Abstract: Combustion air under pressure directed horizontally in a fan shaped jet against hogged fuel dropping in a free fall trajectory from a feed chute toward the furnace grate spreads the fuel across the length and width of the grate more effectively than in prior art air jet dispersers. Increased combustion efficiency and heating capacity are achieved from use of tandem oscillating flow restrictor gates in the jet nozzle duct, one such gate being oscillated at twice the frequency of the other and with additive effects on resultant variations in jet air discharge velocity.