Heater with flame powered logic supply circuit

Abstract

A flame powered logic supply circuit (60) responds to a pilot flame (39b) and supplies electrical energy to power electronic logic circuitry (62) for a heater, such as a hot water heater (1), a furnace, or the like. A thermoelectric element (64) responds to the flame and outputs electrical current which is stored in an inductor (70). A pair of parallel circuit branches (78 and 80) are connected to the thermoelectric element (64) and the inductor (70). The first branch (78) has a semiconductor switch (82) with an on state during which current flow supplies energy to the inductor (70) which is stored therein. The second circuit branch (80) has a second energy storage component provided by a battery (90) which receives the stored energy from the inductor (70) during an off state of the semiconductor switch (82) to charge the battery (90) and maintain a given power rating thereof for powering electronic logic circuitry (62) of the heater. Monitoring circuitry is provided by a current sensing resistor (74) and a comparator (96) controlling the semiconductor switch (82) between its on and off states. Circuits (60, 60a) may be provided for both the pilot flame (39b) and a main burner flame (10a), or only for one or the other. The circuits (60, 60a) include indicia (94, 94a) providing a display indicating that each respective flame is lit and that energy is being supplied therefrom for powering the logic circuitry (62).