Navien Np-210a Condensing Tankless Water Heater with Pump and Buffer Tank, Natural Gas Commerical Series 98 percent thermal efficiency. 0.96 energy factor 17000 - 21000 BTU/hr Flow rates - At 35 Degree Fahrenheit Rise : 12 GPM, At 45 Degree Fahrenheit Rise : 8.4 GPM Easy installation and PVC venting Includes NR-10DU remote control