Boiler Not Working FAQs
Common reasons why your boiler isn't working and simple fixes to try before calling an engineer.
5 questions answered by our Gas Safe engineers
My boiler has no power — what should I check?
Check the fuse in the fuse box for the boiler circuit. Check the plug if the boiler is socket-powered. Ensure the boiler is switched on.
My boiler fires up but the radiators stay cold — why?
Common causes: the pump is faulty, there's air in the system (bleed radiators), the diverter valve is stuck (combi boilers), or the thermostat is set incorrectly.
My boiler is on but there's no hot water
On a combi boiler, this often indicates a faulty diverter valve (it's heating radiators instead of hot water). Turn off heating and test hot water only. Call an engineer if the issue persists.
My boiler keeps switching itself off
This is called 'short cycling' and can be caused by overheating, low pressure, a faulty thermostat, or restricted water flow. Check pressure first. If it continues, call an engineer.
My boiler displays a fault code — what do I do?
Note the fault code and check the manufacturer's manual or our error codes FAQ. Many codes indicate low pressure (re-pressurise) or ignition failures (reset the boiler). If the fault persists, call an engineer.
Still have a question?
Our Gas Safe engineers are happy to answer any boiler questions. Call or message us.
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