Fuel oil supply circuit for an oil burner having a solenoid valve in parallel circuit with diaphragm valve for controlling oil flow at start up

A fuel oil supply circuit for supplying fuel oil to a nozzle in an oil burner, comprising:

• an oil pump connected to a fuel supply and adapted to provide pressurized fuel oil;
• a regulating valve assembly having an inlet port receiving the pressurized fuel oil and an outlet port connected with the nozzle, the regulating valve assembly having open and closed positions allowing and preventing flow of the pressurized fuel oil between inlet and outlet ports, respectively;
• a solenoid valve controlling flow of pressurized fuel oil through the regulating valve assembly, the solenoid valve having a first state keeping the regulating valve assembly closed and a second state allowing the regulating valve assembly to open;
• and
• a diaphragm valve fluidically connected to the pump in parallel circuit with the regulating piston assembly, the diaphragm valve having a first position allowing flow of pressurized oil through a return to the fuel supply and a second position forcing oil to flow to the regulating valve assembly.