The application of controls for HVAC systems in industrial buildings has always posed a problem of reliability and service. Commercial-grade controls have not always stood up well in a rugged working environment nor is maintenance prioritized over that for the production process. industrial-grade controllers, on the other hand, offer a high degree of accuracy and reliability but have proven difficult to justify economically. The emerging predominance of programmable logic controllers in industrial processes offers an excellent opportunity to extend this fine technology into HVAC system control This same system cart provide plant-wide facilities monitoring and management, utilizing a common communications network shared with that of the process. At the same time, the full benefits of common system elements and operations enhance overall system reliability and maintenance.

This paper addresses an example of the use of programmable logic controllers for HVAC control in an automotive parts manufacturing and assembly building in Battle Creek, MI. The plant, built in two phases, occupies just over I million ft 2 and produces radiator, condenser coil, and heater assemblies for the automotive industry.

This paper describes the system application together with relative merits of programmable logic controllers vs. more conventional pneumatic or direct digit control systems. Methods of signal and control interface are described together with programming logic, communications protocol, and facilities monitoring capability. As with arty other primary control system, the importance of system checkout and commissioning is emphasized together with operator training.