| Options (cont.) 
Flexible Horizontal Discharge
The design of this option reduces discharge sound power level from typical
ducted systems which results in quieter system
operation. The option is factory mounted on the top
of the unit and has been engineered to optimize unit discharge performance by
eliminating duct turns or complex transitions. In
addition to improving the system sound levels, this also reduces system
installed cost.
Openings for attaching ductwork can be factory cut to customer requirements
helping to further reduce the system installed cost.
These discharge openings can be positioned for single or multiple discharge
from the front, rear, or either side. This allows
designers to position the unit within the equipment room to minimize floor space
requirements while maximizing system performance.
Refer to page 9 for more details on installation advantages.
Inlet Guide Vanes
Inlet guide vanes are among the most efficient and cost effective means of
providing airflow modulation in VAV systems. Trane
patented inlet guide vanes have proven reliability with thousands of installations
in Self-Contained units, Climate Changer® air handlers, and
VAV Rooftop units.
The inlet guide vanes are factory instaIled complete with electric actuator,
linkage, and static pressure controller. The duct
pressure sensing probe is shipped loose for field
installation. Field supplied 1/4 inch O.D. plastic tubing is to be installed between the probe and the unit mounted static
pressure controller.
The inlet guide vanes are controlled by the supply air static pressure controller,
which is part of the unit control module. The inlet
vanes will move to the closed position upon supply fan shutdown if unit power is on. Inlet vanes will be in the closed position
whenever the fan starts and will then modulate in
response to supply air static pressure. T
The static pressure controller offers field adjustment of the setpoint and control band by means of an adjustment knob on
the control panel.
Waterside Economizer
There are a number of alternatives available with this option:
- 4 Row — mechanically cleanable
- 4 Row — chemically cleanable
- 2 Row — mechanically cleanable
Each economizer is available with two control selections:
- Modulating Standard Control
- Modulating Energy Saving Control
All economizer control valves, piping between the economizer and the condenser,
and all wiring are factory installed. All piping and
control valves are located within the unit enclosure, and all water connections and controls are located on the left side of
the unit. Service access for cleaning is provided by
removing panels on the left side of the unit.
The waterside economizer will take advantage of cooling tower water to either precool the entering air to aid the
mechanical cooling process or, if the water temperature
is low enough, provide total system cooling.
MODULATING STANDARD CONTROL
— For economizer control, whenever the entering
water temperature is at least 5 degrees F below the return air temperature, the economizer function is enabled and water is
routed through the economizer first, and then through
the condenser. The economizer acts as the first stage of cooling. If the economizer
is unable to maintain the supply air setpoint, the unit
control module will bring on compressors as required to meet the setpoint.
When the economizer is acting as the first stage of cooling, and no compressor
is in operation, water flow is modulated through the
economizer in response to supply air temperature on VAV units and in response to
zone temperature on constant volume units. Since the
economizer valve and the bypass valve are proportional, full water flow through
the unit is always maintained. If the entering water
temperature is not at least 5 degrees F below the return air temperature, the economizer function is disabled, the
economizer valve closes and water is routed through the
condenser only.
Waterside economizer flow is controlled by two valves; one on the inlet to
the economizer and one which bypasses water around the
economizer. Whenever the supply fan is off, the bypass water valve is fully
open and the economizer valve is fully closed. Whenever
the unit is started, the valves are initially in this
position until the unit control module enables the economizer function. |
