How to use a Stiebel Eltron water heater
Updated: 17.10.2026
If you are learning how to use a Stiebel Eltron water heater, identify the model. A display DCE-X, a rotary DCE-S and the 10 litre SNU do not share controls. On a commissioned DCE you select an outlet temperature and open the hot tap. On an SNU the store must already have been filled through its open-vented tap before power is applied. The [main Stiebel Eltron comparison](/hub/hot-water/stiebel-eltron-water-heater) names all four models. Peter F. checked the maker’s instructions and the UK listings, not a lab. A qualifying purchase can earn a commission at no extra cost to you.
If you are learning how to use a Stiebel Eltron water heater, identify the model. A display DCE-X, a rotary DCE-S and the 10 litre SNU do not share controls.
If you are learning how to use a Stiebel Eltron water heater, identify the model. A display DCE-X, a rotary DCE-S and the 10 litre SNU do not share controls. On a commissioned DCE you select an outlet temperature and open the hot tap. On an SNU the store must already have been filled through its open-vented tap before power is applied. The main Stiebel Eltron comparison names all four models. Peter F. checked the maker’s instructions and the UK listings, not a lab. A qualifying purchase can earn a commission at no extra cost to you.
Our top picks
| Badge | Product | Control | Temperature | First step | Note | Price | Offer |
|---|---|---|---|---|---|---|---|
| Best overall |  Stiebel Eltron Stiebel Eltron SNU 10 Plus (GB) | Rotary selector | 35–85 °C | Fill through the open tap first | 10.0 | about £160.68 | View offer |
 Stiebel Eltron Stiebel Eltron DCE-X 10/12 Premium | 4i display, memory, ECO | 20–60 °C, 0.5 °C steps | Set temperature, then open the tap | 8.8 | about £412.86 | View offer | |
| Preis-Tipp |  Stiebel Eltron Stiebel Eltron DCE-S 10/12 Plus | 3i rotary selector | 20–60 °C listed | Turn the dial, then open the tap | 7.6 | about £327.61 | View offer |
On this page
DCE-X: display, memory and ECO
The DCE-X Premium heats only while enough water is flowing. Set the temperature, then open the hot tap. It switches on above roughly 1.3 litres a minute and off when the tap closes. The selector runs from 20 to 60 °C in 0.5 °C steps, up to the installer’s ceiling.
To store a temperature, hold memory key 1 or 2 for more than three seconds until the display flashes once. The manual suggests about 38 °C for a shower and 55 °C for a kitchen sink.
ECO limits flow, not power. Hold “i” for more than five seconds until “P 1” appears, press “i”, then turn the selector. ECO1 is 6 litres a minute, ECO2 is 5 and ECO3 is 4. OFF removes the limit. A lower flow can help hold temperature. It does not turn a 6/8 into a 10/12. Rise and inlet temperature are in the shower guide.
DCE-S: use the rotary selector
The DCE-S 10/12 Plus uses a rotary selector, not the Premium display. Turn it within the listed 20–60 °C range, open the hot tap and let the outlet settle. There is no memory key and no ECO menu. Holding “i” applies only to the DCE-X.
Do not open the case to chase a temperature. The installer sets the load and the anti-scald steps of 43, 50 or 55 °C. Above 43 °C, scalding matters, especially for children. For a shower, the contractor must cap the range at 55 °C or less. That ceiling is separate from a bath mixing valve. If you are still choosing the control type, use the buying guide.
SNU 10 Plus: fill first and keep the vent open
The SNU 10 Plus (GB) is a 10 litre undersink store for one vertical draw-off. Before first power-up, open the cold inlet and run the hot side of the correct non-pressurised tap until the water is free of air. Switching on an empty store can damage it.
Then use the rotary control within 35–85 °C. A hotter store raises scald risk and standing loss. A cooler store gives less mixed hot water. About 0.31 kWh per 24 hours at 65 °C is a test figure, not a promised bill saving.
Keep the matching three-pipe open tap. Expansion water needs that route while the store heats. A standard mixer or a cap closes the vent. The listing’s 10 litres a minute is store flow, not a DCE’s heated flow. After the hot volume is used, wait for the 2 kW element to reheat.
Where you stop and the contractor starts
Use the external controls only after installation and commissioning. Do not remove the cover, move load-selection parts, alter protection or wire a DCE yourself. It needs permanent wiring, earthing and an all-pole isolator with at least 3 mm contact separation. A qualified contractor installs, commissions, maintains and repairs it, and sets the anti-scald ceiling, including 55 °C or less when a DCE serves a shower. Your own cap cannot exceed that ceiling.
Do not fit a normal mixer to an SNU or add a valve that closes its open outlet. Stop if the case distorts, a breaker keeps tripping, water leaks from the appliance rather than the expected tap route, or an SNU outlet has been capped. Isolate it only as explained at handover. Do not keep resetting protection, and do not heat an empty store to see if the fault clears.
Common questions
How do I save a temperature on a DCE-X?
Select the required temperature, then hold memory key 1 or 2 for more than three seconds. The display flashes once when the setting has been saved. The stored value remains subject to the upper temperature limit configured by the qualified installer.
What do ECO1, ECO2 and ECO3 change?
They cap water flow, not electrical output. ECO1 limits flow to 6 litres a minute, ECO2 to 5 and ECO3 to 4. OFF removes that ECO limit. A lower flow may help maintain temperature, but it does not turn a 6/8 unit into a 10/12.
How do I control a DCE-S without a display?
Use its rotary selector within the listed 20–60 °C range, then open the hot tap and allow the outlet to stabilise. It has no DCE-X memory or ECO menu. If the desired temperature cannot be maintained, ask the installer to check sizing and commissioning rather than opening the case.
Must the SNU be full before it is switched on?
Yes. Open the cold supply and run the hot side of the correct open-vented tap until the water is free of air before power is applied. Initial filling can take several minutes. Switching on an empty storage heater risks damage and is not a user shortcut.
Can I fit a normal mixer to the SNU?
No. The SNU 10 Plus (GB) is non-pressurised and relies on its compatible open tap as the expansion route. A normal mixer can close that route. Use the specified tap arrangement and have any plumbing change made by someone competent with open-vented stores.
When should I call a contractor?
Call one for installation, commissioning, wiring, connected-load selection, internal temperature limits, repairs, repeated breaker trips, case distortion or leakage from an unexpected point. A qualified contractor must also set a shower-serving DCE to a maximum range of 55 °C or less.
Related pages
Sources
Manufacturer pages, UK public sources and the amazon.co.uk listings in this comparison, retrieved on 17 October 2026.
- Stiebel Eltron DCE-X 10/12 Premium (retrieved 17 October 2026)
- Stiebel Eltron DCE-X instruction and installation manual (retrieved 17 October 2026)
- Stiebel Eltron DCE-S 10/12 Plus (retrieved 17 October 2026)
- Stiebel Eltron SNU 10 Plus (GB) technical data (retrieved 17 October 2026)
- Water Supply (Water Fittings) Regulations 1999, Schedule 2 (retrieved 17 October 2026)
- Approved Document G (England) (retrieved 17 October 2026)
- HSE: hot and cold water systems (retrieved 17 October 2026)
- IET: Part P in England and Wales (retrieved 17 October 2026)