G—G861 Series Integrated Function Direct Spark Ignition Control Technical Bulletin 3
The following conditions occur in normal control operation:
•
Prepurge--Initial time delay between thermostat contact closure and
trial for ignition.
•
Trial-for-Ignition Time--Maximum time period that the main gas valve
and igniter energizes in an attempt to light the main burner.
•
Interpurge--Time period between trials for ignition when both the gas
valve and ignition source turn off and the inducer is on, allowing
unburned gas to escape before a succeeding trial can occur. (Retry takes
place only if proper ignition did not occur during the previous trial and
if total trials are less than three.)
•
Run--Main gas valve remains energized after a successful ignition trial.
•
Circulator/Blower “On Delay”--Fixed time delay after the flame is
sensed until the circulator/blower is energized.
•
Circulator/Blower “Off Delay”--Field selectable time delay after the
thermostat contacts open when the circulator/blower remains energized.
•
Postpurge--Time delay after the thermostat is satisfied when the
inducer remains energized.
Figure 2 illustrates the sequence of operation of the G861 control.
Upon receiving a call for heat from the system thermostat, the G861
follows this normal sequence of operation:
1.
Pressure Switch Detection--The control checks the inducer pressure
switch to ensure that it is open.
2.
Prepurge--The control energizes the inducer motor and verifies that the
pressure switch closes.
3.
Pressure Switch Detection--The control checks the pressure switch to
ensure that it remains closed during the prepurge period.
4.
Trial for Ignition--The control simultaneously energizes the spark
igniter and gas valve in an attempt to light the main burner. During the
trial time, the igniter is energized until flame is detected or until the
trial for ignition is complete, whichever occurs first.
5.
Run--If main burner flame is sensed up to the last 0.5 second of the
trial, the gas valve and inducer remain energized for the duration of the
heat call. The circulator/blower is energized after a 30-second blower
“on delay” time and remains energized for the duration of the heat call.
6.
Postpurge--Once the thermostat is satisfied, the gas valve is
de-energized and the inducer remains energized until the postpurge
period ends. The circulator/blower remains energized until the selected
blower “off delay” time has elapsed.
Operating
Mode
Definitions
Normal
Sequence of
Operation
Call for Heat