🔍 Why Is My Boiler Not Working?
A boiler that stops working is one of the most stressful home emergencies — especially in cold weather. The good news is that most boiler faults have common causes that a Gas Safe engineer can diagnose and fix quickly.
Here are the most common reasons your boiler has stopped working:
| Symptom | Likely Cause | Urgency |
|---|---|---|
| No heating or hot water | Frozen condensate pipe, pressure loss, or faulty diverter valve | Same day |
| Boiler fires but goes off | Faulty thermocouple, flame sensor, or gas valve | Same day |
| Boiler won't ignite | No gas supply, faulty ignition, or blocked burner | Urgent |
| Error code showing | Depends on code — see our error code guides | Varies |
| Leaking boiler | Faulty pressure relief valve, pump seal, or heat exchanger | Urgent |
| Strange noises | Kettling, pump failure, or trapped air | Book soon |
🚨 Check These First Before Calling
1. Check the pressure gauge
Your boiler pressure should be between 1 and 1.5 bar. If it's below 1, the boiler may have locked out. You can repressurise most boilers yourself using the filling loop — check your manual or call us for guidance.
2. Check your thermostat
Make sure the thermostat is set above the current room temperature. Check the batteries if it's wireless.
3. Check the timer/programmer
Has the clock changed? Check your heating schedule is set correctly.
4. Check the fuse box
A tripped RCD can cut power to your boiler. Check the consumer unit for any tripped switches.
5. Check other gas appliances
If your hob or gas fire also doesn't work, the issue may be with your gas supply. Call National Gas Emergency on 0800 111 999 immediately.
🌡️ Frozen Condensate Pipe — Common in Winter
In cold weather, the most common reason a boiler stops working is a frozen condensate pipe. This is the white plastic pipe that usually exits through an external wall.
Signs your condensate pipe is frozen:
- Boiler shows an error code (Worcester EA229, Vaillant F28/F29)
- Gurgling sound from the boiler
- Boiler locks out in cold weather
How to thaw a frozen condensate pipe:
- Pour warm (not boiling) water over the pipe
- Use a hot water bottle against the pipe
- Once thawed, press the reset button on your boiler
💷 How Much Does a Boiler Repair Cost in London?
Boiler repair costs in London vary depending on the fault and parts required:
| Repair Type | Typical Cost | Time |
|---|---|---|
| Diagnosis / call-out | £80 – £110 | 1 hour |
| Pressure/condensate fix | £90 – £150 | 1 hour |
| PCB replacement | £200 – £400 | 2-3 hours |
| Gas valve replacement | £200 – £350 | 2-3 hours |
| Diverter valve | £150 – £300 | 2 hours |
| Heat exchanger | £300 – £500 | 3-4 hours |
| Full boiler replacement | £1,500 – £2,500 | 1 day |
At FE Maintenance we provide a fixed price quote before any work begins — no hidden charges.
Frequently Asked Questions
📚 Related Guides
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