18
10) PILOT TRIAL (1st safety time)
The control turns on the pilot flame by energizing terminal 17. The MAIN direct output (terminal
18) is also energized for systems that implement direct light-off of the main flame during pilot.
The control doesn't check for flame during this phase as the flame may not be fully established.
11) PILOT TRIAL (1st safety time)
The ignition transformer is turned off. The pilot flame signal is proven during this phase. Failure
to “see” a flame results in a lockout.
12) MAIN TRIAL (2nd safety time)
The main fuel valve (piloted) output (terminal 19) is energized to light-off the main flame. Flame
signal must be present during this phase.
13) MAIN TRIAL (2nd safety time)
The pilot output (terminal 17) is turned off during this phase. Flame signal must remain present.
14) RELEASE TO MODULATION
After successfully establishing flame, the control proceeds to relinquish modulation control to the
boiler management system. Flame signal must remain present. Terminal 20 is energized.
15) MOVE TO SHUTDOWN
Move to shutdown occurs when the load demand has been satisfied and the RECYCLE LIMIT
(terminal 5) is open. This forces the control to close the main fuel valves by de-energizing
MAIN_direct (terminal 18) and MAIN_piloted (terminal 19) outputs. The combustion air blower
remains on for post-purge. Flame afterburn is allowed during this phase
16) SHUTDOWN
The control proceeds to purge the combustion chamber for a period of time (length of post-purge
is based on the control series installed). Then it proceeds to the MINIMUM (low-fire) position
and later to the ECONOMY (closed) position. After successfully completing a post-purge cycle,
the control turns off the combustion air blower. Any flame afterburn is expected to be completed
at the completion of post-purge.
17) LOCKOUT
The control proceeds to a lockout state when it detects an internal or external fault condition. The
reset button and remote reset terminal can be used to exit the lockout state. However, the control
will revert to lockout if the fault condition is not rectified.
