A cyclic flow valve (20) for cyclically controlling the flow of combustants into a combustion furnace. The cyclic flow valve includes a valve housing (26) having a chamber (30), an inlet (36), and an outlet (46). The cyclic flow valve also includes an aperture plate (52) rigidly fixed within the chamber of the valve housing. The aperture plate has first and second apertures (68a and 68b) extending through the plate. A rotor member (54) is rotatably secured within the chamber. The rotor member is held in spaced disposition from the aperture plate. The space defines a low flow gap (92) of predetermined width between the rotor member (54) and the aperture plate (52). The rotor has diametrically opposed paddles (70s and 70b) positioned and sized to selectively control the flow of combustants through the flow valve between a low flow position, wherein the combustants flow through the low flow gap at a predetermined minimal flow rate, and a high flow position, wherein the combustants flow between the inlet and outlet at a predetermined maximum flow rate. In the low flow position, the paddles (70a and 70b) obstruct flow through apertures (68a and 68b) in the aperture plate (52). In the high flow position, the paddles do not obstruct flow through the apertures. The cyclic flow valve includes a rotary motor (50) for rotating the rotor member (54) within the chamber between the low flow position and high flow position.