RTWB-SVN01B-E4
15
Installation Mechanical
Water pressure gauges and
thermometers
Install field-supplied thermometers
and pressure gauges (with
manifolds, whenever practical) as
shown in Figure 7. Locate pressure
gauges or taps in a straight run of
pipes -avoid placement near elbows-
. Be sure to install the gauges at the
same elevation on each shell if the
shell has opposite-end water
connections.
To read manifolded water-pressure
gauges, open one valve and close
the other (depending upon the
reading desired). This eliminates
errors resulting from differently
calibrated gauges installed at
unmatched elevations.
Water-pressure-relief valves
Install pressure-relief valves in both
evaporator and condenser systems.
Failure to do so could result in shell
damage.
Install water-pressure-relief valves in
one of the condenser and one of the
evaporator water box drain
connections or on the shell side of
any shutoff valve. Water vessels with
close-coupled shutoff valves have a
high potential for hydrostatic
pressure buildup with a water
temperature increase. Refer to the
applicable regulation for relief-valve
installation guidelines.
Flow sensing devices
Use field-provided flow switches or
differential pressure switches with
pump interlocks to sense system
water flow. Flow switch locations are
schematically shown in Figure 7.
To provide chiller protection, install
and wire flow switches in series with
the water pump interlocks, for both
chilled-water and condenser-water
circuits (refer to the installation
electrical section). Specific
connections and schematic wiring
diagrams are shipped with the unit.
Flow switches must stop or prevent
compressor operation if either
system water flow drops off
drastically. Follow the
manufacturer's recommendations
for selection and installation
procedures. General guidelines for
flow switch installation are outlined
below.
• Mount the flow switch upright,
with a minimum of 5 pipe
diameters of straight, horizontal
run on each side.
• Do not install close to elbows,
orifices, or valves.
Note:
The arrow on the switch must
point in the direction of the water
flow.
To prevent switch fluttering, remove
all air from the water system.
Note:
The Unit Control Module
provides a 6-second time delay on
the flow-switch input before shutting
down the unit on a loss-of-flow
diagnostic. Contact a qualified
service organization if machine
shutdowns persist.
Adjust the switch to open when
water flow falls below nominal.
Refer to the evaporator and
condenser data table for minimum
flow recommendations. Flow-switch
contacts are closed on proof of
water flow.
W
WA
AR
RN
NIIN
NG
G
Refrigerant pressure relief-
valve venting
To prevent injury due to inhalation
of R134a gas, do not discharge
refrigerant anywhere. If multiple
chillers are installed, each unit must
have separate venting for its relief
valves. Consult local regulations for
any special relief-line requirements.
All relief-valve venting is the
responsibility of the installing
contractor.
All RTWB units use evaporator,
compressor, and condenser
pressure-relief-valves that must be
vented to the outside of the
building. Relief-valve connection
sizes and location are shown in the
unit submittals. Refer to national
regulation for relief valve vent line
sizing information.
To prevent capacity reduction and
relief-valve damage, do not exceed
vent piping code specifications.
Note:
After being opened once, relief
valves tend to leak.
