3-Phase Electric Tankless Water Heater Wiring

All of the Stiebel Eltron Tempra and Tempra plus series electric tankless water heaters are designed to use single phase power, but they can be wired with 208 V 3-phase if your installation requires it. Two element units including the Tempra 12/12 Plus, 15/15 Plus, 20/20 Plus, and 24/24 Plus will be unbalanced 3 phase. Larger three element units including the Tempra 29/29 Plus and 36/36 Plus will be balanced three phase.

Each circuit should be connected to the 3-phase power source as shown in these diagrams. The number and size of circuit breakers for each model can be found in the Installation Manual

Tempra 29/29+, 36/36+
3-phase wiring diagram


Balanced 208 V 3-phase wiring diagram
for Tempra 29/29 Plus and Tempra 36, 36 Plus.

Tempra 15/15+, 20/20+, 24/24+
3-phase wiring diagram


Unbalanced 208 V 3-phase wiring diagram
for Tempra 15/15 Plus, 20/20 Plus, and Tempra 24/24 Plus

Tempra 12/12+
3-phase wiring diagram


Unbalanced 208 V 3-phase wiring diagram
for Tempra 12/12 Plus