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.

An air handling unit (AHU) for a heating, ventilation, air conditioning, and refrigeration (HVACR) system includes a housing and a combustion heater disposed within the housing. The housing includes a combustion section with a first channel and a second channel. The combustion heater includes heat exchanger tubes and a tube support that supports heat exchanger tubes within the combustion section. The tube support slidably disposed in the first channel and the second channel. The combustion heater configured to be slidably removable from the AHU. An AHU for an HVACR system includes a housing with a fan section and a fan assembly disposed within the housing. The fan assembly including a pair of grooves slidably disposed on a pair of rails of the housing. The fan assembly configured to be both slidably removable from the AHU and liftably removable from the AHU.

Disclosed is an air heating apparatus including an expansion tank which preserves water, a water heater which receives heat from a combustion gas generated through a combustion reaction and heats the water, a heating heat exchanger which receives the water heated by the water heater and exchanges heat with air that is to be discharged for heating, a fan which sends the air to the heating heat exchanger, and a case, in which the water heater, the expansion tank, the heating heat exchanger, and the fan are disposed in an interior thereof.

Disclosed is an air heating apparatus including an expansion tank that preserves water, a water heater that receives heat from a combustion gas generated through a combustion reaction and heat the water, a heating heat exchanger that receives the water heated by the water heater and exchanges heat with air that is to be discharged for heating, a fan that sends the air to the heating heat exchanger, and a main passage connecting the expansion tank, the water heater, and the heating heat exchanger. The main passage includes a first part that is a part extending downwards from the expansion tank, and a second part communicated with the first part and the expansion tank, extending from the expansion tank, and one end of which extends upwards to be connected to the water heater.

Disclosed is an air heating apparatus including an expansion tank that preserves water, a water heater that receives heat from a combustion gas generated through a combustion reaction and heat the water, a heating heat exchanger that receives the water heated by the water heater and exchanges heat with air that is to be discharged for heating, a fan that sends the air to the heating heat exchanger, and a case, in which the water heater, the expansion tank, the heating heat exchanger, and the fan are disposed in an interior thereof.

Disclosed is an air heating apparatus including an expansion tank that preserves water, a water heater that receives heat from a combustion gas generated through a combustion reaction and heat the water, a heating heat exchanger that receives the water heated by the water heater and exchanges heat with air that is to be discharged for heating, a fan that sends the air to the heating heat exchanger, and a case, in which the water heater, the expansion tank, the heating heat exchanger, and the fan are disposed in an interior thereof.

An extreme condensing boiler includes cold and hot water headers, burner, and multi-tubing heat exchanger, so that cold water absorbs heat from exhaust gas of the burner being heated to medium-hot, which absorbs heat generated by the burner being heated to hot water through absorbing heat from both sides of tube portion of the multi-tubing heat exchanger, and so that the hot water is delivered to the hot water header, and a combustion air heat exchanger is provided around the multi-tubing heat exchanger. The condensing boiler uses dual/triple tubes for fire and water tubes, increasing efficiency by absorbing heat from both sides. The fire tube is surrounded by the cold water tube so as to minimize exhaust gas temperature and maximize condensing by absorbing waste heat. The condensing boiler realizes a direct fire boiler through the fire and water tubes, and an energy-saving tankless boiler including headers and tubes only.

A heat exchange cell for a heating boiler includes a casing with a sidewall enclosing an internal space, the sidewall having an open front end surrounded by an annular edge of the casing front end. A sheet metal annular closing flange has an opening and radially internal, intermediate and external flange edges. The radially external flange edge connects to the casing sidewall along the annular edge. The radially internal edge defines radially internal and external surfaces. A front edge surface connects the radially internal surface and radially external surface. The front edge surface defines a lying plane on which the front edge surface lies, the lying plane defining an axial direction orthogonal to the lying plane and passing through the opening, and a radial direction orthogonal to the axial direction. The radially internal surface extends parallel to the axial direction protruding towards an outside of the cell.

A hot water heater appliance includes a boiler, a companion water heater and a controller. The controller is configured to control the water heater appliance in response to a scheduled plurality of performance modes based on a preset schedule. A first performance mode is scheduled to be performed at an expected low usage time and a second performance mode is scheduled to be performed at an expected high usage time relative to the expected low usage time.

A kit for assembling a heating system and a heating system, which when assembled, comprises at least two heating devices, a partition constituting at least a part of one wall of each of the devices, which separates between interiors thereof, and a sealing arrangement mounted at least along upper, lower and rear edges of the partition to at least reduce a heat transfer between the interiors of the two devices at said edges so as to allow individual heating operation of each of the heating devices; the heating devices having a common front wall at least seen from an exterior of the system as a single front face of the system.