Constant Volume (Cv) Units; Variable Air Volume (Vav) Units - Trane IntelliPak WEHE Series Installation, Operation And Maintenance Manual

General Information
a. drive the Hydronic Heat Actuator (4U15) to the full
open position.
b. turn the supply fan "Off".
c. closes the outside air damper;
d. turns "On" the SERVICE light at the Remote Panel.
e. initiates a "Freezestat" diagnostic to the Human
Interface.
High Duct Temp Thermostats (Optional 3S16
and 3S17)
Are binary input devices used on CV & VAV applications
with a Trane Communication Interface Module (TCI). They
provide "high limit" shutdown of the unit and requires a
manual reset. They are factory set to open if the supply air
temperature reaches 240°F, or the return air temperature
reaches 135°F. Once tripped, the thermostat can be reset by
pressing the button located on the sensor once the air
temperature has decreased approximately 25°F below the
cutout point.
Chilled Water Valve Control
The 0 to 10 VDC output from the heat module doubles as
the chilled water controller. The unit has isolating relays to
switch between heat and cool.

Constant Volume (CV) Units

Zone Temperature - Cooling
Relies on input from a sensor located directly in the space,
while a system is in the occupied "Cooling" mode. It
modulates the economizer (if equipped) and/or stages the
mechanical cooling "On and Off" as required to maintain
the zone temperature to within the cooling setpoint
deadband.
Zone Temperature - Heating
Relies on input from a sensor located directly in the space,
while a system is in the occupied "Heating" mode or an
unoccupied period, to stage the heat "on and off" or to
modulate the heating valve (hydronic heat only) as
required to maintain the zone temperature to within the
heating setpoint deadband. The supply fan will be
requested to operate any time there is a requested for heat.
On gas heat units, the fan will continue to run for 60
seconds after the furnace is turned off.
Supply Air Tempering
On CV units equipped with heat, if the supply air
temperature falls 10°F below the occupied heating
setpoint temperature while the heater is "Off", the first
stage of heat will be turned "On". The heater is turned "Off"
when the supply air temperature reaches 10°F above the
occupied heating setpoint temperature.
12

Variable Air Volume (VAV) Units

Occupied Heating - Supply Air Temperature
When a VAV units 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 VAV 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 VAV 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 the
unoccupied mode and stage the heat "On" to control to the
occupied heating setpoint. When the zone temperature
reaches the daytime warm-up termination setpoint, the
heat will be turned "Off" and the system will transition to
the occupied mode.
Unoccupied Heating - Zone Temperature
When a VAV unit is equipped with Gas, Electric, or
hydronic heat and is in an unoccupied mode, the zone
temperature will be controlled to within the customers
specified setpoint deadband.
Supply Air Tempering
On VAV units equipped with "Modulating Heat", if the
supply air temperature falls 10°F below the supply air
temperature setpoint, the hydronic heat valve will
modulate to maintain the supply air temperature to within
the low end of the setpoint deadband.
Supply Duct Static Pressure Control
(Occupied)
The RTM relies on input from the duct pressure transducer
when a unit is equipped with a Variable Frequency Drive to
position the supply fan speed to maintain the supply duct
static pressure to within the static pressure setpoint
deadband. Refer to the Transducer Voltage Output vs
Pressure Input values listed in the Space Pressure
Transducer (3U62) section,
Single Zone Variable Air Volume (SZVAV) Only
The IntelliPak controls platform will support Single Zone
VAV as an optional unit control type in order to meet
ASHRAE 90.1. The basic control will be a hybrid VAV/CV
configured unit that provides discharge temperature
control to a varying discharge air temperature target
(p. 11.)
RT-SVX35H-EN