- Boilers
- Gas boiler
F62
Saunier Duval F.62 on a gas boiler: delayed gas valve shut off
Risk level
High
Professional inspection is recommended.
Urgency
High
Quick answer
Saunier Duval F.62 means the gas valve switches off with a delay; one possible cause is that it is not tight. If you smell gas, leave home and call from outside. If not, press reset once and, if it returns, call the official service centre.
Safety first
Stop and check this first
- If you smell gas: Saunier Duval says to keep away from the area, open doors and windows, light no flames and do not smoke, do not touch switches, sockets, doorbells or phones, close the meter and appliance gas valves, warn neighbours without the bell, leave the building and call the gas company from a phone outside.
- If you smell fumes indoors: Saunier Duval says to open doors and windows fully, switch the appliance off and call a professional. Poor combustion or fumes that do not clear properly can fill the home with carbon monoxide, which has no smell: if you feel headache, dizziness or nausea, ventilate, get out and call for help. A CO alarm helps.
- Do not touch the gas valve or its screws. Saunier Duval forbids tampering with the Offset adjustment screw, sealed at the factory, and reserves gas adjustments for a qualified installer.
Safe checks you can perform
- Gas smell near the boiler
- Code on the display and other codes
- One reset with the fault key
- Tightness, gas valve and flame signal checked by the technician
Leave these tasks to a qualified professional
- Do not attempt this professional task: Tightness test of gas valve and gas pipe
- Do not attempt this professional task: Electrode and flame signal
- Do not attempt this professional task: Combustion analysis after the repair
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.
Tightness test of gas valve and gas pipe
What they doThe technician checks the tightness of the gas pipe and the gas valve and that no gas escapes from the appliance.
They must show youthe tightness test carried out.
In writingthe result and, if the gas valve is replaced, its reference and why.
Electrode and flame signal
What they doChecks the ignition and flame monitoring electrode, its cable and when the board stops seeing a flame after the gas is cut.
They must show youthe electrode condition and the measured signal against the manufacturer's specification.
In writingwhat was checked and replaced.
Combustion analysis after the repair
What they doConnects an analyser to the flue gas test point, runs the boiler at full load with test programme P.01 at 100, waits for a stable reading and measures CO2.
They must show youthe measured CO2 against the manufacturer's table for your gas type.
In writingthe value and the test run.
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 smell near the boiler
- Who:
- you.
- How:
- without touching the boiler or any switch, notice when you walk into the room whether you smell gas.
- Result that matters:
- whether there is a gas smell.
- If you smell gas:
- do not reset; follow the Saunier Duval instructions: leave, do not touch switches, close the meter valve and call from outside.
- If you smell nothing:
- go on to the next check.
- Evidence to keep:
- the time and place you noticed the smell, if any.
Evidence: Saunier Duval ThemaFast Condens, instrucciones de funcionamiento 0020238204_00
Code on the display and other codes
- Who:
- you.
- How:
- take a photo of the display. If several faults are present, Saunier Duval shows them alternately every two seconds: wait a few seconds and note them all.
- Result that matters:
- whether F.62 appears alone or alternates with other codes.
- If it appears alone:
- the fault is in the gas valve closing or the flame signal; go on to the next check.
- If it alternates with others:
- note them all; the technician needs them for the diagnosis.
- Evidence to keep:
- photos of the display with date and time.
Evidence: Saunier Duval ThemaFast Condens, instrucciones de funcionamiento 0020238204_00
One reset with the fault key
- Who:
- you.
- How:
- press the fault clearing (reset) key and wait five seconds, as Saunier Duval describes. Do it once only.
- Result that matters:
- whether F.62 comes back.
- If it clears and stays away:
- note the date and tell the technician at the next service.
- If it persists or returns:
- do not keep resetting; call the official service centre.
- Evidence to keep:
- a photo of the display with the code and the time.
Evidence: Saunier Duval ThemaFast Condens, instrucciones de funcionamiento 0020238204_00
Tightness, gas valve and flame signal checked by the technician
- Who:
- official service centre technician or qualified installer.
- How:
- checks the tightness of the gas valve and gas pipe, how the gas valve closes and the flame signal the board receives, and finally the electronics.
- Result that matters:
- whether the gas valve lets gas through or is slow to close.
- If the gas valve is not tight or closes late:
- it is replaced and combustion is checked.
- If the gas valve is fine:
- the electrode, flame signal and electronics are checked.
- Evidence to keep:
- a report with the tightness test and what was replaced.
The gas valve, the flame and the flue are gas and combustion parts. Saunier Duval reserves this work for a qualified installer: do not open the casing.
Evidence: Saunier Duval ThemaFast Condens, instrucciones de instalación y mantenimiento 0020238203_00
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
- Saunier Duval
- Product type
- Gas boiler
Known code variants
- 62
- BlueHelix Pro F62
- code erreur F62 chaudière Vaillant
- codice F62 Vaillant
- código F62 Vaillant
- error F62 caldera Vaillant
- Error F62 Ferroli
- Error F62 Saunier Duval
- errore F62 caldaia Vaillant
- F 62
- Fehlercode F62 Vaillant
- Ferroli A54
- Ferroli A55
- Ferroli F62
- Ferroli F63
- panne F62 Vaillant
- Saunier Duval F.62
- ThemaFast Condens F.62
- Vaillant boiler F62
- Vaillant F.62
- Vaillant F62
- Vaillant Fehler F62
What it means
In the ThemaFast Condens table, F.62 is gas valve fault, switch off delay. Saunier Duval gives four causes: delayed switch off of the gas valve, delayed loss of the flame signal, a gas valve that is not tight and an electronics fault. A gas valve that is not tight lets gas through when it should be closed, so this code calls for more caution than a sensor fault. The code does not say which of the four causes is acting.
Warnings and stop conditions
- Criticalsource verified
If you smell gas: Saunier Duval says to keep away from the area, open doors and windows, light no flames and do not smoke, do not touch switches, sockets, doorbells or phones, close the meter and appliance gas valves, warn neighbours without the bell, leave the building and call the gas company from a phone outside.
Evidence: Saunier Duval ThemaFast Condens, instrucciones de funcionamiento 0020238204_00
- Higheditorial warning
If you smell fumes indoors: Saunier Duval says to open doors and windows fully, switch the appliance off and call a professional. Poor combustion or fumes that do not clear properly can fill the home with carbon monoxide, which has no smell: if you feel headache, dizziness or nausea, ventilate, get out and call for help. A CO alarm helps.
Evidence: Saunier Duval ThemaFast Condens, instrucciones de funcionamiento 0020238204_00
- Highsource verified
Do not touch the gas valve or its screws. Saunier Duval forbids tampering with the Offset adjustment screw, sealed at the factory, and reserves gas adjustments for a qualified installer.
Evidence: Saunier Duval ThemaFast Condens, instrucciones de instalación y mantenimiento 0020238203_00 · Saunier Duval ThemaFast Condens, instrucciones de funcionamiento 0020238204_00
Symptoms and causes
Probable causes · in order
- Gas valve switching off latePossible
The valve is slow to close when the board cuts the gas. Saunier Duval lists it first for F.62; the technician checks it.
Evidence: Saunier Duval ThemaFast Condens, instrucciones de instalación y mantenimiento 0020238203_00
- Flame signal going off latePossible
The board keeps seeing a flame signal for a while after the gas is cut. The technician checks the ignition and flame monitoring electrode and that signal.
Evidence: Saunier Duval ThemaFast Condens, instrucciones de instalación y mantenimiento 0020238203_00
- Gas valve not tightPossible
It is the most serious cause: the valve does not close fully. It is confirmed with a tightness test; if you smell gas near the boiler, treat it as a leak.
Evidence: Saunier Duval ThemaFast Condens, instrucciones de instalación y mantenimiento 0020238203_00
- Electronics faultLess common
If gas valve and flame signal are fine, the circuit board remains. It is the last cause Saunier Duval lists.
Evidence: Saunier Duval ThemaFast Condens, instrucciones de instalación y mantenimiento 0020238203_00
Virtual technician
Does F62 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
Saunier Duval ThemaFast Condens, instrucciones de instalación y mantenimiento 0020238203_00
Saunier Duval · 2016 · manual
- 2
Saunier Duval ThemaFast Condens, instrucciones de funcionamiento 0020238204_00
Saunier Duval · 2016 · manual
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