Overview: This case study reviews the performance of CambridgeŽ direct gas-fired make-up air heaters providing tempered make-up air for restaurant kitchen applications. The requirements that had to be addressed by the Cambridge make-up air heaters installed at various restaurants located through out U.S and Canada are listed, illustrating the various system components and their functions. System's capabilities in overcoming indoor air quality problems and minimizing operating costs, as well as its certifications meeting latest safety standards are also highlighted. A list of satisfied users of Cambridge make-up air heaters and ventilation equipment for restaurant and commercial kitchen applications is also provided.