The proportional automatic combustion control system null in the gas boiler

摘要

PURPOSE:To reduce a gas pressure set value R and to prevent the occurrence of overshoot and undershoot of a gas pressure during the change of a combustion state by a method wherein an orifice mechanism comprising primary and secondary orifices is located right after a proportional gas valve and an orifice is located in a burner duct. CONSTITUTION:An air pressure PA in a burner duct 1 at a first air pressure detecting point 20 is guided to the one chamber 14a of an air pressure diaphragm 14 through a first pressure detecting piping 16, and a gas pressure PG at a gas pressure detecting point 21 at a gas flow passage 5 is guided to a gas pressure diaphragm 15 through a second pressure detecting piping 17. Meanwhile, an air pressure PW at a second air pressure detecting point 22 is guided to the other chamber 14b of the air pressure diaphragm 14 through a third pressure detecting piping 18. In relation to a gas flow passage 5, an orifice mechanism 23 comprising primary and secondary orifices 23A and 23B is located in the downstream position of a proportional gas valve 6. Further, an orifice 24 serving as a means to cause incurring of a pressure loss is arranged on the downstream side of the first air pressure detecting point 20 in the burner duct 1.