GB1394204A - Tubular temperature sensors in direct fired water heaters - Google Patents

Abstract

1394204 Valves A O SMITH CORP 12 July 1972 [12 July 1971 21 April 1972] 32666/72 Heading F2V [Also in Division F4] A temperature-controlled valve suitable for the water inlet of a water heater comprises an outer tube 6 so secured to an inner tube 5 as to contain at least part of the inner tube, one of the tubes having a higher coefficient of thermal expansion than the other tube and being free to expand longitudinally relative to the other tube in response to an increase in temperature, at least one of the tubes being provided with at least one aperture 10, 11, adjacent one end thereof, the arrangement being such that a passage for water between the interior of the inner tube 5 and the exterior of the outer tube 6 by way of the aperture or apertures 10, 11 is substantially closed below a predetermined temperature and open above a predetermined temperature. In the embodiment shown, the inner tube 5 of stainless steel is attached to an inlet fitting 3 at the top of the water heater (1), Fig. 1 (not shown) and the outer tube 6 of plastics material, e.g. polypropylene, is secured by means of screws 8 to the lower end of the tube 5 and is free at its upper end. When the temperature of the water in the upper region of the heater (1) exceeds a predetermined value, cold water, which is normally discharged from the dip tube via apertures 9, is also discharged through apertures 10 and 11 which are in partial registration, Fig. 3 (not shown). In an alternative embodiment, Fig. 5 (not shown), expansion of the outer plastics tube 14, which is secured at its top end to a fitting 15, causes the inner tube to be drawn away from a sealing face 19 of the fitting. As a result, a Venturi nozzle is formed and incoming cold water entrains hot water from the upper region of the heater and discharges it from the lower end of the tube.