If your Worcester boiler is not turning on, it’s either getting no power, so the display is blank, or it has power but isn’t getting a call for heat. Most of the time the fix is a simple check: the fused spur, the timer, the thermostat, the gas supply or a frozen condensate pipe. When an older Worcester keeps refusing to start, though, a new Worcester Bosch boiler is usually the better long-term answer, both for efficiency and for repair bills.
We’re Clever Energy Boilers, Gas Safe registered (no. 554138) and accredited Worcester Bosch installers based in Bingley. In 15 years we’ve completed more than 25,000 installations across Yorkshire, the North West and the Midlands. Below you’ll find Worcester’s own checklist, a reset table for each Greenstar model and the point where it becomes an engineer’s job. If your boiler has power but won’t light, our guide to a boiler not firing up may help too.
Why is my Worcester boiler not turning on?
Look at the display first, because it splits the problem in two:
| What you see | Likely cause | Who sorts it |
|---|---|---|
| Blank display, switch next to the boiler off | Fused spur switched off, or an RCD tripped at the consumer unit | You |
| Blank display, power reaching the spur | Internal fuse blown, or a failed PCB or display | Gas Safe engineer |
| Display on, boiler doesn’t respond | Timer off, or the room or cylinder thermostat set too low | You |
| Display on, A21 showing | Lost signal from a wireless thermostat, often flat batteries | You, then an engineer if it persists |
| Flame code such as EA or 227 | No gas reaching the boiler | Check the meter, then an engineer |
| Stopped in freezing weather | Frozen condensate pipe | You, at ground level only |
| Gauge below 1 bar | Low pressure | You, by topping up |
Wireless controls catch a lot of people out. Our Worcester A21 fault code guide covers the lost signal, and a gas supply problem usually shows as EA or 227. On exposed homes in the hills above Keighley and Haworth, a frozen condensate pipe is one of the most common reasons a boiler stops in winter, and our Worcester D5 fault code guide explains the drainage side. For any other code, start with our Worcester boiler error codes guide.
What does Worcester say to check when the boiler won’t turn on?
Worcester’s own manuals suggest working through these before anything else:
- Is the power on? Check the fused spur, and that nothing has tripped at the consumer unit.
- The programmer or timer should be on and set to a heating or hot water period.
- Room and cylinder thermostats mustn’t be set too low. Turn the room thermostat up a few degrees to see if the boiler responds, and if it’s wireless, change the batteries.
- Cold mains turned on.
- Pressure between 1 and 1.5 bar when the boiler is cold. If it’s lower, see our guide on how to repressurise a boiler.
- Other gas appliances working, and credit on a prepayment meter.
If an RCD trips again as soon as you reset it, leave it off and get it checked rather than forcing it back on.
How do I reset my Worcester boiler?
Once you’ve been through the checklist, try one reset. The method depends on your Greenstar model:
| Worcester model | How to reset it |
|---|---|
| Greenstar i | Hold the reset button for about 5 seconds |
| Greenstar CDi range | Press the reset button for 3 seconds |
| Greenstar 4000 | Press the arrow keys until “Reset” shows on the display |
| Greenstar 8000 Style | Press the arrow keys until “Reset” shows on the display |
| Greenstar 8000 Life | Follow the reset steps in your user manual |
| Greenstar 2000, Si and other models | Follow the reset steps in your user manual |
A few rules apply whichever model you have:
- Reset once. If the boiler locks out again, the fault is still there.
- When the boiler stopped in freezing weather, thaw the condensate pipe first, at ground level only and with warm water, never boiling. Our guide on how to defrost your condensate pipe shows you how.
- Never take the casing off to look for a reset button or a fuse.
Is a Worcester boiler that won’t turn on dangerous?
Usually not. A boiler that won’t start is more of a nuisance than a danger. The exception is a smell of gas: open the windows, don’t touch any electrical switches, turn the gas off at the meter and call the National Gas Emergency Service on 0800 111 999.
When should I get a Gas Safe engineer for a Worcester that won’t turn on?
Once you’ve been through the checklist, reset once and the boiler still won’t start, or the display stays blank with power reaching the spur. An internal fuse, a wiring fault, a failed display or a failed PCB all mean opening the boiler, and that’s for a Gas Safe registered engineer only.
A fuse or wiring repair is usually the cheaper end, though the engineer will need to find out why the fuse blew. A new PCB is the expensive one, at roughly £250 to £500 for parts, and some guides put it at £300 to £600. Our boiler PCB faults guide has more on control board problems.
Is it time to replace your Worcester boiler?
A dead PCB on a boiler more than 8 years old is the classic point to replace rather than repair. You’d be putting an expensive part into a boiler that’s already less efficient than a new one, and other parts of the same age tend to follow.
It’s worth getting a quote for a new boiler if:
- Your Worcester is over 8 years old
- An engineer has quoted for a new PCB
- The boiler keeps cutting out or needing resets to get going
- You’ve had more than one breakdown in the last year
We offer boiler replacement at fixed prices, and a new boiler from us can come with a long, market-leading warranty through Clever Energy. If you’d rather pay monthly, see our boiler finance options. Our guides on when your boiler needs replacing and how much a new boiler costs will help you weigh it up.
Worcester boiler not turning on FAQs
Where is the reset button on my Worcester boiler?
It depends on the model. The Greenstar i and CDi range have a reset button you hold or press, while on the Greenstar 4000 and 8000 Style you use the arrow keys until “Reset” shows. For the 8000 Life and other models, check your user manual.
Why won’t my Worcester turn on after a power cut?
Start with the fused spur and the consumer unit, then check the timer and thermostat haven’t lost their settings. If the display stays blank with power reaching the spur, an internal fuse or the PCB may have failed, and that’s for an engineer.
Why is my Worcester boiler display blank?
Usually no power is reaching it. Check the fused spur and the consumer unit first, and if both are fine, the internal fuse, the PCB or the display may have failed.
Why is my Worcester on but not firing?
It’s probably not getting a call for heat. Check the timer, the room and cylinder thermostats and the batteries in any wireless controls, then the gas supply, the pressure and the condensate pipe.
How many times can I reset my Worcester boiler?
Once. If it locks out again after a single reset, the fault is still there, and a Gas Safe registered engineer needs to find the cause.
Get a new Worcester Bosch boiler with Clever Energy
We fit Worcester Bosch boilers in Bingley, Bradford, Leeds, Keighley, Halifax, Huddersfield and across Yorkshire, as well as the North West and the Midlands. As accredited Worcester Bosch installers, we can help you choose from the current range. See our Worcester Bosch boiler installation page, get a fixed price online in a few minutes, or request a callback.