GB659084A - Electric liquid heating system - Google Patents

Abstract

659,084. Automatic temperature-control system. LEMERCIER FRERES. June 17, 1948, No. 16299. [Class 38 (iv)] [Also in Group XI] An automatic temperature control system, Figs. 1 and 2, having at least one electric heating element 4 for heating liquids to either of two predetermined temperatures, comprises two thermally - actuable switches 7 and 8 arranged between one of the poles of an electric supply source 1, 2 and one end of the heating element, the first thermally-actuable switch opening at the lower and the second thermally-actuable switch 8 opening at the higher of the two temperatures, a manually-operated switch 9 being arranged to bring out of action one of the thermallyactuable switches at will whilst the other remains in the circuit. The thermally-actuable switches may be thermostats. If the thermostats are in series, Fig. 1, the manually-operated switch 9 is used to short-circuit the lower rated thermostat 7. If the thermostats are in parallel, Fig. 2, the switch 9 is used to disconnect the higher rated thermostat 8 from the circuit. In an alternative arrangement shown in Fig. 5, having two electric heating elements 4 and 4a arranged in parallel and two thermostats 7 and 8 connected in series, a double-pole manually operated switch 9 is adapted in one position to disconnect one of the heating elements 4a from the circuit or, in its other position, to connect the heating element 4a in the circuit and to short-circuit, at the same time, the lower rated thermostat. In all cases the two thermostats may be replaced by a single bipolar thermostat.