- Boilers
- Gas boiler
E03
Domusa E03 on an Avanttia NG gas boiler: high water pressure
Risk level
Medium
Proceed carefully and stop if the check is unclear.
Urgency
Medium
Quick answer
Domusa E03 warns of high water pressure: the Avanttia NG heating circuit is above 2.7 bar. Read the digital pressure gauge, note the figure and call Domusa's SAT to bring it down to 1 to 1.5 bar; the drain valve sits inside the boiler.
Safety first
Stop and check this first
- Domusa places the drain valve inside the boiler and keeps the interior for authorised staff: do not remove the casing to let water out yourself.
- If you notice a smell of gas while E03 is showing, leave the boiler and switches alone; the Domusa guide says to open doors and windows, close the main gas valve, avoid smoking or sparks, keep people away and notify the gas supplier. Phone from outside the home.
Safe checks you can perform
- Read the digital pressure gauge
- Check the In 9 value and the error history
- Do not open the casing to drain
- Pressure adjustment by the SAT
Leave these tasks to a qualified professional
- Do not attempt this professional task: Bring pressure back to the cold range
- Do not attempt this professional task: Expansion vessel check
- Do not attempt this professional task: Pressure sensor cross-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.
Bring pressure back to the cold range
What they doThe technician drains water through the primary drain valve until the circuit sits at 1 to 1.5 bar cold, with the boiler off and without power.
They must show youthe digital gauge pressure before and after draining.
In writingthe final cold pressure and the date.
Expansion vessel check
What they doConfirms the heating expansion vessel is full according to the figures on its plate, as Domusa's yearly service requires.
They must show youthe measured value against the vessel plate.
In writingthe vessel condition and whether it was adjusted or replaced.
Pressure sensor cross-check
What they doIf real pressure is in range and E03 persists, compares the sensor reading (In 9) with a reference measurement before replacing anything.
They must show youboth readings side by side.
In writingthe part replaced, if any, 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.
Read the digital pressure gauge
- Who:
- you.
- How:
- look at the pressure figure on the digital pressure gauge of the display and write it down with the time and whether the boiler was heating or idle.
- Result that matters:
- knowing whether pressure is above 2.7 bar, the limit that triggers E03.
- If it is above 2.7 bar:
- do not try to drain it yourself, call Domusa's SAT.
- If it reads 1 to 1.5 bar and the alarm stays:
- tell the SAT, as that points at the reading.
- Evidence to keep:
- photo of the display with E03 and the pressure visible.
Evidence: Domusa Teknik Avanttia NG operation user guide (CDOC001980)
Check the In 9 value and the error history
- Who:
- you.
- How:
- open the Info menu by pressing the heating + button and RESET together until the circle completes, then use the DHW buttons to step through AL (last 10 errors) and In 9 (water pressure sensor).
- Result that matters:
- having the sensor value and how often E03 has appeared.
- If E03 shows several times under AL:
- report it to the technician as a repeat fault.
- If it appears only once:
- note it anyway for the visit.
- Evidence to keep:
- photo of In 9 and the AL codes.
Evidence: Domusa Teknik Avanttia NG operation user guide (CDOC001980)
Do not open the casing to drain
- Who:
- you.
- How:
- note that the guide places the primary drain valve inside the boiler next to the heat exchanger and that Domusa forbids access to sealed components; leave that step to the SAT.
- Result that matters:
- not handling the inside of a gas appliance.
- If someone has already opened the boiler:
- tell the technician on arrival.
- If the boiler is still closed:
- wait for the SAT without touching anything inside.
- Evidence to keep:
- note of who handled the boiler and when.
Evidence: Domusa Teknik Avanttia NG operation user guide (CDOC001980)
Pressure adjustment by the SAT
- Who:
- technician from Domusa's official SAT or authorised staff.
- How:
- lowers the pressure through the drain valve to 1 to 1.5 bar with the boiler off and unplugged, checks the expansion vessel against its plate and verifies the sensor reading.
- Result that matters:
- cold pressure within range and no E03.
- If pressure climbs again by itself:
- the cause must be traced in the installation.
- If it stays stable:
- the final value goes in the report.
- Evidence to keep:
- report with pressure before and after.
Domusa reserves maintenance for authorised staff and asks for the boiler to be switched off and unplugged while draining; inside are mains voltage parts and the gas valve.
Evidence: Domusa Teknik Avanttia NG operation user guide (CDOC001980)
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
- Domusa Teknik
- Product type
- Gas boiler
Known code variants
- Avanttia NG E03
- caldera Domusa E03 exceso de presión
- Candy dryer E03
- Candy dryer E3
- Candy dryer water container full E3
- Candy secadora E03
- Candy secadora E3
- Candy tumble dryer 3 flashes
- Domusa alta presión de agua
- Domusa boiler E03 excess pressure
- Domusa E 03
- Domusa error E03
- Domusa high water pressure
- E 03
- E 3
- E-03
- E-3
- E03
- E3
- Error 3
- Error E03 Domusa
- Saeco brew group dirty
- Saeco brew group needs grease
- Saeco E3
- Saeco engrasar grupo de café
- Saeco error 03
- Saeco GranAroma error 03
- Saeco grupo de preparación sucio
- Saeco SM6580 error 03
- Saeco SM6580 error code 03
- secadora Candy 3 parpadeos
- secadora Candy deposito lleno E3
What it means
In the Avanttia NG user guide (CDOC001980), Domusa explains that a sensor measures heating circuit pressure and shows it on the digital pressure gauge. Above 0.27 MPa (2.7 bar) the display shows E03 to warn of excess pressure. Domusa advises contacting the Technical Assistance Service and draining until the pressure sits between 1 and 1.5 bar. Other Domusa models may use different codes. This alarm on its own does not prove that the sensor or any other part has failed.
Warnings and stop conditions
- Mediumsource verified
Domusa places the drain valve inside the boiler and keeps the interior for authorised staff: do not remove the casing to let water out yourself.
Evidence: Domusa Teknik Avanttia NG operation user guide (CDOC001980)
- Criticalsource verified
If you notice a smell of gas while E03 is showing, leave the boiler and switches alone; the Domusa guide says to open doors and windows, close the main gas valve, avoid smoking or sparks, keep people away and notify the gas supplier. Phone from outside the home.
Evidence: Domusa Teknik Avanttia NG operation user guide (CDOC001980)
Symptoms and causes
Probable causes · in order
- Circuit filled above the stated rangeCommon
Domusa states that cold installation pressure must sit between 1 and 1.5 bar; overfilling can push the sensor reading past the 2.7 bar limit.
Evidence: Domusa Teknik Avanttia NG operation user guide (CDOC001980)
- Heating expansion vessel due for a checkPossible
Among the yearly service points, Domusa asks for the expansion vessel to be full according to its rating plate; checking it is a job for authorised staff.
Evidence: Domusa Teknik Avanttia NG operation user guide (CDOC001980)
- Pressure sensor readingLess common
The display figure and the In 9 value come from the water pressure sensor; the code cannot tell a real high pressure from a wrong reading, which the SAT verifies.
Evidence: Domusa Teknik Avanttia NG operation user guide (CDOC001980)
Virtual technician
Does E03 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
Domusa Teknik Avanttia NG, guía rápida de funcionamiento para el usuario (CDOC001923)
Domusa Teknik · 2020 · manual
- 2
Domusa Teknik Avanttia NG operation user guide (CDOC001980)
Domusa Teknik · 2020 · manual
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