Abstract: A fuel-fired heating appliance, representatively a gas-fired water heater, has a combustion chamber in a lower end portion thereof, and fuel burner apparatus having main and pilot burner portions is operatively disposed in the combustion chamber. During operation of the water heater combustion air is supplied to the burner apparatus only via a duct structure having an inlet elevated relative to the floor or other horizontal support surface upon which the water heater rests. A flammable vapor sensor is mounted on the lower end portion of the water heater, externally of the combustion air supply duct structure and at an elevation lower than that of its elevated inlet, and is operatively connected to burner control circuitry which, in turn, is coupled to the burner apparatus. In the event flammable vapors are generated near the floor adjacent the water heater, the vapor sensor operates to detect such vapors and responsively disables the burner apparatus via the control circuitry.

Abstract: A fuel-fired water heater has a combustion chamber disposed above a wall ucture forming a flow path for combustion air being drawn into the combustion chamber during firing of the fuel burner portion of the water heater. A combustion air shutoff system is incorporated in the water heater and functions to sense an undesirably high firing temperature in the combustion chamber and responsively shut off essentially all further air flow to the combustion chamber and thereby terminate combustion therein. In various disclosed embodiments thereof, the combustion air shutoff system includes a damper member movable between an open position in which its permits air flow through the combustion air flow path, and a closed position which it blocks essentially all further air flow through the combustion air flow path. The damper is releasably held in its open position by a eutectic metal fusible link member positioned exteriorly adjacent an exterior wall of the combustion chamber.

Abstract: A fuel-fired water heater has a series of control and operating components which, with electrical power being supplied to the water heater circuitry via a power switch, are electrically actuatable in a predetermined sequence to supply combustion heat to water contained in a tank portion of the water heater to return the temperature of the water to a heated setpoint temperature in response to the water temperature falling below such setpoint temperature. LED diagnostic indicating lights are wired into the water heater circuitry in a manner such that each indicating light is associated with a different one of the electrically coupled components. As the components are sequentially actuated during a water heating cycle, the LED lights are successively illuminated.

Abstract: Multiple resistance type electric heating elements projecting into the interior of the storage tank portion of an electric water heater are protected against dry firing damage by using a water soluble member, representatively a sugar cube, positioned in the empty tank and blocking the spring-driven movement of a switch closure member that maintains an electrical circuit in an open state preventing electrical current flow through any of the heating elements. When the tank is initially filled with water the sugar cube dissolves, thereby unblocking the switch closure member and permitting it to be spring-driven into a circuit closing position to permit electrical current flow through the heating elements.

Abstract: A power vented water heater has a radiant gas burner located in a combustion chamber disposed beneath the storage tank portion of the water heater, and a draft inducer fan supported above the top end of the storage tank by a one piece molded plastic adapter fitting having a tubular body interconnecting the upper end of the water heater flue to the inlet of the fan, and a transverse outlet leg. A combustion gas discharge pipe is connected to the fan outlet, and an air intake pipe has a first portion connected to the outlet leg of the adapter fitting to deliver combustion gas cooling air thereto, and a second portion coupled to the burner inlet to deliver combustion air thereto along with gaseous fuel introduced into the second portion of the air intake pipe from an externally mounted gas valve. Integral orifice structures within the adapter fitting automatically maintain a predetermined ratio among the combustion gas, cooling air and combustion air flows.

Abstract: A fuel-fired, forced draft heating appliance includes a draft inducer fan having an inlet connected to a vent hood, an outlet connectable to a vent pipe, and an interior housing region in which a negative pressure is generated during normal appliance operation. The vent hood receives hot combustion gases generated by the appliance, and has an inlet for receiving ambient dilution air that mixes with and cools the combustion gases entering the hood and subsequently discharged into the vent pipe by the fan. A combination pressure and temperature limit control is used to sense the presence of an obstruction in either the vent pipe or the vent hood inlet and responsively shut down the appliance. The control includes a vacuum switch external to the fan, a bimetallic disc-type temperature sensor disposed within the negative pressure fan region, and a conduit interconnecting the switch and the temperature sensor.

Abstract: A fuel-fired water heater has a plurality of bottom end legs which hold the bottom end of the heater a few inches above the floor, and a fuel burner positioned directly above a combustion air inlet in the bottom end of the heater body. To assure that all combustion air delivered to the burner is taken from a height at least 18" above the floor, a bottom end portion of the water heater is positioned within a floor supported, horizontally enlarged drain pan which vertically extends to at least 18" above the floor. In one embodiment thereof, the drain pan has an open top through which combustion air enters and is drawn downwardly to the bottom air inlet of the heater, and in another embodiment the drain pan top is closed off and combustion air is ducted into the pan from a remote, higher location. The pan has an outlet fitting which may be connected to a pipe or hose to drain away any water leaking from the water heater, or from closely adjacent piping and/or fittings connected thereto.