Abstract: An wet-rotor hydronic heating/cooling circulator in which a check valve is positioned at the inlet eye of the pump impeller, where it can easily be serviced by removing the circulator motor and impeller. The check valve is preferably in the form of a valve subassembly that is removably inserted into an opening at the eye.

Abstract: A zone valve for a hydronic system (either heating or cooling) in which a motor-driven actuator rotates a ball valve through approximately 90.degree., between closed and opened positions. The ball valve provides lower flow resistance than that of conventional heat-motor and motorized zone valves, allowing the use of lower rated pumps, and allowing a single size valve to serve most applications. A restoring torque is provided by a tension spring so configured that it provides sufficient restoring torque to overcome the frictional torque of the ball valve. The restoring torque is kept from building up during rotation by configuring the spring in such a manner that its force varies inversely with the effective moment arm. The restoring torque varies by no more than 20% (preferably no more than 10%) during rotation of the ball valve.

Abstract: A zone valve for a hydronic system (either heating or cooling) in which a motor-driven actuator rotates a ball valve through approximately 90.degree., between closed and opened positions. The ball valve provides lower flow resistance than that of conventional heat-motor and motorized zone valves, allowing the use of lower rated pumps, and allowing a single size valve to serve most applications. A restoring torque is provided by a tension spring so configured that it provides sufficient restoring torque to overcome the frictional torque of the ball valve. The restoring torque is kept from building up during rotation by configuring the spring in such a manner that its force varies inversely with the effective moment arm. The restoring torque varies by no more than 20% (preferably no more than 10%) during rotation of the ball valve.

Abstract: A zone valve for a hydronic system (either heating or cooling) in which a motor-driven actuator rotates a ball valve through approximately 90.degree., between closed and opened positions. The ball valve provides lower flow resistance than that of conventional heat-motor and motorized zone valves, allowing the use of lower rated pumps, and allowing a single size valve to serve most applications. A restoring torque is provided by a tension spring so configured that it provides sufficient restoring torque to overcome the frictional torque of the ball valve. The restoring torque is kept from building up during rotation by configuring the spring in such a manner that its force varies inversely with the effective moment arm. The restoring torque varies by no more than 20% (preferably no more than 10%) during rotation of the ball valve.

Abstract: Tubs are supplied with hot water through a water circulation system including a pump, an elongate electric flow-through heater, a water filter and piping connecting that pump, elongate flow-through heater and water filter in series in that water circulation system. The pump, elongate flow-through heater and piping are arranged in a horizontal plane so that water flow passages in that piping, in the elongate flow-through heater and in the pump are intersected by that horizontal plane extending along directions of water flow in the mentioned water flow passages. The pump may be provided with a water inlet and a water outlet both lying in the same horizontal plane as the elongate flow-through heater and piping. The pump also may be provided with an axis of rotation, and even with an electric drive motor, extending in that horizontal plane. The elongate flow-through heater may be provided with an elongate structure molded of an electrically insulating synthetic resin for housing an electric heating element.

Abstract: An outdoor heating appliance includes a top structure having a top surface, a stationary airfoil, and exhaust openings for flue products. The operation of the heating appliance is rendered wind resistant by generating with the stationary airfoil, in a region above the top surface and in repsonse to wind, an air pressure lower than an air pressure of that wind, and by locating the exhaust openings in that region, whereby the flue products are exhausted from the outdoor heating appliance by the wind. An inlet opening may be provided below the top surface at the airfoil for receiving part of the wind, in order to sustain combustion and generate inside the heating appliance positive pressure toward the exhaust openings by guiding air from the received part of the wind through a channel to a burner in the heating appliance.

Abstract: Water heating methods and apparatus feed a combustible mixture of gas and air to an axial inlet of a cylindrical radiant surface burner and conduct water to be heated through a heat exchanger encompassing that cylindrical radiant surface burner as a cylindrical structure having first passages for combustion gases therethrough substantially radially of the cylindrical radiant surface burner and the heat exchanger.