GB871333A - Improvements in water heating and hot water supplying apparatus - Google Patents

Abstract

871,333. Electric water heaters. KENDON DEVELOPMENTS Ltd. Aug. 7, 1957 [Aug. 22, 1956], No. 24918/57. Class 39(3). [Also in Group XIII] A cylindrical water container 1, mounted in an outer box 2 containing lagging material 3, has heating means such as an electric heating element 4 attached, e.g. by brazing 4a, to a thermostat pocket 5. An inlet pipe 6, which may include a one-way check valve 7, enters the container 1 at a level just above that of the pocket 5 and extends to the middle of the container 1. An electric solenoid valve 8 is connected to the water supply which is controlled at the desired pressure by a header tank 9 or a pressure reducing valve 10. A back-pressure-opening water control 11 set to close at for example, two lbs. per square inch above atmosphere is also connected to the water supply and by-passes the valve 8, being "teed" into an expansion or vent pipe 12 which has an air bleed hole 13 at the top of the inside of container 1. An outlet pipe 14 has one or more taps 15, and a cock 16 is provided for filling and draining. The element 4 and the solenoid valve 8 are connected in series to the current supply source, and a thermostatically operated switch 5a is connected in parallel with the valve 8. With the switch 5a open the element is inoperative and the solenoid coil fully energised, the valve being then open; with the switch 5a closed, the element is energized and the solenoid coil short-circuited, the valve then being closed. In operation, the container is filled by opening the cock 16, air passing through the hole 13 into the expansion pipe 12. The element 4 is then energized to raise the temperature of the water to the point at which the thermostat is set, e.g. 225‹F., when the switch 5a will open, energizing the solenoid coil to open the valve 8, and switching off the element. At this stage, pressure in the tank will be higher than that of the water supply. On drawing off hot water from the tap 15, the pressure in the container will drop and cold water will enter through the valve 8 and the control valve 11 causing the switch 5a to close, thus energizing the element 4 and closing the valve 8, water continuing to enter in reduced quantities through the valve 11 which will close when the container is full. The water temperature will then rise until the thermostat again operates to switch off the element and open the valve 8. The valve 11 may be omitted, and the pressure in the tank controlled by a pressure switch. A pressure retaining valve 17 (Fig. 2, not shown) may replace the vent pipe 12. When the thermostat is set for a little below atmospheric boiling point the header tank 9 may be arranged with its float controlled level just below the top of the container 1 (Fig. 3, not shown), the expansion pipe being connected to the header tank and having an evaporation trap. Specification 779,749 is referred to.