Advanced design, high-quality materials, reliable hot water. The Hubbell Synergy Hydro Transflow is our indirect fired water heater for light duty applications. It generates domestic potable water with an existing supply of boiler water. Heavy duty construction, even in our light duty models, with a HydraStone™ cement lined tank and copper silicon tappings that resist corrosion. Heavy gauge copper fin tube coil provides maximum heat transfer. High-efficiency water heating with 2” thick polyurethane foam insulation. No moving parts and no electrical connections required.