Why boilers lock out
Modern boilers have safety systems that shut the boiler down and lock it out when they detect a problem, rather than carry on running unsafely. Common triggers are low system pressure, a failed ignition, a frozen condensate pipe in cold weather, or a sensor reading something out of range. The boiler usually displays a fault or error code to indicate what tripped it.
The lockout is the boiler protecting itself and your home. A reset tells it to try again, which works if the underlying issue has cleared, and does nothing lasting if it has not.
How to reset it
First, quickly check the obvious: is the pressure gauge in the normal band (around 1 to 1.5 bar cold)? If it is low, top it up with the filling loop first, as low pressure will just trip it again. In very cold weather, check the outside condensate pipe is not frozen, covered in frozen condensate pipe.
To reset, press and hold the reset button on the boiler, usually marked with a flame symbol or the word reset, for a few seconds until the boiler begins its ignition sequence. If your boiler has no obvious reset button, the manual will show how; some reset via the dial or display. The boiler should fire back up within a minute.
The rule: reset once, maybe twice, not endlessly
This is the part that matters. Resetting a boiler once, or twice, to clear a one-off glitch is fine. Repeatedly resetting a boiler that keeps locking out is not, because the lockout is there for a reason and you may be overriding a genuine fault, which at worst can be a safety issue.
A sensible rule: if a boiler locks out again shortly after a reset, or you find yourself resetting it more than a couple of times, stop and get it looked at. There is a fault the reset is not fixing.
When to call an engineer
Call a Gas Safe engineer if the boiler will not reset at all, locks out repeatedly, shows a fault code you cannot clear, or you ever smell gas (in which case turn off the gas at the meter, open windows, do not touch electrics and call the gas emergency line). LMB covers boiler faults across Bridgend and South Wales. Message Lloyd with the fault code showing and he can often tell you what it means before a visit.
