Patent GB-577658-A (GB)
Title: Improvements in or relating to steam supply systems for central heating and other purposes
IPC: F24D19/08
Filed: 1944-04-24
Abstract: 577,658. Steam-heated central heating systems &c. THORNHILL, R. H. April 24, 1944, No. 7547. [Class 123 (ii)] [Also in Group XXIX] A steam supply system for central heating &c. comprises a steam boiler 1 having a steam outlet pipe 2 with branches 3, 4 leading to radiators &c. from which branch pipes 5, 6, 7 return condensate to a receiver 8, the latter communicating through a pipe 11 with the water space of the boiler under the control of, a float 13, which is located in a chamber 9 in the form of a tube extending vertically from said receiver and substantially above the normal water level of the boiler, and the pipes 6, 11 both being fitted with non-return valves 10, 12 respectively. The float 13 is slidable between two stops 14, 15 fitted to a vertical rod 16, upon which is secured a piston valve 24 and which projects through the casing 18 of this valve and is connected to the central hinge link 23 of a spring-controlled toggle mechanism 20, 22 mounted on said valve casing, the valve 24, in its mid-position, Fig. 2, obturating ports 26, 28 which communicate respectively with an annular steam chamber 27 open to the boiler through a pipe 30 and with an annular chamber 29 open to the atmosphere through a vent pipe 32. In operation, and with a low-water level in the chamber 9, the float 13 rests upon the lower stop 15 of the rod 16 and the latter and its valve 24 are in the extreme downward position with a limiting abutment 34 on the rod contacting a fixed guide 17 in the chamber and with the steam ports 26 closed and air ports 28 open. As condensate flows into the chamber, however, the float gradually rises to contact the upper rod stop 14 with increasing pressure until the resistance of the toggle spring 21 is overcome, whereupon the rod 16 moves upwardly to its other extreme position, determined by a second abutment 35, to cause the steam ports 26 to be opened and the air ports 28 to be closed. The chamber 9 and receiver 8 are then exposed to the maximum steam pressure in the system, and consequently the condensate will be forced through the pipe 11 until the float falls and contacts the lower stop 15 again and, by its weight, forces the rod 16 down against the resistance of the spring 21 until the toggle mechanism operates with a snap action to effect return of the rod and its valve to their original positions with the steam ports 26 closed and air ports 28 open. Means, such as a slidable plunger 36 open to the steam side of the valve 24 and connected to the rod 16 by a rocker bar 38, may be provided for compensating differences in pressure on the two ends of the said rod, also means for adjusting the limit of movement thereof in accordance with variations in boiler pressure. The condensate may, if desired, be delivered from the reservoir 8 or chamber 9 to an elevated reservoir, through a pipe 48<1> fitted with non-return valve 49<1> and stop valve 50<1>, instead of to the boiler; alternatively the upper water space of the boiler may be connected with the receiver 8 by a pipe 48, having a return valve 49 and stop valve 50 for effecting positive circulation of water from the upper to the lower, parts of the boiler.