Schwank ATH Brooder/Agricultural Series - Manual (Page 19)

GP-MATH-BX-10A
ATH / IA Manual
RD: Nov, 2005
RL: 10
KH
Page 15
15. SEQUENCE OF OPERATION / FLAME RECOVERY/ SAFETY LOCKOUT
Start up - Heat Mode
When the thermostat is set above the ambient temperature, 120 VAC is supplied to the L1 ter-
minal. When this occurs the control will power up and perform a self-check routine and begin a
prepurge*, if selected. Following the pre-purge, the gas valve is energized and sparks com-
mence until flame is detected or the Trial For Ignition (TFI) period expires.
When flame is detected, the spark is shut off and the gas valve remains energized. The thermo-
stat and burner flame are constantly monitored to ensure that the system is functioning properly.
When the thermostat is satisfied and the demand for heat ends, the gas valve is de-energized im-
mediately and the flame is extinguished.
Flame Failure During TFI Period
Should the burner fail to light or flame is not detected during the first trial for ignition period,
the gas valve is de-energized and the control starts the inter-purge sequence before another igni-
tion attempt. After inter-purge, the control will attempt two additional ignition trials. If these
attempts are unsuccessful the control will go into lockout mode.
Flame Failure of Established Flame
Re -Ignition
If the established flame signal is lost while the burner is operating, the control responds and be-
gins sparking within 0.8 seconds. The spark will be energized for the duration of the trial-for-
ignition period in an attempt to re-light the burner. If flame is re-established, normal operation
resumes.
If the Burner does not light after the first attempt, the inter-purge sequence is completed be-
tween attempts to re-light the burner. If the burner fails to light after the third try, the control
will de-energize the gas valve and go into lockout mode. See Lockout Recovery
Lockout Mode (On-Board Safety System)
After single or multiple attempts to light the burner have failed or flame is not established, the
control automatically enters lockout The control will not open the gas valve unless there is in-
tervention by the user. See Lockout Recovery.
Lockout Recovery
For lockout recovery, reset the thermostat
below ambient temperature or remove the 120 VAC power supply for 5 seconds