Abstract: A remotely controlled, reversible drive motor is mounted on an extension of the upper end of a chimney below a protective housing enclosing a spiral cam drive mechanism converting rotational movement of the motor into vertical linear motion of a cap laterally spaced from the housing in axial alignment with the chimney extension. Guided movement is thereby imparted to the cap between a closed chimney sealing and open positions.

Abstract: A housing supporting a signal-controlled, power operating unit for a damper is mounted internally within a duct by a tubular supporting sleeve in an angularly and axially adjusted position projecting from an open end of the duct. A shield fixed to the external end of the sleeve backs an annular sealing flange engaged by the damper element, which is enclosed by a flow deflecting hood slidably assembled on the shield.

Abstract: A normally energized motor maintains a counterbalanced damper closed to block air inflow in a non-combustion condition of an appliance. Deenergization of the motor by thermostat control releases a rotor for displacement through a limited angular stroke. Through a lost-motion linkage connection the damper is displaced, in lagging relation to the rotor to the open position. The open position of the damper is detected by a sensor to open a fuel valve in the appliance.

Abstract: An interior building area containing at least one combustion type heating appliance is equipped with a combustion air inlet having an openable and closable damper operatively associated therewith. The damper is weighted for gravity closing and is suspended from a swinging pivot in a manner to assure a substantially airtight closure for the combustion air inlet. In addition, actuator structure is provided for each combustion-type heating appliance within the interior building area and operatively associated with the damper for moving the latter to an open position responsive to operation of at least one of the heating appliances.