Abstract: A ventilation system for institutional and commercial cooking equipment includes a hood which is placed over the equipment and which attaches to an exhaust duct and fan that removes a relatively constant volume of air from beneath the hood. A make-up air supply divides to form a fresh air duct that connects to the hood and a tempered air duct which also connects to the hood. The fresh air is directed beneath the hood by fresh air registers and the tempered air is directed into the surrounding room by tempered air registers. The relative amounts of fresh air and tempered air can be changed by a damper, but the damper does not significantly alter the total amount of supplied make-up air. The system can thus be adjusted to use more or less tempered air as various combinations of cooking equipment are used without affecting the overall balance of exhaust air and make-up air.