Calcium carbonate scale and iron related fouling are the most common water quality problems in the U.S. When hard water is supplied to an open-loop heat pump operating in the cooling mode, or to a desuperheater (in an open- or closed-loop system), scale can occur on the heat exchanger surfaces. This scale can reduce the performance of the heat pump and, in some cases, has rendered desuperheaters inoperable. This paper discusses water chemistry as it relates to scaling along with how this issue impacts geothermal heat pumps. Conditions necessary for the occurrence of, and design strategies to limit, the impact of iron precipitation are also discussed along with treatment methods for iron bacteria.

Units: Dual