Abstract: A spring assembly for counterbalancing a door includes a compression spring and tension members engaging opposite ends of the spring. The tension members can be connected in a conventional door mechanism, the assembly replacing ordinary tension springs of the mechanism. The tension members and the spring are maintained in axial alignment during compression of the spring, which can be preloaded as desired. The assembly is fail-safe in that the spring is completely enclosed and the spring, if broken, continues to provide support for the door.

Abstract: A spring assembly for counterbalancing a door includes a compression spring and tension members engaging opposite ends of the spring. The tension members can be connected in a conventional horizontally pivoted door mechanism or a track-guided door mechanism, the assembly replacing ordinary tension springs of the pivoted mechanism. The tension members and the spring are maintained in axial alignment during compression of the spring, which can be preloaded as desired. Provision is made for an initial preload corresponding to a lowered position of the door, facilitating installation and adjustment of the spring assembly. The assembly is fail-safe in that the spring is completely enclosed and the spring, if broken, continues to provide support for the door. In the track-guided mechanism, the spring assembly is connected between an anchor and a driveshaft pulley by a cable that is wound onto the pulley.

Abstract: A control arrangement for a water heater system that includes a water heater having a heating element, an alternate heat source which is preferably a solar collector panel, and a heat exchange and storage unit containing a phase change material therein for storing heat energy from the alternate heat source and for transmitting the stored heat to the water in the water heater when available and when needed. The control arrangement includes means for programming the system to operate in one or more of several different operating modes, including a mode in which the heating element is deenergized at all times, a mode in which priority is given to using stored energy rather than heating element energy, a mode in which both the stored energy and the heating element are utilized simultaneously, and a mode in which the heating element is deenergized during predetermined time periods. The control may also be programmed to select which modes are used during selected time periods of each day of the week.