Control apparatus for gas burning appliance

A control apparatus for a fanned, gaseous fuel-burning appliance which comprises:

• a first gas valve for controlling flow of gas to a lighting jet;
• an electrical ignition means for igniting gas at said jet;
• a main gas burner disposed adjacent said lighting jet;
• a second gas valve for controlling flow of gas to said main burner;
• a first sensor for detecting the existence or non-existence of a flame at said lighting jet;
• a second sensor for detecting the existence or non-existence of a predetermined air flow created by an electrically driven fan means;
• electrical circuitry for initiating a predetermined lighting-up sequence, said first and second sensors comprising, respectively, first and second change over switch means each having a normally-closed pair of contacts and a third, normally open contact;
• and, electromagnetic relay means having a third switch means arranged to close on a demand for heat being indicated to the apparatus, an operating coil serially-connected with a demand-for-heat switch means, said operating coil being serially connected to an electrical supply, a fourth switch means which, upon energization of said operating coil, completes a self-holding circuit, and a fifth switch means to energize said electrically driven fan means, the normally-open contact of the second switch means being connected to the common contact of the first switch means through the third switch means, the normally-closed contacts of the first switch means being connected, upon the passage of electrical current thereto, to actuate the first gas valve and the normally-open contact of the first switch means being connected, upon the passage of electrical current thereto, to actuate the second gas valve.