Patent GB-332747-A (GB)
Title: Improvements in steam heating apparatus
IPC: F24D19/08
Filed: 1929-07-26
Abstract: 332,747. Triggs, W. W., (Dunham Co., Ltd., C. A.). July 26, 1929. Heating buildings.- Steam heating apparatus of the kind described in Specification 291,134 in which steam is supplied at varying sub-atmospheric pressures while a fixed pressure difference is maintained between the inlet and outlet of the radiators, is provided with a single exhausting device adapted to maintain the desired pressure difference in each of a number of separate radiating systems supplied from a single source through means which independently determine the sub-atmospheric pressure in each system. Steam is supplied from a generator A, Fig. 1, to three separate radiating systems B, C, D, associated with a single exhausting device E. The supply main 5 is provided with a cut-off valve 6, normally open, and a reducing valve 7 which may be controlled by a diaphragm in a casing 10, subject to the pressure in the main 8 on one side and to atmosphere on the other side. The pressure in the main 8 is determined by adjustment of the weights 15, 16 acting through lever 12 on the stem 9. Steam passes to each radiator 17 through a pipe 18, and a thermostatic steam trap 20 is provided between the radiator and the return main 22 to allow condensate only to escape from the radiator. Condensate in the supply main 8 is also returned to the return main 22 through trap 23. An equalizing pipe 24 with non-return valve 25 is provided between supply and return mains. Pressure control pipes 29, 30 extend to a differential pressure controller 31 which may be constructed as described in Specification 291,134. When the pressure difference falls below the desired minimum, a switch 32 is closed, the motor-starter 34 actuated, and the motor 36 and exhausting device E started. Each radiating system is provided with its own controller 31, so that the motor 36 is operated as long as any one of the switches 32 is closed. The motor 36 drives a centrifugal pump 37 which draws water from a tank 39 and delivers it into pipe 40 and thence through one or more of the ejectors 40a and pipe 41 back to the tank 39. Air which is withdrawn from the radiating system by the ejectors escapes through pipe 42 and check valve 43. Condensate accumulates in the tank 39 until a float 44 opens valve 46 in a pipe 47, when water is delivered by the pump 37 through the pipe 47 back to the generator A. An ejector unit is shown in Fig. 4. The casing 50 is mounted on the inlet pipe 40, and the water from nozzle 54 and condensate and air drawn in at 57 are discharged at 58 into the pipe 41. The stem 62 of a valve 61 is secured to diaphragms 65, 67, the space between which is open to the atmosphere. Pipes 73, 74 admit and discharge a control pressure fluid, preferably water, the pipe 74 having an apertured plate 75 to allow pressure to be built up in the chamber 69. The pump pressure maintains the valve 61 closed, unless sufficient pressure exists in the chamber 69 to open the valve. Pressure fluid is admitted to the chamber 69. by a pilot valve 78, Figs. 1 and 5, in which a valve member 83 controls the passage of pressure water from the main 40 through pipe 104, 105 to pipe 73 leading to the chamber 69 in the ejector unit. The valve stem 85 projects through stuffing box 87, and is connected to a yoke 88 through which a pivoted weighted lever 89 projects. An upward extension 92 of the valve stem is connected to an operating diaphragm 93, arranged between two smaller diaphragms 96, 97 which take the place of stuffing boxes, and are subjected on their outer sides to atmospheric pressure. The low and high pressure sides of the radiating system are connected by pipes 100, 102 to the chambers 101, 103, so that the diaphragm 93 is subject to differential pressure. When this falls below the desired minimum, the weight 91 opens the valve 83, admitting pressure fluid to the chamber 69, Fig. 4, and allowing the ejector to operate to restore the required pressure difference. The various radiating systems B, C, D have their reducing valves 7 set according to the heat requirements, and a constant pressure difference is maintained in each system by its pressure controller 31, switch 32, and the common motorpump unit 36, 37. The controller 78 of each radiating system determines whether the ejector associated with that system shall be effective or not, while the controller 31 starts the pump unit if not already operating in connection with another radiating system.