Error LC

Safety precautions:

- If you smell gas, do not operate the boiler or any electrical switches: get everyone out, call the gas emergency number immediately, and call a Gas Safe engineer.

- If you suspect carbon monoxide (headaches, dizziness, soot, yellow pilot flame), turn off the appliance, ventilate the area, leave the property and get an emergency engineer.

- Do not open the boiler casing or attempt to adjust gas components or internal electronics yourself. Working on gas appliances or live electrical parts must be done by a Gas Safe registered engineer.

Initial checks a homeowner can do:

1. Note when LC appears and what the boiler was doing (heating on, DHW on, just came back from a reset). This helps the engineer diagnose later.

2. Check boiler pressure on the gauge. If pressure is below about 1.0 bar (cold) the system may be causing faults — repressurise to around 1.0–1.5 bar following the manual instructions if you are comfortable doing so.

3. Check other gas appliances (hob, gas fire) to confirm gas supply is present. If no gas supply to the property, contact your gas supplier.

4. Check the condensate pipe (external plastic pipe) for freezing or blockages in cold weather. If frozen, thaw with warm (not boiling) water or a warm cloth. Clear any visible blockage from the outlet.

5. Check the mains electrical supply and fuse spur to the boiler. Ensure the boiler is receiving mains power and the isolator isn’t turned off.

6. Inspect for visible water leaks around the boiler and ensure all radiator and boiler valves are open.

Specific diagnostic and fix steps to try safely:

1. Power-cycle/reset: Turn the boiler off at the boiler’s on/off switch or the isolator/fuse spur. Wait 30–60 seconds and turn it back on. If the boiler has a RESET button, follow the user manual instructions to reset once only. If LC clears, operate the heating and hot water and watch for reappearance of LC. If it does not return, monitor but no further action may be needed.

2. Repressurise (if pressure low): With the boiler cold and following the user manual, use the filling loop until the gauge reaches about 1.0–1.5 bar, then close the loop and restart the boiler. If pressure was the issue and LC clears, monitor pressure over days — a continuing drop indicates a leak or component fault requiring an engineer.

3. Condensate pipe: If blocked or frozen, clear or thaw it and then reset the boiler. A cleared condensate problem may stop repeated restarts that triggered LC.

4. Check thermostats/timers: Make sure room stat/timers or external controls are not rapidly switching the boiler on and off. Replace batteries in wireless controls and check wiring where accessible.

5. Record events: If LC returns, note the sequence (e.g., boiler tries to start, flames appear then fail, or immediate lockout) and how often. This information is useful for the engineer.

When to call a professional:

- If LC returns after a basic power-cycle and simple checks, contact a Gas Safe registered engineer. Repeated lockouts often indicate ignition/flame detection, PCB, thermistor, pump or gas valve issues that require specialist diagnostics and safe repairs.

- If you cannot repressurise the system, find a leak, or the pressure keeps dropping, call an engineer.

- If there are any signs of gas smell, carbon monoxide, or electrical faults, call emergency services and a Gas Safe engineer immediately.

Final note: LC is a protective response and clearing it by power-cycling is safe as an initial step, but because it signals repeated fault conditions you should arrange professional inspection if the error recurs. Do not attempt internal electrical or gas repairs yourself.