Water Furnace.  Envision NSW Series geothermal hydronic units are available in 1.5- to 6-ton capacities for versatile hydronic heating. The units can provide heat for domestic hot water, radiant floor heating, pool heating, and snow and ice melt, while reducing hot water costs by as much as 60% a year, the maker says. NSW units also can provide chilled water for cooling applications. The unit’s controller allows the user to view all modes of operation and to easily adjust temperatures. The units feature ThermaShield foam insulation to increase efficiency and consistency of the heat exchangers. Tax credits may be available for geothermal systems. 800.934.5667. www.waterfurnace.com.