Bosch Tankless Gas Water Heater, Series: Therm, 225000 Btu/hr Heating, Liquid Propane Fuel, 3/4 in NPT Gas Connection, Spark Ignition, Direct Vent, Condensing/Non condensing: Condensing, 0.5 gpm, 329 gph Recovery Rate, 0.98, Wall Mounting, 3/4 in NPT Water Connection, 30 to 150 psi, 100 to 140 deg F, Ultra Low Nox: No, Indoor/Outdoor: Indoor/Outdoor, 17-7/8 in W x 11-1/4 in D x 30-1/2 in H, Commercial/Residential/Dual: Commercial/Residential, Import

This is the highest performance, fully condensing gas tankless water heater from Bosch. Unlike traditional non-condensing models, condensing technology captures heat from the exhaust gas and uses it to preheat the incoming cold water. This increases efficiency and reduces emissions - well ahead of the 2012 Low NOX emissions standards set by SCAQMD (California's South Coast Air Quality Management District).