GB998850A - Air conditioning system - Google Patents

Abstract

998,850. Control systems for air-conditioning apparatus. SINGER CO. April 26, 1962 [April 26, 1961], No. 15993/62. Heading H2H. An air-conditioning system for maintaining various zones of a building at individually selected temperatures comprises a plurality of separate air-conditioning units, a central control switch common to all the units and an individual switch assembly associated with each unit to allow the units to be controlled either as a whole or individually, the central control switch being momentarily opened periodically to de-energize all the units after which each unit can be re-energized by means of an associated manually-operated switch. With the switches 34 in each of the rooms 2, 4, 6 closed, closure of the main switch 12 will initially energize the heaters 52 of the bimetal switches 42 which are arranged to have different operating characteristics. As the bimetal strips 50 are heated so as to move to the right (as shown), contacts 54, 56 first close and then open. When closed, these contacts cause energization of the coils 40 of relays 46, closing self-maintaining contact 41 and a further contact 43 which completes the circuit for the compressor 14 and fans 24, 28 of the air-conditioning units. Should any unit not be required, its operation can be terminated by opening the associated switch 34. In order to prevent operation of the air-conditioning units when rooms are unoccupied the main switch 12 is arranged periodically to be opened and immediately reclosed automatically by means of a motor 138 and cam-operated switches 126, 128. Opening of the main switch 12 de-energizes relays 46, thus removing the supply from the air-conditioning units. The immediate reclosure of switch 12 does not re-energize relays 46 since bi-metal switches 42 remain heated and in the right-hand position. Should any room now be occupied the associated air-conditioning unit can be restarted by closure of switch 44 to energize relay 46. The system is shut down by opening switch 12. The switch 12 may be manually-operated by means of switches 125, 127 and the switches 42 are given random operating characteristics so as to prevent heavy starting current.