GeoStar_Aston-DualSpeed-Hydronic-Unit(300)GeoStar. Aston dual-speed geothermal hydronic heat pumps are available in 8- and 15-ton capacities, providing radiant floor heating, pool heating, and snow and ice melt to homes with high-volume water demands. The steel hydronic cabinets feature a microprocessor to control the unit’s pumps and compressor with thermostatic inputs. The IntelliStart feature reduces the amount of current needed to start the unit by 70%, alleviating light flicker, reducing start-up noise, and increasing compressor life, claims the manufacturer. 800.436.7283.