Abstract: A wet bulb sensor system for taking the wet bulb temperature of air. The sensor system includes an air passageway, a fan for drawing the air into and through the passageway, a filter disposed adjacent the intake of the air passageway, a temperature sensor for determining the temperature of air, a wet bulb sump opening upwardly into the passageway, a tank holding a quantity of replenishment water, a wick surrounding the lower end of the temperature sensor and extending into the sump, a water conduit communicating the tank with the sump, and an air conduit communicating the air space above the water in the sump with the space in the tank above the water therein.

Abstract: An improved variable air volume air distribution system for distributing air within the interior of a building. The variable air volume air distribution system includes an air supply plenum, a supply fan for transferring air from the air supply plenum into the interior of the building, a return air plenum for receiving air from the conditioned space of the building, and an exhaust fan for exhausting air from the return air plenum to the outside atmosphere. The improvement includes a first pressure sensor located in the air supply plenum for sensing the air pressure within the air supply plenum; a second pressure sensor located in the return air plenum for sensing the air pressure within the return air plenum; and control structure for causing the exhaust fan to exhaust air from the return air plenum at a rate proportional to the ratio of the air pressure within the air supply plenum and the return air plenum.