Stiebel Eltron Tempra Plus whole-house electric tankless (12-36 Plus): quick sheet

Covers: Tempra Plus (and Tempra Trend) 240/208 V whole-house electric tankless heaters; this sheet details the 24, 29 and 36 Plus.

Cross-checkedBrands: Stiebel Eltron3 components

Electronically controlled electric tankless with multiple heating circuits, each on its own double-pole breaker. Huge current draw: the home's service size and wire must match the manual. Common calls: one bank not heating (breaker or element), low flow, scale on the flow sensor screen.

Safety first

Turn off the breaker and verify zero volts before touching elements, thermostats or terminals; 240 V tank and tankless units can be lethal.
Never energize an element without water around it (dry fire).
Do not remove or plug the T&P relief valve; its discharge line must run to a safe spot.
Multiple 240 V circuits: turn off ALL breakers feeding the unit.

How it works

Flow sensor detects demand; the board modulates power to several heating elements to hit the setpoint.

Each element bank has its own supply circuit; losing one breaker cuts capacity.

Components & tests

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OnCall Tech is a reference tool for trained technicians and can make mistakes. Always disconnect power and confirm with the manufacturer's documentation before you work. © 2026 OnCall Tech. Original content; not a reproduction of any manufacturer document.Generic part photos (not of this brand): Two wall-mounted tankless water heaters with expansion tanks on an exterior wall by Downtowngal, CC BY-SA 4.0

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