An exhaust adapter secures an exhaust tube relative to an exhaust pipe. The exhaust adapter is formed to have an annular shape enclosing a through hole, and is mounted on the outer peripheral surface of the exhaust tube and on the inner peripheral surface of the exhaust pipe by inserting the exhaust tube into the through hole. When the exhaust adapter is being fitted on the outer peripheral surface of the exhaust tube, the inner peripheral surface of the exhaust adapter presses the outer peripheral surface of the exhaust tube, and when the exhaust adapter is being fitted on the inner peripheral surface of the exhaust pipe, the outer peripheral surface of the exhaust adapter presses the inner peripheral surface of the exhaust pipe.

A vent apparatus is used to install a tankless water heater or similar equipment inside an attic without going onto the roof. The vent apparatus may include a main housing and an umbrella assembly movably disposed therein. The main housing (e.g., PVC pipe) is installed through the roof. The umbrella assembly may have a central rod with a flexible umbrella cover on top. The umbrella assembly is pushed up through the main housing until the umbrella cover exits the top of the main housing to cover it and prevent rain from entering the main housing. The bottom of the main housing is then connected to the tankless water heater. Additional embodiments are disclosed for tankless water heaters and other equipment with an air intake port and a gas exhaust port.

The gas exchange termination assembly overcomes the affects of fluid turbulence caused by wind, drafts, and air pressure. The invention can be applied to gas burning devices under 4,000 BTU input. Turbulent flow of gases at the gas exchange termination assembly are mitigated by the location of slots and openings in the gas exchange termination assembly for both intake air and exhaust gases. The gas exchange termination assembly is connected, coaxially through the building structural wall, to a sealed combustion system in order that all gases are drawn from and return to the same general location (directly) outside the building. The gas exchange termination assembly includes an intake air hood for intake air with additional intake air openings, an exhaust pipe with slots and a plug to move products of combustion at angles to the concentric pipe as the intake and exhaust gases enter and exit.

A vent apparatus is used to install a tankless water heater or similar equipment inside an attic without going onto the roof. The vent apparatus may include a main housing and an umbrella assembly movably disposed therein. The main housing (e.g., PVC pipe) is installed through the roof. The umbrella assembly may have a central rod with a flexible umbrella cover on top and an engagement member on bottom. The umbrella assembly is pushed up through the main housing until the engagement member hits the bottom of the main housing and the umbrella cover exits the top of the main housing to cover it and prevent rain from entering the main housing. The bottom of the main housing is then connected to the tankless water heater. Additional embodiments are disclosed for tankless water heaters with an air intake port and a gas exhaust port.

An exhaust adapter secures an exhaust tube relative to an exhaust pipe. The exhaust adapter is formed to have an annular shape enclosing a through hole, and is mounted on the outer peripheral surface of the exhaust tube and on the inner peripheral surface of the exhaust pipe by inserting the exhaust tube into the through hole. When the exhaust adapter is being fitted on the outer peripheral surface of the exhaust tube, the inner peripheral surface of the exhaust adapter presses the outer peripheral surface of the exhaust tube, and when the exhaust adapter is being fitted on the inner peripheral surface of the exhaust pipe, the outer peripheral surface of the exhaust adapter presses the inner peripheral surface of the exhaust pipe.

A heating apparatus can have a sealed combustion chamber, a burner, and various air channels to direct air into the sealed combustion chamber and to provide heated air to the desired area or environment such as an interior room. A channel can direct a flow of air along a face of the sealed combustion chamber to cool the face. The channel can be within or outside of the sealed combustion chamber. Alternatively, or in addition, the heating apparatus can be capable of operating as a direct vent device or as a vent free device.

A representative system includes: an inner stack defining a flow path to direct exhaust gasses from the exhaust air outlet of a heating appliance to an exhaust; an outer stack disposed about an exterior of the inner stack and being spaced therefrom to form a combustion air passage in a heat transfer relationship with the exterior of the inner stack; a combustion air opening disposed at the intake end of the outer stack configured to receive combustion air and provide the combustion air to the combustion air passage; an air dam positioned to terminate the combustion air passage; a combustion air conduit configured to direct the combustion air from the combustion air passage to the combustion air inlet of the heating appliance; wherein, in operation, heat is transferred from the exhaust gasses to the combustion air directed through the combustion air passage.