Vaillant F28: repeated ignition failure on an ecoTEC
F28 appears after the boiler has tried and failed to light several times in a row. It is the same family of fault as a Worcester EA but the diagnostic path on an ecoTEC is slightly different.
Understanding an F28 ignition failure before you spend money
An engineer works from the gas side inwards: standing and working pressure at the appliance, then the gas valve offset, then ignition components, then the condensate route. Vaillant gas valves are calibrated by combustion analysis rather than adjusted by feel, so a flue gas analyser reading is part of any honest F28 diagnosis.
Detail that affects your quote for an F28 ignition failure
- Working gas pressure must be measured, not assumed
- A blocked condensate trap gives F28 in freezing weather
- Electrode gap and condition is checked against Vaillant's figures
- Combustion analysis confirms the fix rather than guessing
- LPG conversions need the correct kit and settings
Where we deal with this
Relevant registrations
- Gas Safe registered for domestic gas boiler work
- OFTEC registered for oil boiler work
- Worcester Bosch Accredited Installer
Talk to us about an F28 ignition failure
The honest position: F28 is a diagnosis job, not a parts lottery — gas pressure, combustion figures and condensate before anything is replaced.
Use the enquiry form to describe the appliance, fault code and what changed before the problem started.
Related help pages
- Noise diagnosisHumming or vibrating pump: noise diagnosis on a heating system
- Fan speed mismatchBaxi E168: fan speed fault on newer Baxi appliances
- Internal leak tracingWater dripping from inside the boiler casing: where it usually starts
- Repressurising guideHow to repressurise a boiler safely using the filling loop
- Pub servicingHeating and hot water servicing in pubs
- System design comparisonLow-loss header vs manifold in multi-zone systems
Services that cover this
Questions we get asked
- Could my meter be the problem?
- Yes. Undersized or partly blocked supply pipework and low standing pressure both cause repeated ignition failures.
- Is it worth repairing an older ecoTEC?
- Usually, if parts are still available and the heat exchanger is sound. We give you the repair-versus-replace numbers before you decide.
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