Abstract: A ducted unit including a sound-insulated housing having a sound absorption coefficient of at least 0.05 W/m2 at 100 Hz and wherein the sound-insulated housing contains an air circulation unit to draw air through the ducted unit, wherein the air circulation unit is operated to spin between around 1200 and 750 revolutions per minute.
Abstract: A ducted unit having first and second outlets wherein the first and second outlets are connected to each other by outlet ducting to form a closed loop, the outlet ducting having at least two spaced apertures for ejecting air within the outlet ducting at substantially constant pressure such that the air pressure within the closed loop outlet ducting is substantially equalized such that the outlets operate at a substantially constant pressure.