Question: what is the best whole house electric tankless water heater?
Answer: Stiebel Eltron Tempra 29 Plus. Stiebel Eltron is another recognizable brand that produces some of the best out there. ... 
Ecosmart ECO 36. Ecosmart is one of the best manufacturer of electric tankless water heaters in the world. ... 
Ecosmart ECO 27. ... 
Rheem RTE 13. ... 
Bosch WH27 Tronic.