A flame safeguard steps the burner through prepurge, ignition, pilot and main flame trials, run and postpurge, checking interlocks at each stage. When the flame signal is lost it must close the fuel valves within its flame failure response time, typically 4 seconds or less, and lock out if the start sequence fails. On residential oil burners the same job is done by a primary control.
Flame safeguard is showing a lockout on main flame trial, the pilot proved but the main valve never opened.
Write down the lockout code and sequence step before you reset; the code clears and the clue goes with it.
Also heard as
- FSG
- programmer
- flame safeguard control
Related terms
Flame scanner
The sensor that proves to the burner control that a flame is actually present.
Purge
Blowing air through the furnace and flue before ignition or after shutdown to clear out unburned fuel.
Trial for ignition
The short, fixed time window during which the burner control must see a pilot or main flame before it locks out.
Lockout
A safety shutdown that holds the burner off until someone presses a manual reset.
BMS
Burner management system: the safety controls that handle purge, ignition, flame proving and trips on larger boilers.