Closed recirculating systems are used for cooling and heating tasks in buildings. Because their exposure to the atmosphere is limited, these systems do not have some of the problems of open recirculating (cooling tower) systems. Closed recirculating systems, however, do experience problems of corrosion, microbiological growth and fouling. Appropriate chemical and physical treatment can minimize these problems. Closed systems must be adequately monitored to determine treatment needs,
control treatment programs and detect problems.
Keywords: closed cooling, closed heating, hydronic, corrosion, microbiological growth, chemical treatment, monitoring