Bosch AquaStar Propane Tankless Water Heater #125HX-LP 4.3 GPM tankless water heater provides heat on demand Can cut water-heating costs by up to 50 percent Uses propane gas; temperature control with modulating gas valve Designed to vent vertically Measures 29-3/4-by-18-1/4-by-8-3/4 inches; weighs 40 pounds; 12-year limited heat exchanger warranty, 2-year limited parts warranty