Error F.28

Safety precautions:

1. If you smell gas: stop using appliances, do not operate electrical switches, open windows and doors, turn off the gas at the meter or the emergency control valve if you know where it is, then call the national gas emergency number immediately. Do not attempt internal repairs.

2. If you are unsure or uncomfortable at any point, stop and call a Gas Safe engineer. Do not remove the boiler casing, touch ignition parts, gas valves or PCB connections unless you are qualified.

Initial checks a homeowner can safely do:

1. Note the exact error shown on the display (F.28 / F28 or F.28 lockout) and whether the boiler has attempted to reset automatically. Record any sounds (repeated clicking before lockout).

2. Test other gas appliances (hob, oven, gas fire) to confirm there is gas to the house. If no other appliances work, contact your gas supplier.

3. Check the external gas meter and any emergency shut-off lever to ensure the supply to the property is open. If you are on a prepayment meter check credit and top up if required.

4. Reset the boiler once: follow the boiler manual or the manufacturer’s reset button procedure. Wait for the boiler to attempt ignition. Do not repeatedly press reset; if it locks out again, leave it and proceed with checks.

5. Check boiler pressure. If the pressure gauge is below about 0.8–1.0 bar, the boiler may refuse to fire. If you know how, repressurise the system using the filling loop to about 1.0–1.5 bar, then try a single reset and observe.

6. Inspect the external condensate pipe (usually a small plastic pipe running to outside drain). In freezing weather it can block; if frozen, thaw it by pouring warm (not boiling) water over the exposed section or using a warm cloth. Do not use open flames. Insulate it after thawing.

7. Visually check the flue terminal and air intake outside for obvious blockages (bird nest, debris, snow) and clear any obstruction safely from outside. Ensure nothing is covering the air inlet.

8. Ensure the external gas service cock to the boiler (usually a yellow-handled valve on the incoming gas pipe) is turned to the open position if you know where it is.

Specific diagnostic and next steps:

1. After addressing pressure, condensate or obvious supply issues, reset the boiler once and watch/listen: if you hear the ignition transformer trying to spark (repeated clicking) but no flame is established, this suggests an ignition electrode or flame sensing problem or a gas flow issue (valve or supply). If there is no clicking, the control/ignition circuit or gas valve may not be being energised.

2. If other gas appliances worked and you have adequate system pressure but F.28 returns, do not attempt internal repairs. Note whether the fault appears immediately or after a few seconds of ignition attempts and whether any other error codes appear.

3. Record the boiler model, serial number, date, precise fault code, and the steps you have taken (pressure reading, condensate thawed, other appliances tested, reset attempts). This information speeds up an engineer’s diagnosis.

When to call a professional and what they will do:

1. Call a Gas Safe registered engineer if the F.28 persists after your safe checks, if you smell gas, if you suspect a frozen or blocked internal component, or if you observe electrical faults. Any replacement or adjustment of the gas valve, ignition electrode, ignition lead, flame sensor, wiring or PCB must be done by a qualified engineer.

2. The engineer will carry out safe gas-pressure checks, test the incoming gas pressure, check the gas valve operation, inspect/replace ignition electrodes and leads, test flame detection, check wiring and the PCB, and clear or replace blocked condensate components if needed. They will also run safe ignition trials and reset the fault correctly.

Final notes:

1. Do not attempt to dismantle or replace ignition components, the gas valve, or internal wiring yourself. That work is regulated and dangerous if performed incorrectly. Use a Gas Safe registered engineer for any internal boiler repairs.

2. After repair, request a written report of work done and ensure the boiler is tested and left operating normally. Keep a record of the fault, what you tried, and the engineer’s findings for warranty or future reference.