Natural gas tankless water heater, maximum 199,000 BTU for up to 3 major appliances or 3 showers at a time. ENERGY STAR qualified. Indoor installation only. Scale reduction software, freeze protection, and multiple safety features. Weight: 59 Lb. Rated up to 10,100 feet elevation. Requires 3/4 In. gas line. Easy installation schedule 40 PVC venting system. High efficient condensing model. Energy factor: 0.95. Units must vent independently and with approved venting materials. Optional concentric vent kit available. 12 year limited warranty on heat exchanger. 5 year limited warranty on parts. Tankless Water Heater Valve Set available, designed to simplify the installation, maintenance, and operation of tankless water heaters. Unit meets California Air Quality Management District Ultra-Low NOx rules.