- Boilers
- Gas boiler
F40
Ferroli F40 on a gas boiler: heating water pressure too high
Risk level
Medium
Proceed carefully and stop if the check is unclear.
Urgency
Medium
Quick answer
On the Ferroli DIVAtop MICRO LN F boiler, F40 means the heating water pressure is too high. It is a temporary lockout: read the pressure gauge with the system cold, make sure the filling tap is closed and book a check if the pressure stays high.
Safety first
Stop and check this first
- If you smell gas while the DIVAtop displays F40, do not touch switches, plugs or doorbells, avoid any flame, close the gas tap if it is within reach, open windows, leave the home and call your gas supplier emergency line or 112 from outside.
- Do not drain water from the system or operate the safety valve to bring the F40 pressure down: the Ferroli manual leaves repairs and any internal adjustment to an authorised technician.
Safe checks you can perform
- Read the gauge with the system cold
- Make sure the filling tap is closed
- Give the temporary lockout time to clear
- Look at the safety valve discharge
Leave these tasks to a qualified professional
- Do not attempt this professional task: Check the pressure and heating circuit
- Do not attempt this professional task: Test the expansion vessel and safety valve
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.
Check the pressure and heating circuit
What they doThe technician confirms the real pressure with the system cold, checks the filling tap and the circuit and sets the pressure back to its working value.
They must show youthe gauge reading before and after the adjustment.
In writingthe cold pressure they leave your DIVAtop at.
Test the expansion vessel and safety valve
What they doThey measure the expansion vessel pre-charge and verify that the safety valve operates and discharges properly into the funnel.
They must show youthe vessel pre-charge measurement.
In writingwhether the vessel or the valve was adjusted or replaced.
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 gauge with the system cold
Look at the pressure gauge at the bottom of the boiler, which shows the pressure even when the appliance is switched off. With the system cold it should sit around 1.0 bar; write down the exact figure you see while F40 is showing.
Evidence: Ferroli DIVAtop MICRO LN F instrucciones de uso instalación y mantenimiento
Make sure the filling tap is closed
Find the filling tap under the boiler, the one used to raise the pressure, and confirm by hand that it is shut, as the manual asks after every refill. Do not force it or use tools on it.
Evidence: Ferroli DIVAtop MICRO LN F instrucciones de uso instalación y mantenimiento
Give the temporary lockout time to clear
F faults reset by themselves once the pressure is back in range. Leave the boiler on for a few minutes, avoid pressing RESET repeatedly and watch whether F40 disappears and the gauge needle drops.
Evidence: Ferroli DIVAtop MICRO LN F instrucciones de uso instalación y mantenimiento
Look at the safety valve discharge
Without opening the casing, see whether the funnel or collection pipe connected to the safety valve is dripping or whether there is water on the floor below the boiler. If water is coming out, note it for the technician rather than draining the system yourself.
Evidence: Ferroli DIVAtop MICRO LN F instrucciones de uso instalación y mantenimiento
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
- Ferroli
- Product type
- Gas boiler
Known code variants
- anomalía F40 Miele
- anomalie F40 Miele
- code erreur F40 lave-vaisselle Miele
- DIVAtop F40
- DIVAtop MICRO F40
- DIVAtop MICRO LN F F40
- error F40 lavavajillas Miele
- errore F40 lavastoviglie Miele
- F40
- Fehlercode F40 Miele
- Ferroli F40
- guasto F40 Miele
- Miele dishwasher F40
- Miele F40
- Miele fault F40
- Miele Geschirrspüler Fehler F40
What it means
The fault table in the DIVAtop MICRO LN F manual describes F40 as incorrect system water pressure because the pressure is too high. Its solution column says to check the system, the safety valve and the expansion vessel. Faults starting with F are temporary lockouts that clear by themselves once the value returns to the normal operating range. The technical data give 3 bar as the maximum heating operating pressure, and the cold fill pressure should be about 1.0 bar. The code on its own does not prove that any particular part has failed.
Warnings and stop conditions
- Criticaleditorial warning
If you smell gas while the DIVAtop displays F40, do not touch switches, plugs or doorbells, avoid any flame, close the gas tap if it is within reach, open windows, leave the home and call your gas supplier emergency line or 112 from outside.
Evidence: Ferroli DIVAtop MICRO LN F instrucciones de uso instalación y mantenimiento
- Highsource verified
Do not drain water from the system or operate the safety valve to bring the F40 pressure down: the Ferroli manual leaves repairs and any internal adjustment to an authorised technician.
Evidence: Ferroli DIVAtop MICRO LN F instrucciones de uso instalación y mantenimiento
Symptoms and causes
Probable causes · in order
- System pressure above normalCommon
This is the only possible cause Ferroli lists for F40. Filling well above 1.0 bar when cold, or a filling tap left slightly open, fits it; the manual asks you to always close the tap when you finish.
Evidence: Ferroli DIVAtop MICRO LN F instrucciones de uso instalación y mantenimiento
- Expansion vessel needs checkingPossible
Checking the expansion vessel is one of the listed solutions for F40. The DIVAtop technical data give a 1 bar pre-charge, and measuring or correcting it is a job for the technician.
Evidence: Ferroli DIVAtop MICRO LN F instrucciones de uso instalación y mantenimiento
- Safety valve needs testingPossible
The table also says to check the heating safety valve, whose discharge must run to a funnel or collection pipe so that overpressure water does not end up on the floor.
Evidence: Ferroli DIVAtop MICRO LN F instrucciones de uso instalación y mantenimiento
Virtual technician
Does F40 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
Ferroli DIVAtop MICRO LN F instrucciones de uso instalación y mantenimiento
Ferroli · 2015 · manual
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