GB969953A - Improvements in or relating to heating systems employing circulating liquids under pressure - Google Patents

Abstract

969,953. Pressurized heating systems. PRESSURISATION Ltd. Nov. 11, 1960 [Nov. 11, 1959], No. 38177/69. Heading F4U. A pressurization unit for a closed circuit heating system comprises an expansible and contractible over-spill tank 1. The latter is mounted on a frame structure 2 which accommodates a high pressure vessel 3 and pumps 4 and 5, a cylinder 10 of compressed nitrogen being mounted inside or outside said frame. Spill liquid due to expansion in the heating system and vessel 3 is stored in tank 1 in the space between the walls of the tank and a bellows 11 having its upper end secured to inwardly turned flanges on the side walls of the tank and its lower end closed by a metal plate 12 which carries hollow metal balls 13 acting as floats. The tank cover 14 is removable and is provided with a vent 15 communicating the interior of the bellows to atmosphere. Leakage and evaporative losses are made up through a mains inlet 16 controlled by a float valve 26, which opens the inlet at a predetermined minimum liquid level, and an overflow chamber 19 with a float operated outlet is provided. At all stages of expansion and contraction of the tank only a small constant amount of air is contained in the tank, aeration of the liquid being thus minimized. Liquid is supplied to the tank via conduit 23 through a pressure controlled solenoid valve 6, an alternative path being provided in the event of failure of the latter through a spring-loaded relief valve 6a. On contraction of the liquid in vessel 3 pumps 4 and 5 are automatically brought into operation to return liquid to the said vessel via conduits 23 and 24. The pumps are arranged to operate in tandem, one cutting out as the predetermined working pressure is approached and the other then operating to " top-up " the pressure as and when required.