- Boilers
- Gas boiler
EA
Junkers EA on a gas boiler: no flame detected
Risk level
High
Professional inspection is recommended.
Urgency
High
Quick answer
Junkers EA means the boiler detects no flame after trying to light. Check the gas valve is open and there is gas in the home, see whether the condensate pipe is frozen and reset with the reset key.
Safety first
Stop and check this first
- If you smell gas: close the gas shut-off valve, open the windows, do not operate switches, put out any flame and, from outside the home, call the gas company and an authorised installer. If you smell flue gases: switch the boiler off, open doors and windows and call the installer.
- Bosch warns of the fall risk: never try to thaw a condensate pipe that is high up, and do not use boiling water, which can damage the pipe.
Safe checks you can perform
- Gas valve and supply
- Condensate pipe and flue, from outside
- Reset with the reset key
Leave these tasks to a qualified professional
- Do not attempt this professional task: Ionisation and electrode test
- Do not attempt this professional task: CO2 or O2 measurement and adjustment
- Do not attempt this professional task: Gas inlet pressure measurement
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.
Ionisation and electrode test
What they doThe technician checks the ignition and ionisation electrodes and their cables and tests the flame signal.
They must show youthe electrodes inspected and the flame signal reading.
In writingwhat was cleaned or replaced and why.
CO2 or O2 measurement and adjustment
What they doAfter any work on the burner, the technician measures CO2 or O2 with an analyser and sets the gas/air ratio as Bosch requires.
They must show youthe analyser printout.
In writingthe CO2 or O2 values recorded in the commissioning log.
Gas inlet pressure measurement
What they doThe technician measures gas pressure at the boiler's test point with a manometer. On the CerapurComfort, Bosch allows 17 to 25 mbar on natural gas and 25 to 45 mbar on LPG.
They must show youthe measured value against that range.
In writingthe measured pressure and whether it was a supply problem.
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.
Gas valve and supply
- Who:
- you.
- How:
- check the boiler's gas shut-off valve is open, as Bosch asks for EA, and see whether the gas hob lights. Do not touch anything inside the boiler.
- Result that matters:
- whether gas reaches the boiler.
- If the valve was closed or there is no gas in the home:
- Bosch says to contact the gas supplier.
- If there is gas:
- the cause is in the boiler or its flue; carry on.
- Evidence to keep:
- a photo of the valve and a note of whether the hob worked.
Evidence: Junkers CerapurComfort ZWBC 25-2 C, instrucciones de instalación y manejo para el técnico · Junkers Cerapur Excellence Compact, instrucciones de uso de la caldera mural a gas de condensación
Condensate pipe and flue, from outside
- Who:
- you.
- How:
- look at the condensate pipe where it leaves the building and at the flue outlet, without climbing. If the pipe is frozen at ground level, Bosch allows thawing it with warm, not boiling, water or a hot water bottle.
- Result that matters:
- whether the pipe is frozen or blocked or the flue outlet is damaged or covered.
- If the pipe was frozen and you thaw it:
- Bosch says to hold reset for five seconds and wait two to three minutes.
- If the flue outlet is damaged or covered:
- do not touch it and call the technician.
- Evidence to keep:
- photos of the pipe and the terminal and the time.
Evidence: Junkers Cerapur Excellence Compact, instrucciones de uso de la caldera mural a gas de condensación
Reset with the reset key
- Who:
- you.
- How:
- if the reset key is flashing, hold it until the display changes, as Bosch says; if it is not flashing, switch the boiler off and on.
- Result that matters:
- whether the boiler runs again and shows the flow temperature.
- If it starts:
- note the date; if EA returns, call the service centre.
- If EA returns straight away:
- Bosch explains some faults cannot be cleared by a reset; call the service centre with the code and the three digit number shown below it, for example 227.
- Evidence to keep:
- a photo of the display with EA and the three digit number.
Evidence: Junkers CerapurComfort ZWBC 25-2 C, instrucciones de instalación y manejo para el técnico · Junkers Cerapur Excellence Compact, instrucciones de uso de la caldera mural a gas de condensación
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
- Gas boiler
Known code variants
- Bosch EA caldera
- caldera Worcester EA
- Cerapur EA
- E A
- E-A
- EA 227
- Error EA Junkers
- error EA Worcester Bosch
- Junkers EA
- Worcester boiler EA fault
- Worcester Bosch EA
- Worcester EA
What it means
In the CerapurComfort fault table, EA is "no flame detected" and the ZWE manual calls it no ionisation current: the control does not see a flame and shuts the gas. Bosch checks the gas valve, gas pressure, power supply, ignition and ionisation electrodes with their cables, the flue and the gas/air ratio. For the Cerapur Excellence Compact it also lists a blocked condensate outlet. The code does not say which one failed.
Warnings and stop conditions
- Criticalsource verified
If you smell gas: close the gas shut-off valve, open the windows, do not operate switches, put out any flame and, from outside the home, call the gas company and an authorised installer. If you smell flue gases: switch the boiler off, open doors and windows and call the installer.
Evidence: Junkers CerapurComfort ZWBC 25-2 C, instrucciones de instalación y manejo para el técnico · Junkers ZWE 24-3 y 28-3 H A con Bosch Heatronic, instrucciones de instalación
- Highsource verified
Bosch warns of the fall risk: never try to thaw a condensate pipe that is high up, and do not use boiling water, which can damage the pipe.
Evidence: Junkers Cerapur Excellence Compact, instrucciones de uso de la caldera mural a gas de condensación
Symptoms and causes
Probable causes · in order
- No gas or low gas pressureCommon
Bosch lists it first: valve closed or low supply pressure. If the hob does not light either, it is this and your distributor fixes it.
Evidence: Junkers CerapurComfort ZWBC 25-2 C, instrucciones de instalación y manejo para el técnico · Junkers Cerapur Excellence Compact, instrucciones de uso de la caldera mural a gas de condensación
- Blocked or frozen condensatePossible
On the Cerapur Excellence Compact, a frozen or blocked condensate pipe shuts the boiler down; it happens in frost when the pipe runs outside.
Evidence: Junkers Cerapur Excellence Compact, instrucciones de uso de la caldera mural a gas de condensación
- Damaged or blocked fluePossible
Bosch says to check the flue outlet for damage or blockage; a blocked terminal prevents a stable flame.
Evidence: Junkers CerapurComfort ZWBC 25-2 C, instrucciones de instalación y manejo para el técnico · Junkers Cerapur Excellence Compact, instrucciones de uso de la caldera mural a gas de condensación
- Ignition or ionisation electrodesPossible
With gas and flue fine, the electrodes and their cables are next on Bosch's list; measuring ionisation confirms it.
Evidence: Junkers CerapurComfort ZWBC 25-2 C, instrucciones de instalación y manejo para el técnico · Junkers ZWE 24-3 y 28-3 H A con Bosch Heatronic, instrucciones de instalación
Virtual technician
Does EA 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 CerapurComfort ZWBC 25-2 C, instrucciones de instalación y manejo para el técnico
Junkers (Bosch Termotecnia) · 2012 · manual
- 2
Junkers Cerapur Excellence Compact, instrucciones de uso de la caldera mural a gas de condensación
Junkers (Bosch Termotecnia) · 2019 · manual
- 3
Junkers ZWE 24-3 y 28-3 H A con Bosch Heatronic, instrucciones de instalación
Junkers (Bosch Termotecnia) · 2000 · manual
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