GB576666A - Improvements in or relating to gas-fired water heaters - Google Patents

Abstract

576,666. Gas-fired water heaters. PEET, A. Dec. 30, 1943, Nos. 21834/43 and 13394/44. [Class 64 (i)] [Also in Group XXIX] In a gas-fired geyser in which the gas valve 13, Fig. 2, is self closing and is controlled by a diaphragm or piston 47 subject to the differential pressures at the mouth and throat of a venturi passage in the water conduit, a hollow plug check valve 76, Fig. 3, with a small through bore is situated in the passage between the throat of the venturi and the space on the upper side of the piston to permit slow opening of the gas valve, when the water is turned on, and quick closing when the check valve is unseated due to the water being turned off. Valve 13 is loaded by a spring 15 or by gravity. Piston 47 is subjected on its lower face to the pressure of the water as it flows from the inlet 6 to the heating coil, the water first passing through a filter 54 and then through a governor valve consisting of a throttle 50 attached to 'the piston by a stem passing through an aperture in a disk 52. A reduced pressure is created in the chamber 48 by allowing the water to flow through a venturi 68 and taking off radial connections 72 from the throat of the venturi, past the check valve 76, to the space 48. The venturi is formed in a rotary plug cock 64 provided with grooves 70 which permit the cock to act as a temperature selecter by allowing water to by-pass the venturi and flow direct to the heating coil. A direct connection between the inlet 6 and the outlet 8 allows cold water to by-pass the heating coil, this connection being controlled by a manually actuated valve. Gas enters at 9, passes through a filter 31, past a governor consisting of a light diaphragm 30 with peripheral legs 29 which can contact a flanged aperture in a spring-pressed diaphragm 27, through passage 36 to a plug cock 12, and through an axial bore in the plug cock to a central duct housing the valve 13. A pilot burner 20 is also supplied from the plug cock 12, and the flame from this burner acts on a bimetallic strip 19, the upper part of which engages between collars 23 on the stem of a further valve 18 in the supply pipe to the main burner 7. Should the pilot flame fail, the bi-metallic strip will close the valve 18 and shut off the supply from the valve 13 to the burner. The plug cock 12 also acts as a valve for the main gas supply and it is provided with an operating knob 42 and an indicator 43. The gas supply unit is mounted on, and detachable from, the water supply unit, the actuating stem 46 carried by the piston passing through a packing gland and contacting the stem 38 of the gas valve. The heating pipe 2, Fig. 1, is made in two lengths coiled around a shell 85 fitted with a finned heat exchanger 86. The two lengths of pipe are brazed and held together by a clip 116 and are positioned along with the shell 85 by spring clips 152. In a modification, the piston and gas valve move in the horizontal direction. Specification 576,682 is referred to.