- Boilers
- Gas boiler
A04
Beretta A04 on a gas boiler: water pressure switch alarm
Risk level
Medium
Proceed carefully and stop if the check is unclear.
Urgency
Medium
Quick answer
Beretta A04 is the water pressure switch alarm. Read the pressure gauge: if it shows under 0.3 bar, turn the selector to off, open the filling tap to 1 to 1.5 bar and set it back to summer or winter. If pressure drops often, call the technician.
Safety first
Stop and check this first
- If you smell gas: Beretta says not to operate electrical switches, the phone or anything that could spark, to ventilate by opening doors and windows and to close the main gas tap. Then leave the home and call your gas distributor's emergency number from outside.
- Beretta asks you to check regularly that pressure does not drop below 1 bar. Do not top up with the boiler running: set the selector to off first and always close the filling tap afterwards.
Safe checks you can perform
- Gauge reading
- Top up with the filling tap
- Visible leaks
- Leak and pressure switch check by the technician
Leave these tasks to a qualified professional
- Do not attempt this professional task: Pressure drop test
- Do not attempt this professional task: Water pressure switch check
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.
Pressure drop test
What they doThe technician checks with the system at rest whether pressure falls and finds the leak.
They must show youthe pressure at the start and end of the test.
In writingwhere the leak was and what was repaired.
Water pressure switch check
What they doThe technician checks the water pressure switch responds to the actual system pressure.
They must show youthe gauge pressure against the switch's response.
In writingany part replaced and why.
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.
Gauge reading
- Who:
- you.
- How:
- look at the pressure shown on the boiler's gauge.
- Result that matters:
- whether it is below 0.3 bar.
- If it is below 0.3 bar:
- top up as the next check describes.
- If pressure is correct and A04 stays:
- do not top up; call the technical service.
- Evidence to keep:
- a photo of the gauge and the display.
Evidence: Beretta Ciao Green 25 y 29 C.S.I., manual de instalación y uso
Top up with the filling tap
- Who:
- you.
- How:
- turn the function selector to off (OFF), open the filling tap until pressure is between 1 and 1.5 bar, close it and set the selector back to summer or winter, as Beretta describes.
- Result that matters:
- whether the boiler runs its purge cycle of about 2 minutes and works again.
- If it works and pressure holds:
- it was low pressure; note the date.
- If pressure soon drops again:
- there is a leak; call the technical service.
- Evidence to keep:
- photos of the gauge before and after and the date of each top up.
Evidence: Beretta Ciao Green 25 y 29 C.S.I., manual de instalación y uso
Visible leaks
- Who:
- you.
- How:
- look under the boiler, radiators and valves for water or drips, without taking anything apart.
- Result that matters:
- whether there is a visible leak.
- If you see water:
- Beretta says to shut off the water supply and tell the technical service.
- If everything is dry and pressure holds:
- nothing more is needed.
- Evidence to keep:
- photos of stains or drips.
Evidence: Beretta Ciao Green 25 y 29 C.S.I., manual de instalación y uso
Leak and pressure switch check by the technician
- Who:
- technician from the technical service.
- How:
- looks for the water leak and checks the water pressure switch.
- Result that matters:
- whether there is a leak or the switch has failed.
- If the leak is found:
- it is repaired.
- If there is no leak and A04 stays with correct pressure:
- the switch is checked.
- Evidence to keep:
- a report of what was checked and repaired.
Beretta reserves servicing and maintenance for qualified staff of its technical service: opening the boiler is not the user's job.
Evidence: Beretta Ciao Green 25 y 29 C.S.I., manual de instalación y uso
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
- Beretta
- Product type
- Gas boiler
Known code variants
- A 04
- aerotermia Toshiba A04
- Beretta A 04
- bomba de calor Toshiba A04 heladas
- Ciao Green A04
- Error A04 Beretta
- error A04 Estia antihielo
- Estia error A04 antifreeze
- Estia R32 A04 congelación
- Estia R32 A04 freezing
- Toshiba air to water A04 frost
- Toshiba Estia A04
- Toshiba heat pump A04
- Toshiba HWT A04
What it means
In the Ciao Green C.S.I. table, A04 is the water pressure switch alarm, a permanent lockout; the display also shows a symbol next to the code. Beretta says to check the gauge and, if it reads under 0.3 bar, top up with the filling tap to between 1 and 1.5 bar; the boiler then runs a purge cycle of about 2 minutes. The switch watches heating circuit pressure; the code does not say where the water is lost.
Warnings and stop conditions
- Criticaleditorial warning
If you smell gas: Beretta says not to operate electrical switches, the phone or anything that could spark, to ventilate by opening doors and windows and to close the main gas tap. Then leave the home and call your gas distributor's emergency number from outside.
Evidence: Beretta Ciao Green 25 y 29 C.S.I., manual de instalación y uso
- Mediumsource verified
Beretta asks you to check regularly that pressure does not drop below 1 bar. Do not top up with the boiler running: set the selector to off first and always close the filling tap afterwards.
Evidence: Beretta Ciao Green 25 y 29 C.S.I., manual de instalación y uso
Symptoms and causes
Probable causes · in order
- Low system pressureCommon
This is what the switch watches. If the gauge shows under 0.3 bar and pressure holds after topping up, this was the cause.
Evidence: Beretta Ciao Green 25 y 29 C.S.I., manual de instalación y uso
- Repeated water lossPossible
If pressure drops often, Beretta says to call the technical service; water is escaping somewhere in the system or the boiler.
Evidence: Beretta Ciao Green 25 y 29 C.S.I., manual de instalación y uso
- Pressure switch not respondingPossible
If the gauge shows correct pressure and A04 stays, the technician must check the water pressure switch.
Evidence: Beretta Ciao Green 25 y 29 C.S.I., manual de instalación y uso
Virtual technician
Does A04 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
Beretta Ciao Green 25 y 29 C.S.I., manual de instalación y uso
Beretta · 2015 · manual
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