Abstract: A plate-type heat exchanger is shown wherein certain of the passageways thereof have been specially modified to include a downcomer to provide improved reflux nonadiabatic rectification capabilities.

Abstract: Three embodiments of an air distributor apparatus are shown which utilizes a balanced type air flow control valve of cylindrical configuration co-operatively associated with a cylindrical sleeve having circumferentialy spaced openings closed by the valve. A diaphragm powered valve actuator is disposed within the sleeve which is installed at the air inlet of an air distributor plenum. Several control schemes are disclosed.

Abstract: This specification discloses a method of making a high efficiency gas-fired furnace with aluminized steel heat exchangers which are specially prepared for higher heat exchange efficiency by heat treatment of the heat exchanger shells.

Abstract: A vane axial flow fan is shown having a shroud construction which provides greater than normal rigidity in the areas co-extensive with the stator vanes and fan wheel blades. Further, a novel method of constructing an axial flow fan is disclosed wherein the stator vanes are first mounted on an expandable split ring which is then placed within an annular stator housing. The split ring is then expanded to reduce stator vane end clearance prior to being permanently secured in place by welding.

Abstract: Three embodiments of an air distributor apparatus are shown which utilizes a balanced type air flow control valve of cylindrical configuration co-operatively associated with a cylindrical sleeve having circumferentially spaced openings closed by the valve. A diaphragm powered valve actuator is disposed within the sleeve which is installed at the air inlet of an air distributor plenum. Several control schemes are disclosed.

Abstract: An electric heater control circuit is shown which utilizes a 10-step controller for obtaining eighteen steps of heating control. Electrical and magnetic control circuitry operates this 10-step controller effectively through two cycles, one at a low level power output mode and a second at a high level power output mode, to thereby substantially increase the effective number of steps of heat control. In addition, means are provided for instantaneously energizing or de-energizing a plurality of small electric heaters upon shifting modes to compensate for the de-energization or energization respectively of a large heater to thereby avoid momentary periods of excess heat or cold while the controller is shifting modes.