Patent GB-332748-A (GB)
Title: Improvements in steam heating apparatus
IPC: F24D19/08
Filed: 1929-07-30
Abstract: 332,748. Triggs, W. W., (Dunham Co., Ltd., C. A.). July 30, 1929. Heating buildings. - A steam heating system supplying steam from one source to two separate radiating systems is provided with means including a single exhausting mechanism for simultaneously maintaining a different sub-atmospheric pressure in each of these systems. The boiler A supplies steam to a header 1 and thence to pipes H, H<1> supplying separate radiating systems L, I,'. The exhausting mechanism comprises a motor-driven centrifugal pump 5 drawing water through pipe 6 from a tank 7 and delivering it through ejector 8 back to the tank. The ejector draws air and condensate from the system through check valve 12 and accumulation of condensate in the tank 7 is prevented by a floatvalve 17 which allows the pump 5 to deliver the condensate through pipes 18, 2, back to the boiler. The motor driving the pump 5 is controlled by a starter 25 connected to control switches by wires 29, 30, in one of which is placed a switch 31 which is opened by a device 32 when the desired vacuum is reached in the pipe 11. The starter 25 is also controlled by a switch 34 operated by a float in a tank D into which condensate from the heating system drains. Steam is delivered to each radiating system through a cut off valve J and reducing valve K which is operated by a diaphragm in a casing 42 subject to the pressure in the low pressure main 40. The pressure maintained in the, main 40 can be regulated by adjustable weights 47, 48 acting, through levers, on the diaphragm. The steam is supplied to each radiator L through a valve 50 having an apertured plate 51, Fig. 2 proportioned according to the condensing capacity of the radiator. A steam trap 53 is arranged in each radiator outlet to allow only water to pass to the return main M, and thence through pipe 59 and strainer 22 to the tank D. An alternative path for the condensate is through pipe 63 and valve 64 to the tank C, where condensate from a system operating at a higher pressure may revaporize by expansion to the pressure in the exhausting apparatus. Condensate which does not evaporate passes through a float trap 67 to the exhausting device B. The tank C is connected by pipe 70, with check valve 71, and pipes 72, 72<1> to the supply mains H, H', and by alternative connections 74, 74<1> and steam traps 76, 76<1> to the return mains M, M<1>. Normally the, latter paths are closed, and one of the pipes 72, 72<1> is also closed, the one leading to the radiating system operating at the lower sub-atmospheric pressure only remaining open, so that steam from the tank C may pass to that system. If the pressure difference is insufficient to vaporize a material quantity of condensate in the tank C the pipe connection 74 or 74' alone may be opened, and the tank C connected to one of the return mains M, M'. The stearn trap 76 prevents steam from passing into the return mains, and condensate is returned from the exhaust pipe through a float trap 101 to the tank C. The supply and return mains H, M are connected by a pipe 77 having a check-valve 83 opening towards the pipe H, so that if the pressure in the supply side falls below that in the return side, the pressures are equalized and air or condensate is not held in the radiators or drawn back to the supply side. The two sides of the valve 83 are connected by pipes 84, 85 to a chamber N having a diaphragm under spring pressure sufficient to balance the desired pressure difference between the supply and return sides of the system. When this pressure difference is too low, a switch 86 is closed and either the motor E or solenoid valve F is energized. A double-throw switch G is provided for each branch of the heating system, and is connected by wires 29, 30 to the motor starter 25, and by wires 93, 94 to the solenoid valve, F. Normally, one of the switches 87, 87<1> will be closed in one direction and the other in the other direction according to which radiating system is operating at the lower pressure or higher vacuum. Another equalizing connection 97 with a check valve 98 is provided between the lower ends of the discharge mains M, M<1> and the pipe 18 leading back to the generator. Assuming that the radiating system L is to operate at a lower temperature and pressure than L', the switch 87 is closed so as to place the conroller N in control of the motor E, and the switch 87<1> is closed so as to place the controller N' in control of the solenoid valve F. The valves are set so that the return main M discharges into the tank D and thence to the exhauster B, while the return main M' discharges into the tank C. The reducing valves K, K<1> are, set so that the supply main H<1> is at a higher sub-atmospheric pressure than the supply main H, and the outlet 70 from the tank C discharges into the main H when the valve F is opened. If the pressure difference in the system L<1> is too small, the controller N<1> will close switch 86<1> and open solenoid valve F to place the tank C (which communicates with the discharge main M<1>) temporarily into communication with the main H which is at a lower pressure. Condensate in the tank C is thus revaporized and passes into the main H. When the pressure difference between the tank C and supply main H is insufficient, the valves are set so that the tank C is connected directly to the return main of the lower pressure system. Alternatively, both the radiating systems L, L<1> may be operated at the same pressure.