- Boilers
- Gas boiler
F22
Vaillant boiler F22: too little heating water or system pressure
Evidence linked to this decision
View source: HSE gas safety for homeownersRisk level
High
Professional inspection is recommended.
Urgency
High
Quick answer
F22 means too little heating water or system pressure in the cited model family. Do not buy a part from the display. First read the external gauge once with the boiler cold and compare it only with the exact user manual. A low reading supports the water-pressure branch; a normal reading with F22 returning moves diagnosis to leakage or sensing.
Safety first
Stop and check this first
- Gas smell, a CO alarm, smoke, symptoms, escaping hot water or abnormal combustion means no reset: leave if safe and call the local gas emergency service from outside. Never open the boiler casing.
Safe checks you can perform
- Capture the failure pattern before clearing it
- Run the safe discriminating check
- Use recurrence as the decision point
Leave these tasks to a qualified professional
- Do not attempt this professional task: Measured service test for F22
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.
Measured service test for F22
What they doLeak-test the sealed circuit and measure the pressure sensor against a calibrated reference.
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.
Capture the failure pattern before clearing it
Photograph F22, both exact model identifiers and the operating state. Read the external gauge once with the boiler cold and compare it only with the exact user manual.
Gas smell, a CO alarm, smoke, symptoms, escaping hot water or abnormal combustion means no reset: leave if safe and call the local gas emergency service from outside. Never open the boiler casing.
Evidence: Vaillant UK boiler fault codes list
Run the safe discriminating check
Stay outside sealed or powered compartments. A low reading supports the water-pressure branch; a normal reading with F22 returning moves diagnosis to leakage or sensing. If the observation is unclear, stop and treat the internal branch as unresolved.
Gas smell, a CO alarm, smoke, symptoms, escaping hot water or abnormal combustion means no reset: leave if safe and call the local gas emergency service from outside. Never open the boiler casing.
Evidence: Vaillant UK boiler fault codes list
Use recurrence as the decision point
Only if the exact user manual permits it and no stop condition exists, make one controlled attempt. If F22 returns, stop; repeated resets destroy evidence and can worsen the fault.
Gas smell, a CO alarm, smoke, symptoms, escaping hot water or abnormal combustion means no reset: leave if safe and call the local gas emergency service from outside. Never open the boiler casing.
Evidence: Vaillant UK boiler fault codes list
Still not solved
If the error persists, stop here. See what the technician must do and show you.
Virtual technician
Does F22 still appear after these checks?
This guided flow uses the exact code and your answers to choose a test, an expected result and the next branch.
Where this code applies
A code is meaningful only inside the right product and version context.
Primary scope
- System
- Boilers
- Brand
- Vaillant
- Product type
- Gas boiler
Known code variants
- 22
- code erreur F22 chaudière Vaillant
- codice F22 Vaillant
- código F22 Vaillant
- error F22 caldera Vaillant
- Error F22 Saunier Duval
- errore F22 caldaia Vaillant
- F 22
- Fehlercode F22 Vaillant
- Glow worm boiler F22
- Glow worm F22
- Glow-worm F.22
- Glow-worm F22
- Glow-worm F9 older boilers
- panne F22 Vaillant
- Saunier Duval F.22
- ThemaFast Condens F.22
- Vaillant boiler F22
- Vaillant F.22
- Vaillant F22
- Vaillant Fehler F22
What it means
Vaillant's official regional documentation associates F22 with too little heating water or system pressure. That is the controller's observed condition, not a universal failed component. Confirm the exact model before using this decision path; the same code can mean something else on another product family.
Warnings and stop conditions
- Highsource verified
Gas smell, a CO alarm, smoke, symptoms, escaping hot water or abnormal combustion means no reset: leave if safe and call the local gas emergency service from outside. Never open the boiler casing.
Evidence: Vaillant UK boiler fault codes list
Symptoms and causes
Probable causes · in order
- First branch to separate: visible system pressure below the model's permitted bandPossible
The documented condition is too little heating water or system pressure. Discriminating observation: Read the external gauge once with the boiler cold and compare it only with the exact user manual. Expected reading and decision: A low reading supports the water-pressure branch; a normal reading with F22 returning moves diagnosis to leakage or sensing.
Evidence: Vaillant UK boiler fault codes list
- If that branch is ruled out: leak, pressure sensor or sealed-system faultPossible
leak, pressure sensor or sealed-system fault remains possible only after the safe observation is recorded. The next evidence is measured, not another reset: Leak-test the sealed circuit and measure the pressure sensor against a calibrated reference.
Evidence: Vaillant UK boiler fault codes list
Sources and technical references
- 1
Health and Safety Executive · official_doc
- 2
Vaillant UK boiler fault codes list
Vaillant UK · official_doc
- 3
Vaillant ecoTEC plus current installation and maintenance instructions
Vaillant UK · manual
Was this entry useful?