Patent GB-414674-A (GB)
Title: Improvements in or relating to the control of atmospheric temperature produced by steam heating systems
IPC: G05D23/275
Filed: 1933-01-02
Abstract: 414,674. Valves. DUNHAM CO., Ltd., C. A., 1523, Davenport Road, Toronto, Canada. Jan. 2, 1933, No. 44. Convention date, Jan. 8, 1932. [Class 135.] In a steam heating system for buildings, the temperature is regulated so that it is relatively higher when the humidity decreases, and lower when the humidity increases. The steam admission valve is controlled by an electric motor operated in response to a device, Fig. 5, sensitive to temperature and humidity which acts to close the valve positively or to permit its opening movement. The sensitive device, Fig. 5, comprises an electric resistance coil 121 with a sliding contact 126 carried by a pivoted arm 140. A heat-sensitive capsule 132 contains an expansible fluid, and a bellows 134, the movements of which actuate the arm 140, to an extent determined by an adjusting screw 139. An adjustment of the rate of movement of the arm 140 relatively to the resistance is provided by a screw 145 which adjusts the fulcrum 144. The hygrostat comprises a strip 147 sensitive to moisture, one end of which is connected to an adjustable member 149 and the other end to a pivoted lever which actuates toothed mechanism 164 to move the resistance 121 bodily. The position of the contact 126 on the resistance 121 is therefore determined by the combined effect of temperature and humidity. Fig. 3 (not shown), illustrates a graphical method by which the temperature which should be associated with a given humidity to give a constant condition of comfort, is determined. Fig. 8 shows the control system for the electric motor which actuates the steam admission valve. The three contacts 123, 125, 126, Fig. 5, are connected to wires 173, 174, 175, Fig. 8, so that the relative strengths of the magnetic fields produced by the two parts of the solenoid 176 correspond to the position of the contact on the resistance 121<1>, 121<11>. The movement of the solenoid core operates a contact 219 which causes field winding 197 or 198 of two electric motors to be excited. The corresponding armature 195 or 196 is thereby rotated (in opposite directions), and actuates the steam control valve through worm gearing 200. The Specification as open to inspection under Sect. 91 comprises also an electric control system, Fig. 10 (Cancelled, not shown), including two thermostat-hygrostats, one for day and one for night use. The latter, or both, may respond to temperature only, and several such instruments may be located in different parts of the building. A switching system is described by which either thermostat-hygrostat, or a manual control, may be brought into operation, and a clock control is also included. The system operates signal lights to indicate the conditions under which it is operating, and comprises also means for controlling an exhaust pump for maintaining sub-atmospheric pressure in the heating system. Fig. 1 (Cancelled), illustrates the arrangement of apparatus in the heating system. Steam flows from a boiler A through main B and control valve C to radiators D. Condensate returns through steam traps E, return main F tank G and exhausting mechanism H controlled by a differential pressure device J. The valve C is controlled electrically by thermostat-hygrostats L, L<1> through a control panel M. The exhausting mechanism H comprises a separator tank 6 and motor-driven pump 7 by which water is circulated from the lower to the upper part of the tank through an ejector 9 which withdraws gases from tank G. A float - controlled mechanism 14 causes the return of excess water to the boiler. The motor 8 driving the pump 7 is controlled by the device J through starter 22, to ensure the required pressure-difference on the inlet and outlet sides of the system. A pipe 27 with check valve 30 connects the supply and return mains, to equalize pressure if at any time the pressure in the supply mains is lower than in the return mains. Fig. 2 (Cancelled), illustrates the control valve C, which is of double beat type, the ports 34, 35, being connected to the boiler and supply main respectively. The parts 46, 48 of the casing are separated by a flexible diaphragm 50, open on the lower side to the atmosphere and on the upper side through pipe 56 to the part B<1> of the supply main. The condensate above the diaphragm prevents undue heating by steam. A similar diaphragm 64 is enclosed in a casing 60 open on the upper side to the atmosphere and on the lower side through pipe 68 to return main F. A lever 90 adjustably loaded by a weight 95, is pivoted at 91, and connected at 94 to a yoke on the valve rod. The valve is therefore subjected to the pressure difference on the supply and return sides of the system, counter-balanced by the weight 95. The two closure members of the double heat valve may be of different sizes, with corresponding differences in the diaphragms. The valve is actuated by the electric motor control mechanism 110 illustrated in Fig. 8 through a pivoted lever 99. This subject-matter does not appear in the Specification as accepted.