Boiler Has No Power? Why the Display Is Blank and What to Do
A boiler with a blank display and no lights isn't getting electricity to its controls. The safe checks you can do (power cut, fuse box, fused spur, controls) and the faults inside the boiler that need a Gas Safe engineer.
If your boiler has no power and the display is blank, electricity isn't reaching its controls. Check in this order: whether the rest of the house has power, whether a breaker or RCD has tripped in the consumer unit, whether the switch on the fused spur next to the boiler is on, and whether the fuse in that spur has blown (most boilers use a 3 amp fuse, but check the manual or data badge). Reset a tripped breaker once only. If it trips again, or the spur fuse blows again straight away, stop, because something in the boiler or its wiring is faulty. If the supply to the spur is fine and the boiler is still dead, the fault is inside the boiler, usually an internal fuse, the printed circuit board or water damage from a leak, and that needs a Gas Safe registered engineer.
Key Takeaways
- A completely blank display means no electricity is reaching the boiler's controls, not a gas problem.
- Check the house power, the consumer unit, the fused spur switch and the spur fuse, in that order.
- Reset a tripped breaker or replace a blown spur fuse once. If it happens again, stop and call an engineer.
- Look for water around or under the boiler. A leak onto the electrics is a common cause of tripping.
- Faults inside the casing, such as internal fuses and the PCB, must be dealt with by a Gas Safe registered engineer.
If your boiler has no power and the display is blank, electricity isn't reaching its controls. That's an electrical problem, not a gas one, and the cause is often outside the boiler: a tripped breaker, a switched-off fused spur or a blown 3 amp fuse. Those you can check safely in a few minutes. If power is reaching the boiler and it's still dead, the fault is inside the casing, and that's a job for a Gas Safe registered engineer. This guide goes through the checks in the order that finds the problem fastest.
What a blank display means
A modern gas boiler uses electricity for its display, control board, fan, ignition and pump. When it's working normally you'll see a screen, a power light or at least a pressure gauge backlight. If there's nothing at all, no lights, no display, no noise when you turn the heating up, the boiler isn't receiving mains power or can't use it.
That's different from a boiler with a working display that shows a fault code, a flashing light or a lockout symbol. If you can see a code, the boiler has power, and our guide to boiler error codes is the better place to start.
Safe checks, in order
Does the rest of the house have power?
Try a light and a plug socket. If the whole house or street is off, it's a power cut. The boiler will come back when the power does, although the timer may have reset.
Check the consumer unit
Open your fuse box and look for any switch in the off or down position. The boiler circuit is often labelled heating, boiler or sockets. Reset a tripped breaker or RCD once. If it trips again straight away, leave it off; there's a fault somewhere on that circuit.
Find the fused spur and check the switch
Most boilers are wired to a fused spur: a switched plate on the wall near the boiler, under it, or in the airing cupboard. It's often labelled boiler or CH. Make sure the switch is on and the neon light, if it has one, is lit. These switches get knocked off during decorating or when someone's looking for a light switch.
Check the fuse in the spur
Switch the spur off, then open the small fuse carrier on the front with a flat screwdriver. Replace the fuse with a new one of the same rating. Most boilers use a 3 amp fuse, but check the boiler manual or the data badge. Never fit a larger fuse. Switch back on and see if the display returns.
Check any external controls
Some systems route power through a wiring centre, a programmer or a frost thermostat. If the boiler display is on but it won't fire, the controls are the next suspect. If the display is still blank, move on.
Look for water
Check under and around the boiler, the pipes below it and the spur itself for drips, damp patches or rust marks. Water on the electrics is a common reason for a blown fuse or a tripping RCD.
If the boiler keeps tripping the electrics
A breaker or RCD that trips every time the boiler starts, or a spur fuse that blows again as soon as you replace it, means there's a fault the protection device is doing its job on. Common causes:
- A leak inside the boiler dripping onto the pump, the fan or the control board. See our guide to a boiler leaking water.
- A failing pump or fan motor with an earth fault, which may only trip when that part starts up.
- Damp in the wiring, often where a boiler sits on an outside wall or in a loft or garage.
- A fault in the external controls such as a wiring centre, zone valve or wired thermostat on the same supply.
Repeated resetting doesn't fix any of these, and it can damage the circuit board.
Faults inside the boiler
If power is reaching the fused spur and the boiler is still dead, the fault is inside the casing. The usual suspects are:
- An internal fuse on the printed circuit board (PCB). It rarely blows without a reason, so the engineer will look for what caused it.
- The PCB itself, damaged by a power surge, water or age.
- The display or a loose connection between the display and the main board, where the boiler may still be running but can't show anything.
- Wiring damage from overheating, vermin or water.
On an older boiler, a failed PCB can be the point where repair and replacement get close in cost. Our guide to how long boilers last helps with that decision.
Display on, but the boiler does nothing
If the lights are on but you get no heating or hot water, the boiler has power and the cause is something else. Check:
- the pressure gauge: most boilers stop below about 1 bar, see how to repressurise a boiler;
- the timer and room thermostat, especially after a power cut, which can reset the programmer;
- for a lockout or fault code, try one reset as described in how to reset a boiler;
- whether your gas hob works. If nothing on gas works, read gas not working in the house.
Our main guide to a boiler that isn't working covers these in more detail.
While you wait for an engineer
- Leave the boiler switched off at the fused spur if anything tripped, blew or looked wet.
- If you have a hot water cylinder with an immersion heater, you can usually still get hot water from that.
- Use portable electric heaters sensibly in the rooms you need, on their own sockets.
- In freezing weather, keep the house above freezing where you can and know where your stopcock is in case a pipe freezes.
- Note the boiler make and model from the badge under the front cover or on the side, and anything the display did before it went blank. It saves time on the visit.
When to call us
Call a Gas Safe registered engineer if the boiler is still dead with power at the spur, if the breaker or fuse trips again, if there's water, a burning smell or scorch marks, or if you're not comfortable checking the spur. We carry out boiler repairs across London, from blown fuses and failed PCBs to leaks that have reached the electrics, and we can tell you honestly if an older boiler is worth repairing. Our labour is £95 an hour, the £60 call-out is waived when the job runs over 2 hours, and we confirm the price before any work starts.
Boiler still dead?
Tell us the make and model and what you've checked so far. We'll confirm the price before we start.
📞 Call 020 7870 3200Or see our boiler repair service and pricing.
Frequently Asked Questions
Why does my boiler have no power?
The most common causes are a power cut, a tripped breaker or RCD in the consumer unit, the fused spur switch next to the boiler being turned off, or a blown fuse in that spur. If the supply to the boiler is fine, the fault is inside the boiler, usually an internal fuse, the printed circuit board or water getting onto the electrics.
Where is the fuse for my boiler?
Most boilers are supplied from a fused spur, a switched outlet on the wall near the boiler or in the airing cupboard, often labelled boiler or central heating. The fuse sits in a small carrier on the front of the spur. Boilers also have internal fuses on the circuit board, but those are behind the casing and should only be checked by a Gas Safe registered engineer.
What size fuse does a boiler need?
Most domestic boilers use a 3 amp fuse in the fused spur, but always check the installation manual or the data badge on the boiler. Never fit a bigger fuse to stop it blowing. A fuse that blows repeatedly is protecting you from a fault.
Why does my boiler keep tripping the electrics?
Repeated tripping usually means water is reaching an electrical part, often from a leak inside the boiler or from condensation, or that a component such as the pump or fan has developed an earth fault. Leave it switched off at the spur and have it checked.
Can I reset a boiler with no power?
No. The reset button only works when the boiler has power and is showing a lockout. With a blank display there is nothing to reset. Restore the power supply first, then reset the boiler if it shows a fault code.