Advertisement
Burner Program Sequence of Operation
Stand by
Stand-still
status test
(blower)
Call for heat
Water-flow
switch
closed
Ignition
Combination
gas valve
Flame signal
Fan speed
Fan control
Modulation
set point
Phase
0
Sequence
Normal <1s
time
Max.<51s
Phase 0: Stand by
Complete shutdown until the next call
for heat. In this phase both the
combination gas valve and the blower
are not energized.
Phase 1: Stand-still status test (blower)
A call for heat initiates internal blower
sensory communications to confirm
that the blower is truly in stand-still
position. Blower speed measured must
be < 300 rpm within a 51 second
period.
Phase 2: Pre-purge speed test
Controller sends and receives signal to
/ from fan speed controller to verify
maximum rpm of the blower.
Phase 3: Pre-purge
Pre-purge cycle starts within the
pre-programmed timing. Pre-purge
timing is in addition to previous phase
(2). The fan speed must be greater
than and within the range of rpm
requested by the controller.
Pre-purge
Pre-purge
speed test
1
2
3
Normal <1s
0.1s
Max.<51s
Phase 4: Pre-ignition
The ignition spark is initiated and
controlled.
Phase 5: Ignition / safety timing /
flame stabilization
The gas valve opens during the safety
timing period (4.5 secs.). If a flame is
detected, this phase ends immediately
in < 1.5 secs. If the flame is not
established after 3 trials, the burner
will lock out and will require a manual
reset. Controller required time for flame
stabilization.
Phase 6: Burner modulation operation
or calibration
At the end of the flame stabilization
period (4.5 sec.), a release for
modulation occurs and the burner
temperature controller will take over
from the flame safeguard. Forced
shutdown after 24 hours continuous
operation. Automatic calibration may
be initiated by the controller.
Ignition / safety
Burner
Pre-ignition
timing / flame
modulation
stabilization
or calibration
4
5
0.4s
4.5s
Additional Information
Combination
Post-purge
gas valve proof
speed test
and closure test
7
6
8
Normal <3s
Normal <3s
Max.<15s
Max.<15s
Modulation range
Transition
Phase 7: Combination gas valve proof
of closure test
If during the normal operation of the
burner a controlled (or uncontrolled)
shut-down occurs, a complete
mechanical and electrical gas valve
proof of closure test will be performed
by the flame safeguard. After a
successful mechanical and electrical
proof of closure test, the flame
safeguard will expect that the flame is
not present. If, however, the flame
existed for a period of >15 seconds,
the flame safeguard will go into
permanent lock-out.
Phase 8: Post-purge speed test
Both gas valves are closed during this
phase. End call for heat.
Post-purge occurs during the
programmed period.
Phase 9: Additional post-purge
If the fixed high limit trips during
normal operation, the blower will purge
for 15 minutes to cool the heat
exchanger.
Additional
Post-purge
(if initiated)
9
0.15s
67
Advertisement
