Fuel gas is fed directly into the make-up air burner. The air stream's kinetic energy furnishes combustion air. It functions properly at the velocity and pressures associated with usual ventilating systems.

The burner operation: the combination of velocity impact and suction generated by the combustion-baffles shape induces air through the ports into the combustion zone. The air supply is constant, though only mixes with the gas flowing into the burner ports. When a very small quantity of gas is admitted to the burner, sufficient air to gas mixing takes place in the low-fire slot within the burner casting. Combustion takes place in this zone. Since the burner casting contains the low-fire zone, the casting shields the flame from uncontrolled air entry.

Increasing gas supply moves the flame out to the intermediate fire zone for additional air. At full capacity, mixing occurs at the larger air ports of the high-fire zone, enhanced by air spilling over the end of the baffles. Reducing the gas supply reverses the sequence - flame recedes to the air-supply location until the low-fire zone is reached.