Patent GB-438942-A (GB)
Title: Improvements in apparatus for cooling and ventilating buildings
IPC: F24F11/08
Filed: 1935-05-10
Abstract: 438,942. Conditioning air. DEHN, F. B., 103, Kingsway, London.-(Niagara Blower Co. ; 673, Ontario Street, Buffalo, New York, U.S.A.) May 10, 1935, No. 13826. [Class 137] [See also Group XIII] Apparatus for conditioning air comprises a cooling coil arranged in multiple sections or units over which the air is passed, in countercurrent to the cooling fluid within the pipes of the coil, and is cooled to an average temperature above its dewpoint. A valve in each coil unit controls the cooling fluid passing through it, and a thermostat in the enclosure to which the air is supplied progressively adjusts the valves to increase the cooling and dehumidifying effect. Recirculated and fresh air are passed through the coil in varying proportions, but some fresh air is always admitted. A sub-thermostat in the enclosure varies the cooling effect, and a master thermostat in the fresh air inlet controls the setting of the sub-thermostat. A stop thermostat in the enclosure responsive to the temperature controls the flow of air or cooling fluid when the setting of the sub-thermostat is too low for comfort. A heater responsive to a hygrostat in the enclosure prevents the relative humidity rising unduly when a large amount of cool and moist fresh air is being handled. The air is drawn by a fan 26 from the enclosure 5 through a return air duct 6 and louvres 7, fresh air entering through a duct 14 leading to chambers 13, 13<1>, the latter being always open, and excess air being exhausted by a fan 10 through louvres 11 and duct 9. The air to the enclosure passes through cooling coils 20 and, when required, through humidifying sprays 21, 22, and a steam heater 25. The cooling coils are arranged in tiered units 30 and the cooling is regulated either by controlling the number of units and the quantity of cooling water used, or by controlling the air supply. Water for the cooler is circulated in pipes 41, 42 through a cooler 37 cooled by a plant 35, the pipe 41 having three branches leading to diaphragm valves 43, 44 and 45 adapted to be successively opened, cooling water being first admitted to the lowest unit. Byepasses 47 are provided with diaphragm valves 48, 49, 50. The water delivered by the cooler is maintained at a constant temperature of about 40 F. by a thermostat 53 acting on the motor controller 55 which is also subject to a pressure switch 56 which stops the cooling plant when the water circulation through the cooling coils ceases. To recirculate the maximum amount of room air, the switch 111 is moved to the left, and the air pressure from pipe 71 which operates the motors 8, 12 and 16 is released to atmosphere the fan 10 being de-energized, louvres 11 and 15 closed, and louvres 7 opened. When switch 111 is moved to the right, the action of the louvres is reversed and the maximum of fresh air circulated. During the summer, a switch bar 70 is moved to the right causing a switch 86 to deliver power from a controller 83 to a con. troller 89 of the cooling water circulation pump 38. Movement of the switch 200 by the bar 70 prevents steam from entering the spray water heater 104, the electrical switch 86 and the air switch 200 rendering the humidifying system inoperative. Due to control by the master thermostat 72, and the sub-thermostat 74 through line 77, switch 79 and line 80, a snap relay 81 is actuated on increase of pressure, and delivers air from the main pressure supply line 71 to the controller 83 which energizes the pump 38 for the cooling liquid. The control line 77 from thermostats 72, 74 and 76 is connected through line 46 with valves 43, 44 and 45 controlling the water flow through the cooling coils 30, in conjunction with the byepassing valves 48, 49, 50. Should the outside air be relatively cool and moist, the stop thermostat 76 will bring about cooling of the air, but not enough to prevent the relative humidity rising too high, and to prevent this the hygrostat 90 acts on valve 95 and admits steam to the heater 25. The consequent rise in the air temperature results in the temperature of the cooling coils being lowered, and the dehumidification increased. During the winter, the bar 70 is moved to the left and the switch 86 renders inoperative the cooling system, and thermostat 76 causes admission of steam to the heater 25. The controller 83 is connected through the switch 86 with the motor 99 of the spray water pump 100 which is operated under control of the hygrostat 90 which is connected through switch 79 with the snap relay 31 The spray water passes through a heater 104 to relatively coarse nozzles 108, but if the humidification is insufficient, steam is supplied to the heater 104, and, if necessary a fine spray of heated water is supplied by nozzles 109. The thermostatic regulation of the flow of air through the cooling coils is shown in Fig. 3, louvres 122 and 121 controlling the air flow through the lowest coil 30, and a byepass 120 respectively, by an air motor 124 energized by the line 77 from the thermostats. The upper coils are similarly controlled by louvres 131, 132 from an air motor 127.