HydroTherm now offers the Model HW100 and Model HV100 series boilers. They are gas-fired, have thicker walls, and up to 30% more cast iron than competitive boilers, allowing for better heat transfer, heat retention and a fuel efficiency rating of up to 84%. Extra-deep 2 ¾” sections allow for increased water content and total water surface, as well as an internal draft diverter to ensure high-efficiency venting and the safe discharge of all combustion products. HV series boilers are available from 50,000 to 150,000 MBH, while the HW series goes up to 200,000 MBH.