Abstract: A multi-zone HVAC system, including: (a) a hollow curb to be mounted to a building roof, (b) a hollow base mounted on or in the curb, the base having a paratition thereacross; (c) a hollow working unit mounted on the base, the working unit containing a cooling coil, a fan, and a heater so that return air from the building can pass through the curb and base to be heated or cooled in the working unit and then directed through the base and curb into the building, the portion of the base below the working unit having height of less than 24 inches.

Abstract: An improved school room ventilator of the type having a cabinet to be positioned against an outside wall of the room, the cabinet having an inlet port, an outlet port and containing a fan, the inlet port for drawing fresh air through a duct in the outside wall, through the inlet port to the fan and then through the outlet port into the room, the ventilator optionally containing means for heating and/or cooling the air and/or means for recycling air from the room through the ventilator and then back into the room. The improvement of the instant invention relates to the cabinet of the ventilator, the cabinet being a corner cabinet so that the ventilator can be positioned in a corner of the room.

Abstract: A releasing engaging means, which is manually manipulated, and is fixably attached over a typical female plug or receptacle that is connected to the mains is used to fixedly hold, a male plug into the receptacle and to inhibit its removal from the receptacle unless the releasing engaging means is manually manipulated, thus inhibiting erroneous removal of the plug as by pulling the cord to which it is attached. Specifically the mechanism provides a "hinged door" mounted in proximity and above the female receptacle. The plug passes through the doors as they swing open and the edge of the doors urge against the plug to hold it in the socket. The doors may be manipulated away from the plug by movement through integral extending tags that are integral to the doors which then release their frictional urging engagement with the plug.