CVHE-SVX005B-EN
85
unit has a second heat exchanger on the condenser
side.
The Tracer® AdaptiView™ provides the Hot Water
Temperature Control mode as standard. The leaving
condenser water temperature is controlled to a hot
water setpoint between 80°F and 140°F (26.7°C and
60.0°C). The leaving evaporator water temperature is
left to drift to satisfy the heating load of the condenser.
In this application, the evaporator is normally piped
into a lake, well, or other source of constant
temperature water for the purpose of extracting heat.
In Hot Water Temperature Control mode, all the limit
modes and diagnostics operate as in normal cooling
with one exception: the leaving condenser water
temperature sensor is an MMR diagnostic when in Hot
Water Temperature Control mode. (It is an
informational warning in the Normal Cooling mode.)
In the Hot Water Temperature Control mode, the
differential-to-start and differential-to-stop setpoints
are used with respect to the hot water setpoint instead
of with the chilled water setpoint. The control panel
provides a separate entry at the Tracer® AdaptiView™
to set the hot water setpoint; Tracer® AdaptiView™ is
also able to set the hot water setpoint. In the Hot Water
mode, the external chilled water setpoint is the external
hot water setpoint; that is, a single analog input is
shared at the 1A16-J2-5 to 6 (ground).
An external binary input to select external Hot Water
Control mode is on the EXOP OPTIONAL module 1A18
terminals J2-3 to J2-4 (ground). Tracer® AdaptiView™
also has a binary input to select chilled water control or
hot water temperature control. There is no additional
leaving hot water temperature cutout; the HPC and
condenser limit provide for high temperature and
pressure protection.
In Hot Water Temperature Control, the softloading
pulldown rate limit operates as a softloading pullup
rate limit. The setpoint for setting the temperature rate
limit is the same setpoint for normal cooling as it is for
hot water temperature control.
The factory set PID tuning values for the leaving water
temperature control are the same settings for both
normal cooling and hot water temperature control.
Heat Recovery Cycle
Heat recovery is designed to salvage the heat that is
normally rejected to the atmosphere through the
cooling tower and put it to beneficial use. For example,
a high-rise office building may require simultaneous
heating and cooling during the winter months. With the
addition of a heat recovery cycle, heat removed from
the building cooling load can be transferred to areas of
the building that require heat.
NNoottee:: The heat recovery cycle is possible only if a
cooling load exists to act as a heat source.
To provide a heat recovery cycle, a heat-recovery
condenser is added to the unit. Though physically
identical to the standard cooling condenser, the heat-
recovery condenser is piped into a heat circuit rather
than to the cooling tower. During the heat recovery
cycle, the unit operates just as it does in the cooling
only mode except that the cooling load heat is rejected
to the heating water circuit rather than to the cooling
tower water circuit. When hot water is required, the
heating water circuit pumps energize. Water circulated
through the heat-recovery (or auxiliary) condenser tube
bundle by the pumps absorbs cooling load from the
compressed refrigerant gas discharged by the
compressor. The heated water is then used to satisfy
heating requirements.
An optional heat recovery water flow switch and heat
recovery water flow measurement is available.
Auxiliary Condensers
Unlike the heat-recovery condenser (which is designed
to satisfy comfort heating requirements), the auxiliary
condenser serves a preheat function only and is used in
those applications where hot water is needed for use in
kitchens, lavatories, etc. While the operation of the
auxiliary condenser is physically identical to that of the
heat-recovery condenser, it is comparatively smaller in
size and its heating capacity is not controlled. Trane
does not recommend operating the auxiliary
condenser alone because of its small size.
An optional aux condenser water flow switch and heat
recovery water flow measurement is available.
Control Panel Devices and Unit-
Mounted Devices
Unit Control Panel
Safety and operating controls are housed in the unit
control panel, the starter panel, and the purge control
panel. The control panel operator interface is called
Tracer® AdaptiView™ and is located on an adjustable
arm connected to the base of the control panel. For
more information about operating Tracer AdaptiView,
refer to Tracer AdaptiView Display for Water-cooled
CenTraVac Chillers with Symbio Operations Guide
(CTV-SVU004*-EN). For more information on the
Symbio™ 800 controller, refer to Symbio 800
Controller Installation, Operation, and Maintenance
(BAS-SVX080*-EN).
The control panel houses several other controls
modules called panel-mounted Low Level Intelligent
Devices (LLIDs), power supply, terminal block, fuse,
circuit breakers, and transformer. The inter-processor
communication (IPC) bus allows the communications
between LLIDs and the controller. Unit-mounted
devices are called frame-mounted LLIDs and can be
temperature sensors or pressure transducers. These
and other functional switches provide analog and
binary inputs to the control system.
SSttaarrtt--uupp aanndd SShhuutt--ddoowwnn
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