Roll-out flame detector for swimming pool heater fuel gas control

Claim 1

In a swimming pool heater having a combustion chamber and a control chamber separated by a fire wall having a lower edge, burner tubes extending from the control chamber into the combustion chamber beneath the lower edge, a fluid fuel supply, a control valve connected in fluid communication between the fuel supply and the burner tubes and adapted to be opened and closed to the flow of fluid fuel to the burner tubes, and an electrical control circuit operably connected to the control valve for opening and closing the control valve, a flame detector device, comprising: (a) a base, (b) a pair of electrical contacts, (c) insulated mounting means supporting said electrical contacts at longitudinally spaced positions on said base, (d) an elongated thermal fuse element having opposite ends and adapted to melt at a predetermined termperature substantially less than the temperature of the flame produced by the burner tubes, (e) suspension means holding the opposite ends of said fuse element between, and in electrical communication with, said pair of electrical contacts and spaced from said base, (f) an inextensible linear member extending along said fuse element and having opposite ends connected to said suspension means to prevent stretching of said fuse element, (g) means mounting said base on the fire wall within the control chamber so that said fuse element extends substantially along and proximate to the lower edge of the fire wall, for sensing any roll-out flame from the combustion chamber beneath the fire wall into the control chamber, and (h) means connecting said electrical contacts in said electrical control circuit so that the control valve functions normally while said fuse element is unbroken, but said control valve is closed when said fuse element ruptures.