The results of this study do not indicate any clear advantage for any of the three devices tested versus a control for the inhibition of mineral scale formation or the corrosion of copper. The test protocol was designed to simulate the method of production of hot water used in many larger institutional type settings that employ a shell and tube heat exchanger for the production of hot water. The findings do not support the claims of the manufacturers regarding the ability of their respective devices prevent mineral scale formation in hot potable water systems. The amount of mineral scale formed for the control versus device heat exchange tubes was relatively constant, and proved to be an effective insulator of heat transfer across the tube surface. The scale formed was found to be a type of calcite (calcium carbonate), and had the same crystalline structure for each heat exchange tube. There was no discernible effect on the crystalline structure of the scale formed by any of the tested devices.