Start up - Heat Mode
120 VAC is supplied to the L1 terminal either from a thermostat
or other control device. When this occurs, the control will power up
and perform a self-check routine, flash the diagnostic LED
for one second, then turn off and begin a pre-purge*, 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 thermostat 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 immediately and the flame
is extinguished.
System Response to Flame Failures
Fenwal controls are configured with several options for managing
loss of flame.
Failure during TFI Period
SINGLE TRIAL MODEL
Should the burner fail to light or flame is not detected
during the TFI period, the gas valve is de-energized and
the control will go into lockout mode.
MULTI TRIAL MODEL
Should the burner fail to light or flame is not detected
during the first TFI period, the gas valve is de-energized
and the control will attempt two additional ignition trials
with inter-purge. If these attempts are unsuccessful,
the control will go into lockout mode.
Failure of Established Flame -Two Options
There are two methods for re-starting the burner after loss
of established flame. The Re-ignition option is the default
configuration for re-establishing flame and does not need to
be specified when ordering. If the Recycle option is desired,
please specify this when ordering so that a special part
number is assigned to the control by Fenwal.
RE-IGNITION
If the established flame signal is lost, the control responds
and begins sparking within 0.8 seconds of loss of flame.
This is considered the first re-ignition attempt. The spark will
be energized for the duration of the TFI period in
an attempt to re-light the burner. If flame is re-established,
normal operation resumes.
SINGLE TRIAL MODEL
If the burner does not light after the first re-ignition
attempt, the control will de-energize the gas valve
and go into lockout mode.
MULTI TRIAL MODEL
If the burner does not light after the first re-ignition
attempt, the inter-purge sequence is completed between
the next two attempts to re-light the burner. If the burner
fails to light after the third attempt, the control will
de-energize the gas valve and go into lockout mode.
RECYCLE
If the established flame signal is lost, the control responds
by shutting off the gas valve within 0.8 seconds.
SINGLE TRIAL MODEL
The control will begin the ignition cycle with the
pre-purge cycle, if a pre-purge cycle is programmed
into the control. Controls without pre-purge immediately
commence sparking for one TFI period. If flame is
re-established, normal operation resumes. If the burner
fails to light after the first try, the control will de-energize
the gas valve and go into lockout mode.
MULTI TRIAL MODEL
The control will begin the ignition cycle with the
inter-purge sequence and attempt three tries for ignition
including inter-purges. If flame is re-established, normal
operation resumes. If the burner fails to light after the
third try, the control will de-energize the gas valve and
go into lockout mode.
NOTE: The Recycle feature option requires a special part
number that is determined by contacting Fenwal.
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
mode. The control will not open the gas valve unless there is inter-
vention by the user or one hour has passed depending on the
model chosen. See Lockout Recovery.
Lockout Recovery - Two Options
There are two options for recovering from lockout mode.
When selecting the control, please specify one of the following meth-
ods for lockout recovery.
1. Thermostat/ Power Off Reset- requires the user to reset the thermo-
stat below ambient temperature or remove the 120 VAC power supply
for 5 seconds. The control will start the ignition sequence and attempt
to light the burner again.
2. Automatic Reset - After one hour, if the thermostat is still calling for
heat, the control will automatically start the ignition sequence and
attempt to light the burner again.
SEQUENCE OF OPERATION / FLAME RECOVERY/ SAFETY LOCKOUT
* The pre-purge and inter-purge are delays to allow gas to dissipate from the
combustion chamber. This control is not equipped with a combustion blower
relay and therefore does not initiate a fan powered purge.
Page 2 Series 35-70, 120 VAC Direct Spark Ignition Control www.fenwalcontrols.com 1-800-FENWAL-1
