Importance

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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. This assures that enough torque is always available to restore the valve to its closed (or open, in a normally open case) position, after the motor is de-energized, but that there is not too much torque for the motor to overcome when it moves the valve into the open position.

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First Claim