Patent GB-606538-A (GB)
Title: Hot water boiler
IPC: F24H1/36
Filed: 1945-12-11
Abstract: 606,538. Water-heating stoves; gas burners. EXPERIMENTAL LABORATORIES, Inc. Dec. 11, 1945, No. 33535. Convention date, Jan, 12. [Classes 75(i) and 126] [Also in Group XIII] A water boiler comprises a water container 10, an associated fire chamber 11, a burner with openings to deliver gaseous fuel and air in pre-determined proportions with a minimum excess of combustion air into the fire-chamber, an outlet flue 16, 16a, through which the flue gases are drawn by controllable suction means, e.g. a fan 15, to the atmosphere, and an air port 113 in the flue between the fire chamber and the suction means to admit air to dilute the flue gases and so prevent condensation in the outlet flue. The burner comprises a dished plate 58 and a plate 60 supported on and spaced from the plate 58 so as to form narrow passages leading from the outlet of the fuel supply pipe 62 to the periphery of the plate 60. Air for combustion is drawn through openings 20, 21, 22 in the plate 58 and, if desired, through an opening 86 in a plug in the pipe 62. the ratio between the combined cross-sectional areas of these openings to an opening in a partition 84 in the gas supply pipe is such that the air supplied for combustion is only slightly in excess of that necessary for complete combustion. Gaseous fuel is supplied to the burner through valves 63, 64 which are operated by diaphragms 72, 66 which curve in response to changes in the vacuum produced by the fan respectively on the suction side of the fan and in the fire chamber. The chambers 67, 74 on the upper sides of the diaphragms 66, 72 are connected respectively to the intake side of the fan, by a pipe 70 and to the pipe 62 on the burner side of the valve 63. When the temperature in the water chamber 10 rises above a predetermined level which is slightly above that at which condensation in the tubes 18 would set in, a thermally actuated switch cuts off the current to the fan motor, and restores it when the temperature falls below that level. A pilot burner adjacent to the main burner heats an associated thermocouple operating an electromagnet controlling an electric switch in the fan motor circuit, so that if the pilot burner is extinguished, the fan stops. The pilot burner is also adjacent to the firedoor which is pivoted so as to swing open when there is no vacuum in the fire chamber, so as to supply air to the pilot burner. Flue tubes 18 arranged in a ring lead through the water chamber from the fire chamber 11 to a smoke box 17, from which a flue tube in two parts 16, 16a leads downwardly to the fan 15 and thence to the outlet flue 23. Air is supplied to an opening 113 between the tube parts 16, 16a through a pipe 111 which surrounds the part 16a and extends through the fire chamber. The flue tubes 18 contain V-shaped baffles 35 which are supported on rods 32 with spacers 33 which, by pressing on the limbs of the baffles when the nuts 38 are tightened, force the curved edges of the baffles into close contact with the tubes. The top 26 of the smoke box 17 is removable when the insulating cover 47 is removed, to enable the baffles to be removed for cleaning.