Variable Air Volume (Vav) Unit Fan Operation (Modulating Gas Heat Only); Ignition Control Module; High Temperature Limit Operation And Loca; Tion - Trane Voyager CV Installation And Maintenance Manual

Sequence of Operation
Variable Air Volume (VAV) Unit Fan
Operation (Modulating Gas Heat Only)
During Changeover Heat (LTB5-1 shorted to LTB5-2), the
unit will heat to the Supply Air Heating Setpoint +/- 7ºF . The
VFD will modulate to maintain the Static Pressure
Setpoint.

Ignition Control Module

There is a green LED located on the ignition module. Any
time the Ignition module is powered, the LED will be on to
provide status of the ignition system.
• Steady OFF - no power/ internal failure
• Steady ON - no diagnostic, no call for heat
• Slow flash rate ¾ second on, ¼ second off - normal call
for heat
Error Code Flashes
• One flash - Communication loss between RTRM and
IGN
• Two flashes - System lockout; failed to detect or sustain
flame (3 tries, lockout after 3
• Three flashes - Not used
• Four flashes - High limit switch TCO1, TCO2, or TCO3
open (auto reset)
• Five flashes - Flame sensed and gas valve not
energized; or flame sensed and no call for heat (auto
reset)
The pause between groups of flashes is approximately
two seconds.
High Temperature Limit Operation and
Location
All of the heater limit controls are automatic reset. The
high limit cutouts (TCO1) and/or (TCO3) protect against
abnormally high supply air temperature. The fan failure
limit (TCO2) protects against abnormally high heat build
up due to excessive high limit (TCO1) (TCO3) cycling if the
indoor fan motor (IDM) fails. If TCO1, TCO2, or TCO3 open
during a heating call, the heat will shut down and the
supply fan will be forced to run. The heat will automatically
restart should the TCO circuit re-close during an active
heating call. While the TCO circuit is open, a heat fail
diagnostic will be sent from the IGN to the RTRM.
The TCO1 and TCO3 is located in the bottom right corner
of the burner assemblies on both downflow and horizontal
units. TCO2 is located on the IDM partition panel; below
and to the right of the blower housing on downflow units.
On horizontal units, TCO2 is located on the IDM partition
panel above the blower housing.
92
rd
try)
Electric Heat Sequence Of
Operation
Constant Volume (CV)
When heat is required and the Fan selection switch is in the
"AUTO" position for constant volume applications, the
RTRM energizes the Supply Fan approximately one
second before energizing the first stage electric heat
contactor (AH). A 10 seconds minimum "off" time delay
must elapse before the first stage heater is activated.
When the heating cycle is completed, the RTRM de-
energizes the Fan and the heater contactor (AH) at the
same time.
The RTRM cycles the first stage of heat as required to
maintain zone temperature. If the first stage cannot satisfy
the heating requirement, the RTRM energizes the second
stage electric heat contactors (BH) and (CH) providing first
stage has been on for at least 10 seconds or the second
stage has been off for at least 10 seconds. (CH contactor is
used on 54KW and larger heaters.)
The RTRM cycles the second stage electric heat as
required to maintain the zone temperature.

Variable Air Volume (VAV)

During Unoccupied heating, Morning Warm up, or
Daytime Warm up, the VHR relay will be energized for at
least 6 minutes and the VFD output will go to 100%. The
heaters will stage on and off to satisfy the zone
temperature setpoint.
Variable Air Volume Applications
(Single Zone VAV) Sequence of
Operation
Occupied Cooling Operation
For normal Cooling operation, available Cooling capacity
will be staged or modulated in order to meet the calculated
discharge air setpoint between the user selected upper
and lower limits. If the current active cooling capacity is
controlling the discharge air within the deadband no
additional Cooling capacity change will be requested. As
the Discharge Air Temperature rises above the deadband
the control will request additional capacity as required
(additional compressor operation or economizer). As the
Discharge Air Temperature falls below the deadband the
algorithm will request a reduction in active capacity.
Economizer Cooling
During normal Economizer Cooling, the fan speed will
operate at its minimum. However, if the economizer is able
to meet the demand alone, due to desirable ambient
conditions, the supply fan speed will be allowed to
increase above the minimum prior to utilizing mechanical
cooling. Note that Economizer Enable/Disable decisions
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