Patent GB-348720-A (GB)
Title: Improvements in and relating to ventilation systems
IPC: F24F11/75
Filed: 1930-02-21
Abstract: 348,720. Ventilating- systems. CARRIER ENGINEERING CO., Ltd., 24, Bucking- ham Gate, London. Feb. 21, 1930, No. 5849. Convention date, March 16, 1929. [Class 137.] Forced ventilation ; air, heating and conditioning. -In a method of ventilating an enclosure in which air having desired characteristics is supplied to the enclosure in volumes depending upon varying atmospheric conditions the total volume supplied is maintained constant by the addition of a complemental volume of air withdrawn from the enclosure. Air withdrawn from the enclosure 1, Fig. 1, by way of a duct 4 controlled by a damper 11 and fresh air from a duct 34 controlled by dampers 35, 36 pass through a mixing chamber 5 and conditioner 6 and the conditioned mixture is returned to the enclosure through a duct 9 by a fan 8. A pressure regulator 15 in the return duct 9 controls a damper 14 in a duct 13 by-passing chambers 5, 6 and serving to add to the conditioned air a comple. mental volume withdrawn from the enclosure. The duct 13 contains a steam heater 22 controlled by valves 26, 27 in branch pipes 23, 24 having capacity to raise the temperature of the air stream by say 5‹ and 15‹ respectively. These valves and all the air control dampers are actuated by means of compressed air from a supply 17 under the control of thermostats 29, 32 responsive to temperature conditions in the enclosure, the former operating to allow the passage of compressed air until a given temperature, say 74‹ is reached and the latter to prevent the passage of compressed air until another given temperature, say 71‹ is reached. In operation, assuming the enclosure to be at a low temperature, compressed air from the source 17 will pass through the thermostat 29, open the reverse-acting steam valve 26 and also pass through a pipe 40 and air motors 39, 42 to close the damper 11 and open the minimum fresh air damper 36. No compressed air passes through the thermostat 32 and under these conditions the direct acting steam valve 27 is open and the main fresh air damper is closed. Thus all the air withdrawn from the enclosure passes through the heater 22 working at full capacity and is mixed with a minimum of fresh conditioned air before being returned to the enclosure. The damper 14 will be fully open. When the temperature reaches 71‹ the thermostat 32 will allow the passage of compressed air to close the steam valve 27 and also allow compressed air to pass through a pipe 38 and air motor 37 to open the damper 35 to increase the supply of fresh air. The resulting increased pressure in the return duct 9 will cause the regulator 15 to reduce the supply through the duct 13. If now the temperature falls below 71‹ the previous conditions will be restored. If, however, the temperature rises above 74‹ the thermostat 29 will cut off the supply of compressed air thus closing the steam valve 26, opening the damper 11 and closing the damper 36. This will cause a corresponding closing of the damper 14 in the duct 13. A relief opening 2a may he provided in the enclosure for the displacemen, of some of the air. The pressure regulator 15 is preferably of the form shown in Fig. 3 and comprises a chamber 45 with a diaphragm 46. The chamber is connected to the total pressure tube 43 and movements of the diaphragm are transmitted by a lever 47 to a bleeder valve 53 controlling the passage of compressed air from the supply 17 to the operating motor 19. A spring 49 serves for adjustment. In a modified arrangement shown in Fig. 2, the damper 64 controlling the passage of recirculated air through the conditioner 58 and the damper 65 controlling the inlet of fresh air may be operatively connected by links 66, 67 and controlled by a thermostat 71 in or adjacent the outlet of the conditioner. A hygrostat 78 operates through an air motor 76 and a damper 74 to control the supply of air from the conditioner to the mixing chamber 59 and return duct 61. The total supply is kept constant by a pressure regulator 83 operating a damper 80 in the byepass duct 62.