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Modulation Output
The modulation output subsystem uses as its input either the
modulation rate provided by the Internal Demand/Rate
Selector, which possibly is limited by a Rate Limit function, or
it uses a fixed modulation rate indicated by the burner control,
such as during prepurge or lightoff.
Fig. 4 in “Demand and Rate” on page 19 shows these
sources. The modulation output subsystem sends a rate to
one of three outputs: a fan speed control that uses a PWM
output and tachometer feedback, a 4-20 mA analog signal, or
a 0-10 V analog signal.
When the installer selects a fan speed system, rate
parameters will be specified in RPM without regard to the
burner capacity represented by a particular RPM. When one
of the analog outputs is chosen, rate parameters will be
specified as percentages, and in this case, the installer is
thinking of this as a percent of burner capacity.
Common Modulation Parameters
These parameters are needed whenever any type of
modulation is used. They are listed in the order they would be
used in a burner firing sequence.
Table 19. Burner Control Safety Parameters (Continued)
Parameter Comment
Pilot test hold Enable, Disable
This parameter is provided to support the pilot turndown test required by burner standards for
Intermittent and Interrupted pilots. It is ignored if Pilot Type is DBI.
If the Pilot type is Interrupted or Intermittent and this parameter is enabled, the burner control
sequence will hold (forever) at 1 second into the Ignition state.
During Pilot Test Hold, a flame-out timer always starts at zero when the Ignition state is
entered, then counts up toward 15 seconds while flame is off and down toward zero when
flame is on. This timer has a possible effect only during the pilot test: if it ever reaches 15
seconds of accumulated flame out time then a lockout occurs.
The pilot test hold should be enabled prior to entering Ignition, since changes to parameters
may require some seconds to take effect. Similarly, when the hold is disabled the burner
control may remain in the hold condition for a short time.
BLR function
Ignition source
Blower Motor
Internal, External
The Falcon can use either an internal spark generator, an external ignition source driven via
relay contacts that are interlocked with the main valve and powered through the ILK input
terminal. The Falcon operates circuits according to the setting of these parameters; thus if
the igniter circuit that is operated differs from the one actually installed, no ignition will occur.
Run stabilization time MM:SS
During run stabilization the modulation rate is held at the light-off rate and is released for
modulation only after the hold time given by this parameter has expired. If this parameter is
zero then there is no stabilization time.
Postpurge time 0 seconds to 5 minutes (MM:SS)
This parameter sets the burner control’s postpurge time. Setting this parameter to zero
disables postpurge.
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