37 750-265
Interlock open response Lockout, Recycle
During prepurge after a delay to establish airflow, and during Ignition, MFEP, and Run, the
burner control requires the ILK to remain on. If it opens during Ignition, MFEP, or Run then
this parameter determines the response: either a lockout or a recycle back to the Safe Start
check.
If recycle is selected and ILK is open during prepurge: the purge timer is set to zero and the
prepurge state holds at time zero, waiting for the ILK to reclose which will resume purge
timing. If this hold persists for 30 seconds then the control will go to a Standby Delay
condition for 5 minutes, then try again.
These responses apply to both the ILK input and the IAS input (unless the Interrupted Air
Switch Enable parameter is set to “Disable”). If the burner control is in a hold condition (but
not a Standby Delay) waiting for ILK to turn on, then the burner control will indicate that it is
waiting for ILK so that the Annunciator can provide a corresponding value in the Annunciator
Hold parameter, for use by a display.
Interrupted air switch (IAS)
enable
Disable, Purge Only, Purge & Ignition
This parameter determines when the IAS input is tested. If set to “Disable” then the IAS input
is ignored by the burner control, and is used by the Annunciator. If set to “Purge Only” then
IAS is monitored in the same way as the ILK input, with the same responses, during the
Prepurge state. If set to “Purge & Ignition” then IAS is monitored in the same way as the ILK
input, with the same responses, during the Prepurge and Ignition states.
Prepurge time MM:SS
This parameter sets the burner control’s prepurge time. Setting this parameter to zero
disables prepurge.
Purge rate proving None, High Fire Switch, Fan Speed
This parameter determines the input used to confirm the purge rate has been reached. It is
unused and ignored if the Prepurge time is set to zero.
If set to None, the purge rate is commanded during prepurge but purge timing begins
immediately without waiting for any feedback.
If set to High Fire Switch then the HFS input must be on to prove the purge rate. Additionally,
if this is selected and HFS is already on upon exit from Standby then an additional 30 second
prepurge delay (indicating HFS jumpered) is enforced before the measured Prepurge time
begins. If the HFS opens during purge, the burner control will react as specified by the
equipment setup (typically by restarting or holding Prepurge).
If set to Fan Speed then the measured fan speed must be within the specified prepurge rate,
+/- 3% for 3 seconds before the rate is proven and the measured prepurge time begins. If the
fan speed later goes outside of the prepurge rate +/- 3% during purge, the burner control will
react as specified by the equipment setup (typically by restarting or holding Prepurge).
Lightoff rate proving None, Low Fire Switch, Fan Speed
This parameter determines the input used to confirm the rate has been reached for lighting
the burner.
If set to None, the lightoff rate is commanded during ignition but is not checked.
If set to Low Fire Switch then the LFS input must be on to prove the lightoff rate. Additionally,
if this is selected and LFS is already on upon exit from prepurge then an additional 30 second
delay (indicating LFS jumpered) is enforced before the Ignition time begins. If the LFS opens
during ignition, the burner control will react as specified by the equipment setup (typically by
locking out).
If set to Fan Speed then the measured fan speed must be within the specified lightoff rate, +/
- 3% for 3 seconds before the rate is proven and Ignition begins. If the fan speed later goes
outside of the prepurge rate +/- 3% during ignition or MFEP, the burner control will react as
specified by the equipment setup (typically by locking out).
Pre-ignition time Seconds
During the preignition time the igniter output is energized and the occurrence of flame is a
fault condition.
The purpose of this time is to prove that spark does not simulate flame. It may be set to zero
if no pre-ignition time is wanted.
Pilot type Interrupted, Intermittent, DBI
An interrupted pilot turns off at the end of the main flame establishing period (MFEP),
whereas an intermittent pilot remains on during the run period and thus there is no MFEP.
The third choice, DBI (direct burner ignition) indicates that there is no pilot and that the main
flame is lit directly using the igniter. The ignition time is fixed at 4 seconds whenever direct
burner ignition is selected.
Table 19. Burner Control Safety Parameters. (Continued)
Parameter Comment
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