THE TOBIN VENTILATOR. (Knight.)
Fig. 9.
McKINNELL'S VENTILATOR. (Taylor.)
To assist the action of winds over the tops of shafts and chimneys, various cowls have been devised. These cowls are arranged so as to help aspirate the air from the tubes and chimneys, and prevent a down draught.
The same inlets and outlets which are made to utilize winds may also be used for the ventilation effected by the motion of air due to difference in the specific gravity of outside and inside air. Any artificial warming of the air in the room, whether by illuminants or by the various methods of heating rooms, will aid in ventilating it, the chimneys acting as powerful means of removal for the warmer air. Various methods have also been proposed for utilizing the chimney, even when no stoves, etc., are connected with it, by placing a gaslight within the chimney to cause an up draught and consequent aspiration of the air of the room through it.
Fig. 10.
VENTILATING THROUGH CHIMNEY. (Knight.)
The question of the number, relative size, and position of the inlets and outlets is a very important one, but we can here give only an epitome of the requirements. The inlet and outlet openings should be about twenty-four inches square per head. Inlet openings should be short, easily cleaned, sufficient in number to insure a proper distribution of air; should be protected from heat, provided with valves so as to regulate the inflow of air, and, if possible, should be placed so as to allow the air passing through them to be warmed before entering the room.[14] Outlet openings should be placed near the ceiling, should be straight and smooth, and, if possible, should be heated so as to make the air therein warmer, thus preventing a down draught, as is frequently the case when the outlets become inlets.