Single Zone Variable Air Volume (Vav) Units - Trane IntelliPak SAHL Series Installation, Operation And Maintenance Manual

General Information
Supply Duct Static Pressure Control (Occupied)
The RTM relies on input from the duct pressure transducer when a unit is equipped with or a
Variable Frequency Drive to position to set the supply fan speed to maintain the supply duct static
pressure to within the static pressure setpoint deadband. See
Figure 3. Transducer Voltage Output vs. Pressure Input

Single Zone Variable Air Volume (VAV) Units

Occupied Heating - Supply Air Temperature
When a Discharge Temperature Control unit is equipped with "Modulating Heat" , and the system
is in an occupied mode, and the field supplied changeover relay contacts (5K87) have closed, the
supply air temperature will be controlled to the customer specified supply air heating setpoint. It
will remain in the heating status until the changeover relay contacts are opened.
Occupied Cooling - Supply Air Temperature
When a Discharge Temperature Control unit is in the occupied mode, the supply air temperature
will be controlled to the customers specified supply air cooling setpoint by modulating the
economizer and/or staging the mechanical cooling "On and Off" as required. The changeover relay
contacts must be open on units with "Modulating Heat" for the cooling to operate.
Daytime Warm-up
On Discharge Temperature Control units equipped with heat, if the zone temperature falls below
the daytime warm-up initiate temperature during the occupied mode, the system will switch to full
airflow. During this mode, the VAV box/unocc relay, RTM K3, will be energized (this is to signal the
VAV boxes to go to 100%). After the VAV box max stroke time has elapsed (factory set at 6 minutes),
the VFD/IGV output will be set to 100%. The airflow will be at 100% and the heat will be turned on
to control to the occupied heating setpoint. When the zone temperature reaches the daytime
warmup termination setpoint, the heat will be turned off, the K3 relay will be de-energized,
releasing the VAV boxes, the VFD/IGV output will go back to duct static pressure control and the
unit will return to discharge air control. If the occ zone heating setpoint is less than the DWU
26
-0.75 to 9.0 Iwc Pressure Transducer Voltage Output vs. Pressure Input
4.50
4.00
3.50
3.00
2.50
2.00
1.50
1.00
0.50
0.00
Figure 3
Pressure (inches w.c.)
below.
RT-SVX36G-EN