outlet port, receiving a gas supply through a gas inlet port, receiving an air supply through an air inlet port and a combustion exhaust through an exhaust port, the enclosure including a wall through which at least one of the water inlet port, the recirculation port, the water outlet port, the gas inlet port, the air inlet port and the exhaust port is disposed, the wall is configured to be removable for access to equipment disposed inside the enclosure, the equipment is connected to the at least one of the water inlet port, the recirculation port, the water outlet port, the gas inlet port, the air inlet port and the exhaust port.

An exhaust duct includes an upper duct being open at opposite ends thereof and a lower duct being open at a tip end thereof. One end of the upper duct is connected, inside an enclosure of a water-heating device, to an exhaust adaptor disposed on the enclosure, and an opposite end of the upper duct communicates with the tip end of the lower duct. The upper duct is connected to the lower duct so as to be slidable along a reference direction in which the lower duct extends from the tip end of the lower duct, and the upper duct is configured to be separated from the exhaust adaptor by sliding along the reference direction.