Where does scaling commonly occur in SHW systems?
Since indirect systems use a high quality, non-scaling fluid in the collector loop, scaling usually occurs only on the potable water side of indirect systems. Also, because the tendency of a water to scale increases as the water’s temperature increases, scaling tends to be worst where the potable water reaches its maximum temperature, which is where the water contacts hot heat transfer surfaces. In direct systems the hot heat transfer surfaces are the collector riser tubes, while in indirect systems the hot heat transfer surfaces are the heat exchanger walls on the potable water side.
