A stall-type enclosure for use by a golfer at a driving range having an under-floor plenum for receiving heated air and allowing it to rise through a grating covering the plenum in an area around a mat structure upon which the golfer stands. The plenum is surrounded by an insulating wall and heat either leaking or radiating from the sides of the plenum also rises through the grating from the insulated region. The enclosure has a rearwardly pitched roof providing a space behind the front wall and above the opening therein for collection of heated air which is returned to a rear compartment of the structure wherein the heater is located. The mat structure is preferably movable on the grating to allow positioning for optimum wind protection, and hinged flaps or dampers may be selectively placed in covering relation to portions of the grating to concentrate the areas through which heat rises. A ball container is preferably positioned adjacent the mat structure to receive heat rising through the grating.

A ventilator for mounting on a sloping roof has a pair of trapezoidal side members. The uphill ends of the side members are less slanted than the lower ends. Covering members extend between the side members to define an opening along the upper bases of the side members through which air may exit from a hole in the roof of the building.

A roof ventilator comprises a base plate insertable in a roof assembly and having an opening receiving a panel leaving a free passageway at the lower end. The panel having a plurality of pairs of transverse louvers defining louver openings. Alternate louvers extend outwardly and upwardly and outwardly and downwardly from the panel, the cross-sectional area of the louver openings tapers outwardly and the endmost louvers converge outwardly of the panel. A projecting ridge is formed in the base plate beyond the lower transverse edge of the passageway and has an upper side which is connected by a step to an inclined section of the bottom wall of a duct communicating both with the louver openings and passageway and the attic or rooms below. Irrespective of the direction of currents of air flowing along the roof negative pressure is produced inside the duct.

A vented baffle system for use in a clarifier tank having a tank bottom, a periphery and a substantially vertical peripheral wall bounding the interior of the tank is formed by a plurality of individual and cooperatively-engageable baffles mounted on the peripheral tank wall. Each baffle includes a panel member that downwardly slopes from the peripheral tank wall toward the interior of the tank and the tank bottom and terminates at a lower edge disposed in space relation above the tank bottom. A first lateral end of the panel member unitarily carries an end bracket securable to the peripheral wall for supporting the panel member in a cantilevered fashion. One or more of the baffles are provided with a relief valve means for venting the pressure in a space formed between the junction of the lower side of the panel member and the peripheral tank wall. The resulting system provides a vented baffle system in which pressure exerted by the build up of gases in the space may be alleviated.