Profile: Cambridge Engineering, Inc. manufactures energy efficient heating and ventilating systems for warehouses, distribution centers, manufacturing plants, automotive service facilities, parking garages, indoor sports facilities, restaurants, and commercial/industrial buildings. Our S-series heater utilizes 100% fresh air to dilute contaminants generated within the building. Our S-Series Blow-Thru™ space heaters are used to solve negative air pressure problems and eliminate cold drafts from open dock door. Our M-series make-up air heaters feature variable air volume system with optional VFD (Variable Frequency Drive) controls to provide energy compensation for varying amounts of exhausted air.