The apparatus suitable for all primary-air burning type gas- fired water heater, comprises a combusting section having a combustion chamber for burning fuel gas mixed with primary air and an exhaust discharging way with a noise reduction means; a supplying section for forcedly supplying primary-air and fuel gas to the chamber and mixing them, the section having a plate for closing primary air suction inlet; a combustion plate for dividing the combusting section from the supplying section. Fine control means for reducing pulsating combustion generated from the noise reduction means, is mounted on the primary-air suction inlet.
