Control apparatus for gas burners

Claim 1

A system for automatically controlling the gas burner of an emersion heater to maintain the heat level of a liquid-mass at a desired temperature automatically in a tank containing the liquid-mass equipped with an emersion heater, a gas burner in the heater, a gas supply pipe leading to the burner, a normally closed gas valve in the pipe, a blower for flowing air through the heater to supply oxygen and to remove unburned gas and the products of burned gas, an electric motor driving the blower, a motor circuit powering the motor, and an on-off switch in the motor circuit for controlling the motor to activate and deactivate the blower with the blower having a low air pressure area when operating to force air-flow through said heater; said system comprising: an air pressure sensitive device connected with said low air pressure area of the blower, a burner control circuit, a normally open air flow switch in said control circuit operably connected to said pressure sensitive device; an electric spark igniter at the burner, a normally open flame sensor switch at the burner closing in the presence of a flame, a solenoid on the gas valve for opening the gas valve to supply gas to the burner; said pressure sensitive device closing said air flow switch during low pressure conditions during operation of the blower anD allowing said air flow switch to open upon the blower not operating, a normally closed liquid-mass temperature switch in said control circuit, a mass temperature sensitive apparatus in the tank connected to said temperature switch to open said temperature switch when the mass is at a desired temperature and to close said temperature switch when the mass is below the desired temperature, a relay having a coil in said control circuit, said relay having first and second paired normally open contacts, a time release head on said relay holding said contacts closed for a relatively short time when said coil is energized and then allowing said contacts to open, a first sub-circuit on said control circuit including said first contacts of said relay and said igniter, a second sub-circuit on said control circuit including said second contacts of said relay and said solenoid operating said gas valve, a shunt circuit on said control circuit including said flame sensor switch and said solenoid operating said gas valve, and a manual switch in said control circuit for closing and opening said control circuit; upon operation of the blower said air flow switch closing rendering said control circuit operable by said manual switch, in initially establishing a flame with the blower operating and said air flow switch closed, the operator closes said manual switch in said control circuit energizing said coil of said relay closing said first and second relay contacts for a relatively short time period via said timing head to energize said igniter and to energize said solenoid to open said gas valve, upon a flame igniting said flame sensor switch closes said shunt circuit and maintains said gas valve solenoid energized and said gas valve open maintaining gas supply to the flame to heat the liquid-mass after said time release head allows said relay contacts to open; upon a flame maintaining and heating the liquid-mass to the desired temperature, said temperature sensitive apparatus opens said temperature switch opening said control circuit and deenergizing said solenoid whereupon the gas valve closes and deenergizes said coil of said relay allowing said relay to reset; subsequently upon the heat of the mass dropping below the desired temperature, said temperature sensitive apparatus closes said temperature switch to close said control circuit to re-energize said relay whereupon said flame ignition sequence occurs igniting a flame and said flame sensor closes said shunt circuit maintaining said solenoid energized and the gas valve open maintaining the flame; said foregoing sequences controlled by said heat sensitive apparatus repeating automatically in a cycle to maintain the mass at the desired temperature.

Claim 2

A system for automatically controlling the gas burner of an emersion heater to maintain the heat level of a liquid-mass at a desired temperature automatically in a tank containing the liquid-mass equipped with an emersion heater, a gas burner in the heater, a gas supply pipe leading to the burner, a normally closed gas valve in the pipe, a blower for flowing air through the heater to supply oxygen and to remove unburned gas and the products of burned gas, an electric motor driving the blower, a motor circuit powering the motor, and an on-off switch in the motor circuit for controlling the motor to activate and deactivate the blower with the blower having a low air pressure area when operating to force air-flow through said heater; said system comprising: an air pressure sensitive device connected with said low air pressure area of the blower, a burner control circuit, a normally open air flow switch in said control circuit operably connected to said pressure sensitive device; an electric spark igniter at the burner, a normally open flame sensor switch at the burner closing in the presence of a flame, a solenoid on the gas valve for opening the gas valve to supply gas to the burner; said pressure sensitive device closing said air flow switch during low pressure conditions during operation of the blower anD allowing said air flow switch to open upon the blower not operating, a normally closed liquid-mass temperature switch in said control circuit, a mass temperature sensitive apparatus in the tank connected to said temperature switch to open said temperature switch when the mass is at a desired temperature and to close said temperature switch when the mass is below the desired temperature, a relay having a coil in said control circuit, said relay having first and second paired normally open contacts, a time release head on said relay holding said contacts closed for a relatively short time when said coil is energized and then allowing said contacts to open, a first sub-circuit on said control circuit including said first contacts of said relay and said igniter, a second sub-circuit on said control circuit including said second contacts of said relay and said solenoid operating said gas valve, a shunt circuit on said control circuit including said flame sensor switch and said solenoid operating said gas valve, and a manual switch in said control circuit for closing and opening said control circuit; upon operation of the blower said air flow switch closing rendering said control circuit operable by said manual switch, in initially establishing a flame with the blower operating and said air flow switch closed, the operator closes said manual switch in said control circuit energizing said coil of said relay closing said first and second relay contacts for a relatively short time period via said timing head to energize said igniter and to energize said solenoid to open said gas valve, upon a flame igniting said flame sensor switch closes said shunt circuit and maintains said gas valve solenoid energized and said gas valve open maintaining gas supply to the flame to heat the liquid-mass after said time release head allows said relay contacts to open; upon a flame maintaining and heating the liquid-mass to the desired temperature, said temperature sensitive apparatus opens said temperature switch opening said control circuit and deenergizing said solenoid whereupon the gas valve closes and deenergizes said coil of said relay allowing said relay to reset; subsequently upon the heat of the mass dropping below the desired temperature, said temperature sensitive apparatus closes said temperature switch to close said control circuit to re-energize said relay whereupon said flame ignition sequence occurs igniting a flame and said flame sensor closes said shunt circuit maintaining said solenoid energized and the gas valve open maintaining the flame; said foregoing sequences controlled by said heat sensitive apparatus repeating automatically in a cycle to maintain the mass at the desired temperature.