Flame failure, failed ignition trials, low water on a manual-reset cutoff, or a tripped high limit all put a burner into lockout. The control usually stores the cause and the sequence step, which is the first thing a tech reads. Resetting repeatedly without finding the cause floods a cold furnace with fuel, which is how delayed ignitions and explosions happen.
Boiler is locked out on flame failure, read the code before anyone hits reset, I want to know what step it died on.
Reset once, and if it locks out again, find the cause. Three resets is a habit, not a fix.
Also heard as
- safety lockout
- locked out
Related terms
Flame safeguard
The control that runs a burner's start sequence, watches the flame, and shuts the fuel off fast if the flame fails.
Nuisance trip
A safety shutdown or lockout caused by a faulty or marginal device, not by a real unsafe condition.
Trial for ignition
The short, fixed time window during which the burner control must see a pilot or main flame before it locks out.
High limit
A safety control that shuts down the burner if pressure or temperature rises above the normal operating range.