Gas burner control system

In a gas burner ignition and control system for gas fired apparatus having

• a combustion chamber with a main gas burner and an exhaust vent;
• an electrically operated exhaust blower connected to the vent for drawing ambient air into the combustion chamber and for discharging air and combustion products from the combustion chamber to the atmosphere;
• gas supply control apparatus having a diaphragm operated main valve for connecting said main burner to a source of gas when an operating gas pressure is supplied to the diaphragm operator of the main valve;
• said control apparatus having gas bleed path means for supplying an operating pressure to said diaphragm operator and a servo pressure regulator valve connected in the bleed path means responsive to outlet pressure from the main valve for effecting regulating movement of the main valve;
• main burner ignition means including a pivot burner for igniting gas flowing from the main burner and electrically energizable pilot burner ignition means for igniting gas flowing from the pilot burner;
• and
• flame sensing means including a flame sensor responsive to the presence or absence of flame at the pilot burner and electric switching means operable by the flame sensor to have a conductive condition in the presence of flame at the pilot burner and a non-conductive condition in the absence of flame at the pilot burner;
• the improvement comprising:
• electrical circuit means completed through said electric switching means when in the conductive condition thereof for rendering said exhaust blower operative only in the presence of flame at the pilot burner;
• and
• pneumatically operated bleed valve means connected in the bleed path means and controlling the supply of gas operating pressure to said diaphragm operator;
• said bleed valve means comprising pneumatic actuating means in fluid communication with said exhaust vent and subject to fluid pressure in said exhaust vent for operating said bleed valve means to supply an operating pressure to said diaphragm operator effective to open said main valve only when the fluid pressure in said exhaust vent drops below a predetermined subatmospheric pressure level as a result of the initiation of blower operation by said electrical circuit means in response to the establishment of flame at the pilot burner.

In a gas burner ignition and control system for gas fired apparatus having

• a combustion chamber with an exhaust vent;
• an electrically operated exhaust blower connected to the vent for drawing ambient air into the combustion chamber and for discharging air and combustion products from the combustion chamber to the atmosphere;
• a main burner within the combustion chamber;
• a pilot burner for igniting gas flowing from the main burner;
• gas supply control apparatus comprising a housing having an inlet for connection with a gas supply, a main outlet for connection with the main burner, a pilot outlet for connection with the pilot burner, and a main gas passageway connecting said inlet and said main outlet;
• a first electrically controlled valve in said main gas passageway;
• a biased closed main valve in said main gas passageway downstream from said first valve;
• a pilot flow passage extending from said main gas passageway at a point betweeen said first valve and said main valve to said pilot outlet;
• diaphragm means operatively connected to said main valve for moving the same between on-off positions and regulating positions;
• gas bleed path means in said housing for supplying an operating pressure on said diaphragm means;
• a servo pressure regulator valve connected in the bleed path means and responsive to outlet pressure from the main valve to regulate the operating pressure on said diaphragm means for effecting regulating movement of said main valve;
• electrically energizable ignition for igniting gas flowing from the pilot burner;
• and
• flame sensing means including a flame sensor responsive to the presence or absence of flame at the pilot burner and electric switching means operable by the flame sensor to have a conductive condition in the presence of flame at the pilot burner and a non-conductive condition in the absence of flame at the pilot burner;
• the improvement comprising:
• electrical circuit means completed through said electric switching means when in the conductive condition thereof for rendering said exhaust blower operative only in the presence of flame at the pilot burner;
• bleed valve means connected in said bleed path means and operable independently of said pressure servo regulator valve;
• said bleed valve means having closed and open positions controlling the operating pressure on said diaphragm means to respectively prevent and permit opening of said main valve;
• a pneumatic actuator having an expansible chamber in fluid communication with said exhaust vent and subject to fluid pressure in said exhaust vent;
• and
• said expansible chamber being operatively connected to said bleed valve means for moving the same between said closed and open positions;
• said expansible chamber effecting the opening of said bleed valve means when the fluid pressure in said exhaust vent drops below a first predetermined subatmospheric pressure level and effecting the closing of said bleed valve means when the fluid pressure in said exhaust vent rises above said first pressure level to a second predetermined subatmospheric pressure level which is greater than said first pressure level.