Direct Spark Ignition Control (Sequence Of Operation, 3-10 Ton Units Only); 1-Stage Units - Trane ReliaTel Diagnostic Manual

Direct Spark Ignition Control (Sequence of Operation, 3-
10 Ton Units Only)

1-stage units

Ignition control (IGN) runs a self check (including verification that the gas valve is de-energized).
IGN checks the high limit switch (TCO 1) for closed contacts, the pressure switch (PS) for open
contacts, flame rollout (FR) for closed contacts.
IGN energizes inducer blower. When PS closes, 20 second pre-purge begins. After 20 seconds, the
IGN energizes the spark and gas valve at the same time. The spark will stay energized for at least
2 seconds attempting to establish flame. If a flame is not established, the spark will continue up to
7 seconds. Once a flame is established, spark is de-energized and indoor blower motor (IBM) timing
begins. 45 seconds later, the RTRM energizes the IBM. When the zone sensor or thermostat is
satisfied, the gas valve is de-energized, the inducer runs for 5 seconds then stops (post-purge), and
the IBM runs for 60 seconds then stops unless being requested to run continuously.
2-stage units
Ignition control (IGN) runs a self check (including verification that the gas valve is de-energized).
IGN checks the high limit switches (TCO 1 & TCO 2) for closed contacts, the pressure switch (PS)
for open contacts, flame rollout (FR) for closed contacts.
IGN energizes inducer blower on high speed. When PS closes, 20 second (15 seconds on high, 5
seconds on low) pre-purge begins. After 20 seconds, the IGN energizes the spark and gas valve at
the same time. The spark will stay energized for at least 2 seconds attempting to establish flame.
If a flame is not established, the spark will continue up to 7 seconds. Once a flame is established,
spark is de-energized and indoor blower motor (IBM) timing begins. 45 seconds later, the RTRM
energizes the IBM. If deviation from setpoint is great enough, there is no minimum delay before
2
nd
energized, the inducer runs for 5 seconds then stops (post-purge), and the IBM runs for 60 seconds
then stops unless being requested to run continuously.
If the burner fails to ignite, the ignition module will attempt two more ignition cycles before locking
out. The green LED will indicate a lockout by two fast flashes. An ignition lockout can be reset by:
1. Opening for 3 seconds and closing the main power disconnect switch.
2. By switching the 'Mode' switch on the zone sensor to 'OFF' and then to the desired position, or
3. Allowing the ignition control module to reset automatically after one hour.
If the burner trips due to a high temperature limit, the unit will shut down and initiate a four flash
diagnostic. After the limit cools down and closes, the burner will again restart. There is no limit to
the number of high limit trips that can occur.
Figure 54. Direct Spark Ignition Control Sequence of Operation
1st Stage
call for heat
RT-SVD03G-EN
stage is energized. When the zone sensor or thermostat is satisfied, the gas valve is de-
Start trial
for ignition
7 sec trial for ignition
CBM 20 sec Pre-purge
2 sec minimum
1st stg on
2nd stg on
Minimum
Delay
Additional 5 sec
if needed
Start 45 second
delay for IDM
End call for heat
5 sec CBM
post-purge
CBM off
No
IDM off
IDM on for 60
or 90 sec
IDM on
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