Question: what is the best residential tankless water heater?
Answer: Rinnai RUR98iN (Top Overall) ... 
Rinnai RUC98iN (Indoor) ... 
Rheem RTG-84XLN (Outdoor) ... 
Rheem RTGH-95XLN (Best Outdoor) ... 
Takagi T-KJr2 IN-NG (Indoor) ... 
Stiebel Eltron Tempra Plus 24 (Best Electric) ... 
Eemax EEM24027 (Electric) ... 
EcoSmart ECO 27 (Electric)