Dunkirk D249 Series Commercial Boiler - Manual (Page 8)

Gas Valve Sensing
If either or both the pilot and main gas valves are sensed
to be on when commanded to be off, or if no voltage
appears at gas valve output which was commanded on,
control will shut off all outputs and enter either “soft” or
“hard” lockout state. Main valve is interlocked with the pilot
valve and voltage can only be detected on main valve when
pilot valve is energized. Control locks out the first time
as “soft” lockout, then retries after 5 minutes and enters
“hard” lockout state. Lockout should be manually reset as
described in “Lockout.”
Flame Present With Gas Off
If flame is sensed for longer than 2 seconds during a period
when gas valve should be closed, control will enter lockout.
Power Interruptions
Power interruptions less than 0.15 seconds will not
cause control to interrupt heat sequence while power
interruptions over 0.25 seconds will cause the control
to reset lockout and ignition trial counters. Power
interruptions of any duration will not cause a lockout or any
other operation requiring manual intervention.
Lockout
Controller automatically resets from first lockout in 5
minutes. If second lockout occurs before call for heat is
satisfied, it will require manually resetting by depressing
red button on CSD-1 daughter board. This can be reached
with a pencil through the vent holes. A red LED will also
indicate lockout and can be seen through the vent holes.
SEQUENCE OF OPERATION
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