GB928372A - Improvements relating to electric water heaters - Google Patents

Abstract

928,372. Electric water heaters. SIMPLEX ELECTRIC CO. Ltd. July 8, 1959 [July 14, 1958], No. 22440/58. Class 39 (3). In a water heater having an electric heating element and inlet means 16 and outlet means, there is a steam vent 18 at the top of the vessel and a baffle-plate 43 between the mass of water being heated and the steam vent 18, steam passing through the constricted annular gap between the baffle-plate 43 and the container body 20. The baffle-plate 43 is preferably of tinned copper and prevents water from entering the steam vent 18. The electric heating element comprises (a) a length of resistance wire mounted between sheets of mica clamped to the underside of the base-plate 10 or (b) an electric heater having a tubular sheath clamped or fused to the underside of the baseplate 10 or (c) a resistance wire embedded in electrically insulating thermally conducting cement is placed in a groove or grooves in the underside of the brass pressing base-plate 10. A control device 28 mounted below base 10 for regulating the current supply to the heater comprises a thermally sensitive element (bimetal strip) switch means and manually operable adjustment means for the switch means. The switch means is mounted on a chassis which is pivoted relatively to the base-plate 10 by the adjustment means, so moving the actuating member of the switch means towards and away from the free end of the bimetal strip to vary the set temperature. The adjustment means comprises a cam or screw mechanism operated by a control knob mounted on a spindle 31. A signal lamp is illuminated whenever the switch means supplies full current to the heating element but not when the switch means reduces the current to a lesser value or to nothing; in this way the base-plate can be kept at a set temperature. The switch means is such that its contact elements open and close by displacement of a metal strip or plate from one stable position to another; the switch contacts open if no water is present. A nut and washer assembly 40 is threaded internally to screw on to the steam vent pipe so as to make a water-tight joint between casing 20 and a moulded rubber member 35 of U-section. A whistle 42 gives warning of boiling. Specifications 928,371 and 928,373 are referred to.