Delivers up to 4.3 Gal per minute .No standing pilot - no electricity needed. 12-year warranty on heat exchanger - 2 years on parts. Saves up to 50% off utility costs. Compact and lightweight. Can simply hang on the wall. Modulating gas valve to control temperature. Pressure relief valve included.Vents with inexpensive and readily available 5 in B Type Galvanized vent pipe.