Abstract: An inducer (40) for causing a flow of combustion air into and gases of combustion through and out of a furnace (10) of the condensing type. The inducer is intended for use, without modification of its design or size, in a series of furnaces of the same basic design but having different heating capacities and therefore different requirements for flow through the induction flow path. The furnace design is such that a given furnace is capable of operation so as to provide a flow of air to be heated that is either up, down or horizontal with only minor field modification on installation. The inducer has two discharges (43), only one of which is used in a given installation. The other discharge is blocked with a plug (61) of special configuration that can vary the output of the inducer to ensure optimum flow of combustion air into and gases of combustion through and out of the furnace.

Abstract: Suction gas is used to cool the motor of a low-side hermetic compressor. The suction flow is divided. A small amount of the suction flow, e.g. 15%, is diverted to cool the motor and is recombined, via aspiration, with the main flow which is supplied directly to the inlet of the running gear of the compressor.

Abstract: A housing for a propeller or axial flow fan. The housing comprises an orifice portion, a stator element portion and a motor mount portion, preferably made in a single piece by casting in metal. The single piece construction makes possible the positioning of the axis of rotation of the fan to be used with the housing precisely coincident with the axis of the orifice and thus permits very small fan blade tip to orifice wall clearances to be attained, increasing the efficiency of the fan assembly and reducing its radiated noise. The inlet of the orifice is elliptical to promote attached flow. In a preferred embodiment, the motor mount portion of the housing also is configured to serve as the motor shaft end cap of the electric motor used to drive the fan. The number of parts in a complete fan, housing and motor unit in such a configuration is reduced to two, the fan and the motor, reducing the time required to assemble and install the unit.

Abstract: An axial flow fan blade (11) having an enhanced tip (12, 12') to reduce or eliminate tip vortices and therefore vortex induced noise. The enhancement is a rounded body extending from the blade tip and having faired ends (15, 16) but otherwise a generally circular cross section. The body conforms to the contour of the tip and extends from the leading to the trailing edge of the blade. The body may have either a generally constant cross section (12) or a cross section that decreases from its leading to its trailing end (12' ).

Abstract: A blade (14) for a centrifugal flow fan (11) having forward curved blades. The blade has a boundary layer trip (21) on its pressure surface (14). The trip promotes the transition of the boundary layer from laminar to turbulent flow and enables the layer to remain attached to the pressure surface for a greater distance. The increased amount of attached flow enables greater fan efficiency and reduces fan radiated noise. The boundary layer trip may be of a variety of configurations.