Unlike any other heating and cooling system, a geothermal heat pump can preheat your hot water. This means sometimes you will use little or no additional energy to heat water. A device called a "desuperheater" transfers excess heat from the pump to the water heater. In the summer, hot water is provided with no additional energy usage and in the winter, water heating costs are cut roughly in half. Your HVAC contractor can tell you if this process will work with your water heater.
