Supply Duct Static Pressure Control; Supply Air Temperature Reset; Vav Supply Air Tempering (Only Available With Modulating Gas Heat) - Trane Voyager CV Installation And Maintenance Manual

Startup
is switched from the "Heat" Mode or enters an
Unoccupied status.
Note: When a LCI is installed on a VAV unit, the MWU
setpoint located on the RTAM board is ignored. The
MWU and DWU setpoints come from the higher
priority LCI-R DAC.

Supply Duct Static Pressure Control

The supply duct static pressure is measured by a
transducer with a 0.25 to 2.125 Vdc proportional output
which corresponds to an adjustable supply duct static
pressure of 0.3" w.c. to 2.5" w.c. respectively with a
deadband adjustment range from 0.2" w.c. to 1.0" w.c. The
setpoint is adjustable on the RTAM Static Pressure
Setpoint potentiometer or through ICS.
Example:
Supply Duct Static setpoint = 2.0" w.c. (RTAM)
Deadband = 0.2" w.c. (RTAM)
Duct Static Control Range = 1.9" w.c. to 2.1" w.c.
Figure 43. Output vs. input
Transducer Voltage Output vs Pressure Input
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0.0
-0.5 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5
Pressure (inches w.c.)

Supply Air Temperature Reset

The supply air temperature can be reset by using one of
four DIP switch configurations on the RTAM or through ICS
when a valid supply air reset setpoint with a supply air
reset amount is given. A selectable reset amount of 0° F to
20°F via RTAM potentiometer or ICS is permissible for each
type of reset.
The amount of change applied to the supply air
temperature setpoint depends on how far the return air,
zone, or outdoor air temperature falls below the reset
temperature setpoint. If the return air, zone, or outdoor air
temperature is equal to or greater than the reset
temperature setpoint, the amount of change is zero.
If the return air, or zone temperature falls 3°F below the
reset temperature setpoint, the amount of reset applied to
the supply air temperature will equal the maximum
amount of reset selected.
If the outdoor air temperature falls 20°F below the reset
temperature setpoint, the amount of reset applied to the
48
supply air temperature will equal the maximum amount of
reset selected. The four DIP switch configurations are as
follows:
1. None - When RTAM DIP Switch #3 and #4 are in the
"Off" position, no reset will be allowed.
2. Reset based on Return Air Temperature - When RTAM
DIP Switch #3 is "Off" and Switch #4 is "On" , a
selectable supply air reset setpoint of 50°F to 90°F via
a unit mounted potentiometer or Tracer™ is
permissible.
3. Reset based on Zone Temperature - When RTAM DIP
Switch #3 is "On" and Switch #4 is "Off" , a selectable
supply air reset setpoint of 50°F to 90°F via RTAM
potentiometer or Tracer is permissible.
4. Reset based on Outdoor Air Temperature - When DIP
Switch #3 and #4 are "On" , a selectable supply air reset
setpoint of 0°F to 100°F via RTAM potentiometer or
Tracer is permissible.
VAV Supply Air Tempering (Only Available
with Modulating Gas Heat)
The gas heater will be modulated to prevent the Discharge
Air Temperature from falling below the Discharge
Temperature Deadband. Upon satisfying the Supply Air
Tempering requirements, a 5 minute SA Tempering Delay
timer will start whenever the modulating gas heat
combustion blower is commanded to 0 and must time out
before the unit will be allowed to re-enter "Cool" mode.
This timer will be reset to 5 minutes whenever there is an
active call for "Supply Air Tempering" . Tempering will be
discontinued whenever;
a. The 5 minutes "Supply Air Tempering Delay" timer
has timed-out and;
b. There is an active cooling request for VAV Occupied
Cooling.
RT-SVX34F-EN