Worcester Bosch 224 V: Safety temperature limiter tripped

224 V on a Worcester Bosch boiler means: safety temperature limiter tripped. The water inside the boiler has got too hot, so a safety device has shut it down.

This code applies to Worcester Bosch 8000 Style / 8000 Life. Codes can mean different things on different models, so check the display against your boiler's user manual.

What you can safely check

• Look at the pressure gauge on the front of the boiler. With the heating off and the system cold, it should normally read 1 to 1.5 bar. Low pressure is a common cause of overheating.
• Make sure the valves on your radiators are open, and bleed any radiators that are cold at the top.
• Let the boiler cool down, then press reset once, following your user manual.

When to call an engineer

If it keeps overheating, the usual causes are a failing pump, a blockage (sludge) in the system or heat exchanger, or a faulty sensor. Call a Gas Safe engineer.

Never remove the boiler casing yourself — everything behind it must be handled by a Gas Safe registered engineer. If you smell gas, open windows, turn the gas off at the meter, and call the National Gas Emergency number on 0800 111 999.