- Boilers
- Electric water heater
11
Ariston 11 on a Velis water heater: water overheating detected by one sensor
Risk level
High
Professional inspection is recommended.
Urgency
High
Quick answer
On an Ariston Velis, Er 11 means a single sensor has detected excessive water temperature on the outlet side. Take care when opening the hot tap, reset with ON/OFF and, if it returns, call the technical service.
Safety first
Stop and check this first
- The Velis leaves the factory set to 70 °C on the 30, 50 and 80 L models. Ariston warns that water above 50 °C at the tap can cause serious burns instantly and recommends a thermostatic mixing valve.
- Ariston reserves all maintenance for qualified personnel and requires the heater to be disconnected from the mains before any work. The cover, boards, probes, heating elements and anodes carry mains voltage or sit inside the tank: do not touch them yourself.
Safe checks you can perform
- Water temperature at the tap
- Reset with the ON/OFF button
- Sensor, board and scale check
Leave these tasks to a qualified professional
- Do not attempt this professional task: Diagnosing the overheating
- Do not attempt this professional task: Temperature check after the repair
What a technician must be able to justify
Technician visit
These are the steps they must carry out and show you. Tick them as they work: if steps are skipped, do not accept a part swap.
These are not instructions for opening or handling the equipment yourself. They are the checks that should support a technical conclusion.
Diagnosing the overheating
What they doThe technician measures the temperature sensors and checks that the board cuts the heating, following Ariston's list for boiling water.
They must show youthe measured sensor values against Ariston's specification.
In writingthe cause found, the part replaced and whether the element was descaled.
Temperature check after the repair
What they doAfter the repair, the technician lets the heater warm up and checks that it stops at the set temperature without repeating the code.
They must show youthe set point and the temperature on the display when it stops.
In writingthe final set point and the test result.
Before accepting a part or repair
Nothing has been shown yet. Do not accept a part swap based on the code alone.
Follow these steps
Note: Follow the documented order. An error code identifies the affected system, but it does not prove by itself which part has failed.
Water temperature at the tap
- Who:
- you.
- How:
- open the cold tap first, then the hot one slowly, without putting your hand under it; look for steam or boiling noises.
- Result that matters:
- Ariston warns that water above 50 °C can burn instantly and treats boiling water or steam as a fault.
- If steam or boiling water comes out:
- cut the heater's power with its external switch, as Ariston says, and leave it off until the visit.
- If the water is hot but without steam:
- go on to the reset and note the result.
- Evidence to keep:
- a note of what you saw at the tap and the time.
Evidence: Ariston Velis, instrucciones para la instalación, el uso y el mantenimiento de calentadores eléctricos
Reset with the ON/OFF button
- Who:
- you.
- How:
- switch the heater off with the ON/OFF button and switch it back on, as Ariston's error table says. Do not open the cover.
- Result that matters:
- whether, after the reset, the display stops showing Er and 11 and the status light stops flashing red.
- If the code clears:
- Ariston says the heater resumes normal operation; note the date in case it comes back.
- If Er 11 returns or the light stays red and flashing:
- Ariston says to contact the technical assistance centre; do not keep resetting it.
- Evidence to keep:
- a photo of the display with the code before and after the reset, with the date.
Evidence: Ariston Velis, instrucciones para la instalación, el uso y el mantenimiento de calentadores eléctricos
Sensor, board and scale check
- Who:
- a qualified Ariston service technician.
- How:
- with the heater disconnected from the mains, measures the sensor bars and checks the board; if the tank has to be drained, inspects the scale on the heating element.
- Result that matters:
- which of the three items Ariston lists for boiling water is out of specification.
- If a sensor reads out of specification:
- the sensor bar is confirmed.
- If the sensors read correctly:
- suspicion moves to the board or the scale.
- Evidence to keep:
- a job sheet with the measured values and photos of the element if it was removed.
Removing the heating element means draining the tank and disconnecting the mains. Technician only.
Evidence: Ariston Velis, instrucciones para la instalación, el uso y el mantenimiento de calentadores eléctricos
Still not solved
If the error persists, stop here. See what the technician must do and show you.
Where this code applies
A code is meaningful only inside the right product and version context.
Primary scope
- System
- Boilers
- Brand
- Ariston
- Product type
- Electric water heater
Known code variants
- 11
- Ariston Velis 11
- calentador Rinnai 11
- código 11 Rinnai
- E11
- E:11
- Er 11
- error 11 Rinnai
- Fujitsu 11
- Fujitsu E11
- Rinnai 11
- Rinnai 11 no ignition
- Rinnai code 11
- Rinnai code 11 tankless
- Rinnai error 11
- Toshiba 11
- Toshiba error 11
- Velis error 11
What it means
Ariston defines code 11 as excessive water temperature detected by a single sensor on the outlet side of the tank; 21 is the same on the inlet side. The control stops and flags the fault with the flashing red light. For water coming out boiling or with steam, Ariston says to cut the power and have the board, the scale build-up and the sensor bars checked. The code does not say which of them is the cause: the technician confirms it by measuring.
Warnings and stop conditions
- Highsource verified
The Velis leaves the factory set to 70 °C on the 30, 50 and 80 L models. Ariston warns that water above 50 °C at the tap can cause serious burns instantly and recommends a thermostatic mixing valve.
Evidence: Ariston Velis, instrucciones para la instalación, el uso y el mantenimiento de calentadores eléctricos
- Highsource verified
Ariston reserves all maintenance for qualified personnel and requires the heater to be disconnected from the mains before any work. The cover, boards, probes, heating elements and anodes carry mains voltage or sit inside the tank: do not touch them yourself.
Evidence: Ariston Velis, instrucciones para la instalación, el uso y el mantenimiento de calentadores eléctricos
Symptoms and causes
Probable causes · in order
- Overheating reading on a single sensorCommon
This is Ariston's definition of 11. The single sensor separates it from code 12, where the excess is general and Ariston attributes it to the board.
Evidence: Ariston Velis, instrucciones para la instalación, el uso y el mantenimiento de calentadores eléctricos
- Scale on the heating element and tankPossible
Ariston lists the scale level among the things to check when water comes out boiling and asks for the element to be descaled about every two years, more often with hard water.
Evidence: Ariston Velis, instrucciones para la instalación, el uso y el mantenimiento de calentadores eléctricos
- Sensor bar or circuit boardPossible
Ariston also lists the sensor bars and the board for boiling water. Only the technician's measurement tells a sensor reading wrongly from a board that does not cut out.
Evidence: Ariston Velis, instrucciones para la instalación, el uso y el mantenimiento de calentadores eléctricos
Virtual technician
Does 11 still appear after these checks?
Answer a few questions to narrow down the likely cause and the safest next action. Guidance only - it never replaces a professional.
Sources and technical references
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