Control system for dual coil pilot valve burner system

An ignition and control system for ignition of fuel discharged from a burner assembly including a main fuel burner having a fuel supply line connected thereto, a pilot burner to ignite fuel discharged from said main burner, and a pilot fuel supply line extending to said pilot burner, said system comprising:

• ignition means to ignite fuel discharged from said pilot burner;
• a normally closed main gas valve and an electromagnetic main coil energizable to open said main gas valve;
• a normally closed pilot gas valve and electromagnetic pick and hold coils energizable to open said pilot gas valve;
• condition sensing switch means for connection in circuit to a voltage source;
• lockout switch means including a lockout switch which in a closed position is in circuit with said condition sensing switch means, and further including heating means in circuit with said condition sensing switch means in said closed position of said lockout switch, said heating means being operative upon prolonged energization of said heating means to move said lockout switch to an open position to open the circuit to said condition sensing switch means, said lockout switch in its closed position being in circuit with said hold coil for energization thereof;
• combustion detection switch means having a cold switch pole, a hot switch pole in circuit with said main coil of said main gas valve, and a combustion detection switch engaging said cold switch pole, in circuit with said lockout switch, and responsive to the presence of a flame at said pilot burner to move from said cold switch pole to said hot switch pole for opening said main burner;
• and
• ignition switch control means including switch actuating means in circuit with said heating means and said cold switch pole, and further including ignition switch means operative upon energization of said switch actuating means to connect said pick coil in circuit with said lockout switch in said closed position of said lockout switch for opening said pilot gas valve in conjunction with said hold coil and for connecting said ignition means in circuit with said lockout switch in said closed position of said lockout switch whereby fuel discharged from said pilot burner can be ignited, the absence of ignition of said fuel discharged from said pilot burner resulting in said prolonged energization of said heating means and movement of said lockout switch to said open position.