- Boilers
- Tankless gas water heater
EC
Junkers EC gas water heater: flame lost while running
Risk level
Medium
Proceed carefully and stop if the check is unclear.
Urgency
High
Quick answer
On Junkers Hydronext water heaters, EC means the flame stopped being detected while the heater was already running. Check that the gas valve is open, reset once and, if it happens again, call a gas technician.
Safety first
Stop and check this first
- If you smell gas after the flame goes out, do not try a reset. Avoid sparks: no switches, sockets, phone or doorbell inside, and no flames. Shut the gas at the main valve, ventilate by opening doors and windows, warn neighbours as you leave and call the fire service and gas company from outside.
- Repeated flame loss can go with poor combustion and carbon monoxide (CO). If a CO detector sounds or anyone feels dizzy or has a headache, shut off the gas, ventilate and leave the home before calling the technician.
Safe checks you can perform
- Check the gas valve is open
- Reset only once
- Note when it goes out
- Gas pressure and electrode inspection
Leave these tasks to a qualified professional
- Do not attempt this professional task: Gas pressure with the heater running
- Do not attempt this professional task: Ignition and ionisation electrodes
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.
Gas pressure with the heater running
What they doA qualified gas technician connects a gauge and measures supply pressure with the heater at full demand.
They must show youthe reading at rest and with the burner lit.
In writingboth pressures and the correction made to the gas installation.
Ignition and ionisation electrodes
What they doA qualified gas technician checks cleanliness, wear and gap of the electrodes and their wiring.
They must show youthe electrode inspected and its condition.
In writingwhether it was cleaned, adjusted or replaced 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.
Check the gas valve is open
- Who:
- you, without touching the inside.
- How:
- make sure the installation gas valve next to the heater is open, as the manual requires before use; if you use a cylinder, note whether it was just changed or is nearly empty.
- Result that matters:
- ruling out an obvious gas cut-off.
- If confirmed:
- if it was closed, open it and try once more.
- If not confirmed:
- move on to the next check.
- Evidence to keep:
- valve position and whether a cylinder was changed.
Evidence: Junkers Hydronext 2400S WD8/11..., manual de instalación y uso del calentador de gas (6720882438) · Junkers Hydronext 5600S WTD12/15/17..., manual de instalación y uso del calentador de gas (6721841217) · Junkers Hydronext 5700S WTD12/15/17..., manual de instalación y uso del calentador de gas (6720884104)
Reset only once
- Who:
- you, at the panel.
- How:
- on the 5700S and 5600S press the reset button for 5 seconds; on the 2400S close and reopen a hot tap, as its table says. Do not repeat it several times in a row.
- Result that matters:
- whether the heater runs through a full use without EC.
- If confirmed:
- note the time and watch whether it happens again.
- If not confirmed:
- leave the heater and call a technician.
- Evidence to keep:
- reset result and how long the next use lasted.
Evidence: Junkers Hydronext 2400S WD8/11..., manual de instalación y uso del calentador de gas (6720882438) · Junkers Hydronext 5600S WTD12/15/17..., manual de instalación y uso del calentador de gas (6721841217) · Junkers Hydronext 5700S WTD12/15/17..., manual de instalación y uso del calentador de gas (6720884104)
Note when it goes out
- Who:
- you, during normal use.
- How:
- watch whether EC appears soon after start-up, after several minutes or when another gas appliance is used at the same time, and check the FH menu on the 5700S or 5600S for repeats.
- Result that matters:
- a pattern that helps the technician measure pressure at the right moment.
- If confirmed:
- hand over your notes and the FH list.
- If not confirmed:
- say the shutdowns seem random.
- Evidence to keep:
- notes of each occurrence and a photo of the history.
Evidence: Junkers Hydronext 2400S WD8/11..., manual de instalación y uso del calentador de gas (6720882438) · Junkers Hydronext 5600S WTD12/15/17..., manual de instalación y uso del calentador de gas (6721841217) · Junkers Hydronext 5700S WTD12/15/17..., manual de instalación y uso del calentador de gas (6720884104)
Gas pressure and electrode inspection
- Who:
- a qualified gas technician investigating EC flame loss.
- How:
- measures the gas supply pressure with the heater running, checks the electrical supply and inspects the condition and position of the ignition and ionisation electrodes.
- Result that matters:
- which of the four points in the EC row is out of range.
- If confirmed:
- corrects the pressure, the connection or the electrode and tests a long run.
- If not confirmed:
- records the measurements before proposing another repair.
- Evidence to keep:
- report with the measured pressure and electrode condition.
Measuring gas pressure and handling the electrodes means opening the heater next to gas and mains connections, a job for a gas technician only.
Evidence: Junkers Hydronext 2400S WD8/11..., manual de instalación y uso del calentador de gas (6720882438) · Junkers Hydronext 5600S WTD12/15/17..., manual de instalación y uso del calentador de gas (6721841217) · Junkers Hydronext 5700S WTD12/15/17..., manual de instalación y uso del calentador de gas (6720884104)
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
- Junkers
- Product type
- Tankless gas water heater
Known code variants
- Bosch EC
- calentador Junkers EC
- deshumidificador Midea EC fuga refrigerante
- E C
- ec
- EC fuga de gas Samsung
- error EC aire Samsung
- Hydronext 2400S EC
- Hydronext 5600S EC
- Hydronext 5700S EC
- Junkers EC
- Midea dehumidifier EC refrigerant leak
- Midea EC
- Midea MAD50 EC
- Samsung AC EC error
- Samsung EC
- Samsung EC gas leak
What it means
The Hydronext 5700S, 5600S and 2400S fault tables define EC as no flame detected during operation, unlike EA, which relates to ignition. Bosch asks for checks on the gas supply pressure, mains connection, ignition electrode and ionisation electrode, all reserved for technicians, followed by a reset. The code alone does not prove that an electrode has failed.
Warnings and stop conditions
- Criticaleditorial warning
If you smell gas after the flame goes out, do not try a reset. Avoid sparks: no switches, sockets, phone or doorbell inside, and no flames. Shut the gas at the main valve, ventilate by opening doors and windows, warn neighbours as you leave and call the fire service and gas company from outside.
Evidence: Junkers Hydronext 2400S WD8/11..., manual de instalación y uso del calentador de gas (6720882438) · Junkers Hydronext 5600S WTD12/15/17..., manual de instalación y uso del calentador de gas (6721841217) · Junkers Hydronext 5700S WTD12/15/17..., manual de instalación y uso del calentador de gas (6720884104)
- Higheditorial warning
Repeated flame loss can go with poor combustion and carbon monoxide (CO). If a CO detector sounds or anyone feels dizzy or has a headache, shut off the gas, ventilate and leave the home before calling the technician.
Evidence: Junkers Hydronext 2400S WD8/11..., manual de instalación y uso del calentador de gas (6720882438) · Junkers Hydronext 5600S WTD12/15/17..., manual de instalación y uso del calentador de gas (6721841217) · Junkers Hydronext 5700S WTD12/15/17..., manual de instalación y uso del calentador de gas (6720884104)
Symptoms and causes
Probable causes · in order
- Low gas supply pressureCommon
The first check Bosch gives for EC is the pressure of the gas reaching the heater. If it drops during use, the burner can go out and the appliance no longer detects a flame.
Evidence: Junkers Hydronext 2400S WD8/11..., manual de instalación y uso del calentador de gas (6720882438) · Junkers Hydronext 5600S WTD12/15/17..., manual de instalación y uso del calentador de gas (6721841217) · Junkers Hydronext 5700S WTD12/15/17..., manual de instalación y uso del calentador de gas (6720884104)
- Faulty ionisation or ignition electrodesPossible
The EC row includes checking the ionisation and ignition electrodes. Dirt, wear or a poor position affects flame detection while the burner is running.
Evidence: Junkers Hydronext 2400S WD8/11..., manual de instalación y uso del calentador de gas (6720882438) · Junkers Hydronext 5600S WTD12/15/17..., manual de instalación y uso del calentador de gas (6721841217) · Junkers Hydronext 5700S WTD12/15/17..., manual de instalación y uso del calentador de gas (6720884104)
- Mains power connectionLess common
Bosch also asks for the mains connection to be checked. A poor electrical supply to the heater can interrupt flame monitoring during operation.
Evidence: Junkers Hydronext 2400S WD8/11..., manual de instalación y uso del calentador de gas (6720882438) · Junkers Hydronext 5600S WTD12/15/17..., manual de instalación y uso del calentador de gas (6721841217) · Junkers Hydronext 5700S WTD12/15/17..., manual de instalación y uso del calentador de gas (6720884104)
Virtual technician
Does EC 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
- 1
Junkers Hydronext 2400S WD8/11..., manual de instalación y uso del calentador de gas (6720882438)
Junkers (Bosch Termotecnia) · 2020 · manual
- 2
Junkers (Bosch Termotecnia) · 2022 · manual
- 3
Junkers (Bosch Termotecnia) · 2021 · manual
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