The reset button clears a fault the boiler's flagged and gives it another go, it doesn't fix whatever caused the fault in the first place. If your boiler's not working again straight after a reset, or won't stay on for more than a few minutes, that's a sign of a real fault rather than a one-off glitch, and resetting again usually won't change the outcome.
This page covers what a reset actually does, when it's worth trying, and what it means if it doesn't hold.
How to tell if hot water is not working?
Run a hot tap and give it a minute or two: if the water stays cold throughout, rather than starting warm and fading, that usually points to the boiler itself rather than the tap or the pipework. Check whether your heating's still working while this happens, since that narrows down whether the fault is central or specific to hot water.
Heating working but no hot water, or the reverse, usually means a diverter valve or thermostat fault rather than something a reset will clear permanently.
How to unstick a diverter valve?
A stuck diverter valve isn't something to free up yourself. It involves draining part of the system and working inside the boiler casing, and getting it wrong can cause bigger problems or void your warranty. If you suspect a stuck diverter valve, because hot water and heating seem to be interfering with each other, radiators staying cold while taps run hot or the other way round, that's a job for a Gas Safe registered engineer.
Resetting the boiler won't unstick a valve. If the symptom comes straight back after a reset, that's actually a useful sign for the engineer, since it points them toward the valve rather than a different fault.
How to reset central heating system?
Most boilers have a reset button on the front panel, sometimes behind a small flap, marked with a reset symbol or the word "reset". Press and hold it for the time stated in your manual, usually a few seconds, then wait for the boiler to restart and check the display or pilot light.
Only reset a boiler once. If it fails again shortly after, resetting repeatedly can mask a fault that needs a proper look, and on some models can trigger a lockout that needs an engineer to clear.
Questions people ask
What happens if you bleed a radiator with the heating on?
You can bleed a radiator with the heating on, but it's easier and safer with it off, since the water inside will be hot rather than scalding. Have a cloth and a container ready to catch the small amount of water that escapes, and close the valve as soon the air stops hissing and water starts to come through.
How long does boiler repair take?
Many straightforward repairs are completed in a single visit, often within an hour or two, if the part needed is one the engineer carries with them. A repair that needs an ordered part can take longer. The specialist you're matched with can give you a realistic estimate once they've seen the fault.
How quickly can an engineer come out in Surrey?
That depends on the engineer's current workload and how urgent the job is. Flagging a job as an emergency, no heating or hot water at all, generally gets a faster response than a routine fault. Tell us what's happened and we'll pass it to a local specialist who can give you a realistic timeframe.
Do I need to be home for boiler repair?
Yes. An engineer needs access to the boiler itself, and usually needs to ask about what's happened and test the system before and after the repair, so someone needs to be present for the whole visit. If you can't be there, another adult who knows the history of the fault can stand in, as long as they can let the engineer in and answer their questions.
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