Boiler Screen Blank Or Dead

What's happening?

A boiler with a blank display and no lights is not getting power, or its own board has failed. Which one it is has an easy first test: if the display is dark and nothing comes on, find out whether the boiler is being fed. Most boilers plug into the house wiring through a fused spur, a switch and fuse beside the boiler or in a nearby cupboard. That switch can be knocked off. The fuse inside it can blow. The circuit it lives on can trip at the fuse board. Past those, the boiler has its own internal fuse and a circuit board, and when either fails the display dies. Some boilers also blank the screen after a period of inactivity, and a press of a button wakes it.

What usually causes it?

• The fused spur switch beside the boiler turned off or its fuse blown
• A tripped breaker or RCD on the circuit that feeds the boiler
• A power cut or surge that has taken out a fuse or board
• A blown internal fuse on the boiler's circuit board
• A failed circuit board or display
• A fault in the supply cable or the timer or programmer that switches the boiler

Is it dangerous?

No for a dead display. If the boiler or switch is hot, smells of burning or trips again straight away, switch it off at the spur and leave it off. That is an electrical fault.

Can I fix it myself?

Press a button on the display to rule out a sleep mode. Check the switch beside the boiler is on and the fuse board has nothing tripped. Try resetting a single tripped breaker once. If a socket on the same circuit also has no power, the fault is the circuit. Do not replace the fuse with a higher rating and do not open the boiler.

When should you call a heating engineer?

Call an electrician if the spur or breaker keeps tripping with the boiler switched off, or if other sockets or lights are dead. Call a Gas Safe registered heating engineer if the circuit is live and the boiler is still dark, because the board or fuse inside is theirs.

What will the heating engineer actually do?

• Test that the supply to the spur and the boiler is live and the protection correct
• Check the spur fuse and the boiler's internal fuse
• Test the board and display for a fault
• Replace the failed fuse, board or display, matching the make and model
• Check the programmer and thermostat wiring that switch the boiler
• Confirm the boiler starts and runs a full heating and hot water cycle

Who fixes this

• Boiler repair
• Heating not working

Questions people ask

Sources & References

1. GOV.UK: Approved Document P, electrical safety
2. Vaillant: most common boiler problems
3. Vaillant: how to reset a boiler