Excessive temperatures while heat exchanger was scaled. Equipment was cleaned prior to installation of system in February 1996. Six month inspection revealed no scale formation. Cleaning required only flushing bottom with garden hose and took only a few minutes. Installed January 96, inspected June 96 and boilers were spotless.
Gate valves and check valves scaled to the point of in-operation.
All symptoms of hard water scale since installation have been eliminated. Upon inspection of boiler, boiler was found to be free of any scale accumulation.