Work Guaranteed
Same Day Service
Established in 2009
Certified Engineers
F.29 on a Vaillant boiler means the flame went out while the boiler was running and it could not relight. Check that your gas supply is working and has credit, thaw the condensate pipe if it is frozen, and reset the boiler once. If F.29 comes back, the cause is inside the boiler and needs a Gas Safe engineer.
For other codes, see our Vaillant fault codes hub.
These are the checks Vaillant gives on its fault code page:
Safe for you to try
Gas turned off at the meter, no credit on a prepayment meter, or a supply problem in the street. If other gas appliances do not work, contact your gas supplier.
The most common winter cause. Water backs up into the boiler and puts the flame out. You can thaw a frozen pipe yourself.
Gas Safe engineer only A worn, dirty or badly positioned ignition or flame-sensing electrode stops the boiler relighting. Cleaning or replacing it means opening the boiler.
Technical note: when replacing the electrodes on a Vaillant ecoTEC, the burner door graphite gasket must always be renewed at the same time to maintain a safe, gas-tight combustion seal.
Gas Safe engineer only Low gas pressure at the boiler, or a faulty gas valve, can stop it relighting. Testing gas pressure and working on the gas valve must only be done by a Gas Safe registered engineer.
Gas Safe engineer only A blocked or damaged flue, or a problem with the air intake, can put the flame out. Do not try to clear or adjust the flue yourself.
Gas Safe engineer only
Always check your engineer is on the Gas Safe Register.
If you smell gas, do not reset the boiler. Turn off the gas at the meter if you can, open the windows, do not use switches or naked flames, leave the property and call the National Gas Emergency Service on 0800 111 999.
From the job: ecoTEC Plus 832, F.29 a few times a week
ecoTEC Plus 832 throwing F.29 a few times a week, usually halfway through heating up. The ignition electrode was worn down and sooted. Fitted a new one with a new seal and checked the combustion afterwards. Cost to the customer: £198 + VAT.
Expert notes by Jamie Watkins, Gas Safe registered engineer (Gas Safe ID 6115118), Homecure Plumbers – Gas Safe Reg 505421
Repairs from £95 + VAT for the first hour, including diagnosis (or a fix if it can be done within the first hour with no parts needed), no callout charge.
Typical costs, fitted: electrode replacement from £198 + VAT; gas valve replacement from £288 + VAT. Subject to diagnosis; prices vary depending on boiler model and job complexity. Prices apply during office hours; parking or the congestion charge may be added.
Book a Vaillant boiler repair or call 0203 504 4000.
Press the reset button once and wait for it to restart. Check your manual for your model. If F.29 comes back, do not keep resetting it.
Yes. Glow-worm uses the same code for the same fault: the flame has gone out and the boiler could not relight. See our Glow-worm fault codes.
Sources: Vaillant: boiler fault codes · Gas Safe Register