Navien Np-180a Condensing Tankless Water Heater with Pump and Buffer Tank, Natural Gas Commerical Series 98 percent thermal efficiency. 0.96 energy factor 17000 - 199000 BTU/hr Flow rates - At 35 Degree Fahrenheit Rise : 10 GPM, At 45 Degree Fahrenheit Rise : 7.7 GPM Easy installation and PVC venting Includes NR-10DU remote control