If your Vaillant ecoTEC boiler is showing F28 (sometimes shown as F.28), it has tried to light several times and not detected a flame. To protect itself, the boiler locks out and stops trying. You will usually have no heating and no hot water until the fault is cleared.
F28 is one of the most common Vaillant fault codes we see in Maidstone and across Kent, especially in winter. The good news is that a few of the causes are simple to check yourself.
What causes a Vaillant F28 fault?
- No gas reaching the boiler, for example a prepayment meter that has run out of credit, or a gas valve that has been turned off
- A problem with the gas supply to the whole property
- A blocked or frozen condensate pipe, which is common in cold snaps
- A worn or dirty ignition electrode, or a faulty ignition lead
- A faulty gas valve, fan or flame sensor
- A fault on the boiler's printed circuit board (PCB)
Safe checks you can do yourself
- Check another gas appliance, such as the hob. If that will not light either, the problem is the gas supply, not the boiler.
- If you have a prepayment meter, check it has credit and has not tripped.
- Make sure the gas isolation valve under the boiler is open. The handle should run in line with the pipe.
- In freezing weather, look at the plastic condensate pipe where it leaves the house. If it is frozen, pour warm (not boiling) water along it to thaw it.
- Press the reset button once and wait. If the boiler lights and stays on, keep an eye on it.
Do not keep pressing reset over and over. If the boiler locks out again, there is a fault that needs an engineer.
When to call a Gas Safe engineer
If F28 keeps coming back, or your other gas appliances work fine, the fault is inside the boiler. Testing gas pressures, the gas valve, the electrode and the PCB must be done by a Gas Safe registered engineer. Never remove the boiler casing yourself.
If you can smell gas, do not touch any switches. Turn off the gas at the meter, open windows, leave the property and call the National Gas Emergency Service on 0800 111 999.
Is it worth repairing?
Most F28 faults are fixed with a single part such as an electrode or a sensor, and are well worth repairing. If your boiler is over ten years old and failing often, we will tell you honestly whether a replacement makes more sense.
Phoenix Plumbing & Heating is a Gas Safe registered team based in Maidstone, covering Kent with 24/7 emergency cover. Call 01622 585169 or book online and one of our engineers will find the fault and give you a clear price before any work starts.