T013_F: Flame Lost After Established
Status
Flame loss is not a critical fault per say. However if repeated continuous failures occur, the system will go into a one-hour lockout.
Description
After a successful ignition trial where the flame was, in fact, sensed, the flame signal reduced or went away. This can happen after any successful proof of ignition.
Expected Operation
When the flame that was proven is lost, the blower will be energized if it weren't already and will run for the blower off period of 90 seconds. The inducer will continue to run and the ignition sequence will again take place. If the "T013_F Flame Lost after Established" alert occurs 4 times in a single call for heat it will display A114_F: One Hour Lockout: Flame Lost Failure.
If the IFC experiences five flame losses (4 re-cycles) within a single call for heat, it will complete a post-purge and blower off delay before proceeding to a one-hour soft lockout at which time alarm; “A114_F One-hour Lockout: Flame Lost Failure” is declared.Upon exiting the lockout, the alarm shall be cleared.
If the alert; “T013_F Flame Lost after Established” gets set and is followed by failed ignitions (alarm; “A011_F Failed Ignition”), the furnace control shall not clear the strike counter for the lost flame until either:
- The IFC enters a one-hour lockout (e.g. due to four successive ignition failures or five flame losses after being established),
- Heat call has been removed, or
- Power has been reset.
Cause
The most common cause for flame sense to weaken is a dirty or corroded flame sense rod. A loss of gas supply from either a failed gas valve or from the source, such as running out of LP gas. An undersized or restricted gas line can allow the furnace to fire fine and whence the volume runs out it can cause the flame to reduce.
Solution
Clean flame sensor using steel wool or a crispy dollar bill. Do NOT use sandpaper or emery cloth to clean flame sensors. Check mounting of the flame sense rod, ensure proper furnace grounding, check for undesirable flame patterns.
Verify gas supply line is large enough, external regulator is working correctly, or no gas safety check valves have been activated.
