WATER QUALITY TESTING

While geothermal loop systems are constructed with high density polyethylene (HDPE) pipe, they are typically connected to either copper or steel pipe inside a building. The fluid circulating through the system is either water or a water/antifreeze solution. Since either fluid circulating through copper or steel pipe will produce corrosion or scale over time, it is important to monitor the loop fluid chemistry and make adjustments as necessary to ensure problem free operation.

Water quality testing allows the loop fluid to be evaluated for levels of iron, silica, corrosion inhibitors, acidity and alkalinity (pH levels) as well as water hardness. Additional testing can also be performed to determine if iron bacteria is present in a closed loop system. Iron bacteria can produce a host of operational issues including clogged heat exchangers and pumping problems.

While initial commissioning of a geothermal loop system can eliminate most problems, regular water quality testing is critical to the long term operating efficiency of the system.

Antifreeze Testing

Antifreeze solutions are commonly used in geothermal heat pump systems since loop temperatures can approach or even dip below freezing while providing heating during the winter months. The most commonly used antifreeze solutions in closed loop geothermal heat pump systems are propylene glycol and ethanol. Both environmentally friendly antifreeze solutions are approved for use in these systems by the New Jersey Department of Environmental Protection. Like the antifreeze in your car, if antifreeze is installed in a geothermal loop system it needs to be monitored, tested and adjusted at regular intervals.

However, these two different fluids require different testing methods in order to determine if the required level of freeze protection is being provided. Propylene glycol is tested using an instrument called a refractometer, while ethanol can be tested with a hygrometer. Antifreeze levels can be evaluated at the same time water quality testing is completed and should be incorporated into a comprehensive maintenance plan.