Question: what is the best whole house tankless water heater?
Answer: EcoSmart ECO 27 Electric Tankless Water Heater. ...  Stiebel Eltron Tempra Plus 24 kW Tankless Water Heater. ...  Rinnai RL94eP Propane Tankless Water Heater. ...  Rheem RTG-95XLN 9.5 GPM Low NOx Outdoor Tankless Natural Gas Water Heater.