Patent GB-1313602-A (GB)
Title: Gas fired fluid heater
IPC: F24H3/08
Filed: 1970-06-09
Abstract: 1313602 Gas-fired fluid heater GAZ DE FRANCE 9 June 1970 [9 June 1969] 27980/70 Headings F4A and F4T In a gas-fired water heater or other fluid heater including at least one burner 14 in a chamber 2, a heat exchanger 4 in a fluid reservoir 5, an air inlet pipe-line 3 and an outlet pipe-line 13 from exchanger 4, connected to a flue, the boiler has a mechanical extractor 12 in pipe-line 13, a thermostat 33 in the reservoir 5 and a sparking plug 37 for ignition, and a control system is provided including a first valve in the burner gas supply sensitive to pressure in the outlet and a second valve in the gas supply operable by a heat sensitive element adjacent the burner, which may be a main or pilot burner. The exchanger 4 comprises hollow fins 7 circumferentially spaced in a ring about a central chimney 8 and opening thereinto, aspiration pipe-line with adjustable orifice 10 and throttle 22 connecting chimney 8 to base 11, housing fume extractor 12, e.g. a ventilator or turbine, and outlet pipe-line 13 coaxial with pipe-line 3, thus allowing preheating of combustion air. Gas is supplied to main burner 14 and pilot light 15 by pipe-line 16 in which the first valve in the form of differential pressure sensitive capsule 18 is situated, the capsule 18 having membrane 25 defining chambers 17 and 20 such that the pressure applied across the membrane may effect control of the valve. A ternatively capsule 18, as in Fig.4 (not shown), may comprise three chambers (60), (61), (62), the difference in pressure between the atmosphere and pipe-line 9 controlling the valve. A bimetallic strip or other heat sensitive element 26 is placed adjacent pilot light 15 and controls the second valve by means of lever 30, but the pilot light 15 may be dispensed with in which case element 26 is placed adjacent main burner 14 and controls valve 31 via solenoid 32. When water 6 is to be heated, thermostat 33 applies a potential to drive motor 34 of ventilator 12 and to transformer 35, to the primary of which is connected delay device 36 and to the secondary sparking plug 37. Thermostat is connected to contacts 47, 48, 53 and 55 capable of respectively controlling lead 46 of delay device 36 and solenoid 32, supply leads 49 and 52 of motor 34, and lead 56 of a solenoid 57 controlling a third valve 44 to cut off gas flow before motor 34. On demand for heat the contacts are closed to their portions in Fig. 3 and source 45 supplies device 36, solenoid 32 and motor 34 thus opening valve 40 to allow gas to reach burner 14 and be ignited by plug 37, element 26 operating a bolt 43 to hold valve 40 open while a flame exists. As the water temperature rises contacts 47, 48 and 55 are pushed to the right to open, and spring-biased contact 53 is displaced later by element 54, solenoid 50 keeping motor 34 in operation during this time lapse until all contacts are open and gas supply is finally cut-off. In alternative heater constructions as in Figs. 5 and 6 and in Figs. 7-10 (not shown), heat exchanger 4 may comprise several unit elements 104 in rows or in a circle, each having an independent combustion chamber 105 and exchange chamber 106 but being connected to a common inlet and a common exhaust outlet and flue, the internal face of chamber 106 having paired ribs 110.