Trane CenTraVac Duplex CDHE, Operation & Maintenance Manual

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CDHF-SVU01C-EN
General
Information
Hot Water control
Occasionally CTV chillers are
selected to provide heating as a
primary mission. With hot water
temperature control, the chiller can
be used as a heating source or
cooling source. This feature provides
greater application flexibility. In this
case the operator selects a hot water
temperature and the chiller capacity
is modulated to maintain the hot
water setpoint. Heating is the primary
mission and cooling is a waste
product or is a secondary mission.
This type of operation requires an
endless source of evaporator load
(heat), such as well or lake water. The
chiller has only one condenser.
Note: Hot water temperature control
mode does not convert the chiller to
a heat pump. Heat pump refers to the
capability to change from a cooling-
driven application to a heating-driven
application by changing the
refrigerant path on the chiller. This is
impractical for centrifugal chillers as
it would be much easier to switch
over the water side.
This is NOT heat recovery. Although
this feature could be used to recover
heat in some form, there’s not a
second heat exchanger on the
condenser side.
The DynaView ™ Main Processor
provides the hot water temperature
control mode as standard. The
leaving condenser water temperature
is controlled to a hot water setpoint
between 80 and 140°F (26.7 to 60°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.
UCP provides a separate entry at the
DV to set the hot water setpoint.
Tracer 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 –J2-1 to J2-3 (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
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 hot water temperature control
feature is not designed to run with
HGBP, AFD, or ice making.
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.