Installation and Maintenance Manual

Installation - Mechanical
62 RLC-SVX09H-EN
System Configuration
The system can be configured in any of the primary
arrangements as shown in Figure 35, p. 59, Figure 36,
p. 59 and Figure 37, p. 60. The configuration and its
associated elevation, along with the total distance
between the RTUD and the air-cooled condenser, plays a
critical role in determining the liquid line and discharge
line sizes.This will also affect the field refrigerant and oil
charges. Consequently, there are physical limits which
must not be violated if the system is to operate as
designed. Please note the following restrictions:
1. The discharge line sizing is different for different
leaving evaporator water temperatures.
2. The total distance between the RTUD and the air-
cooled condenser must not exceed 200 actual feet or
300 equivalent feet.
3. When the air-cooled condenser is installed at the same
level or below the compressor-chiller, liquid line risers
must not be more than 15 ft above the base of the
condenser.
4. Discharge line risers cannot exceed an elevation
difference greater than 100 actual feet without a
minimum of 2% efficiency decrease.
5. See Figure 35, Figure 36 and Figure 37. for location of
recommended traps.
6. Circuit #1 on the condenser must be connected to
Circuit#1ontheRTUDunit.
Equivalent Line Length
To determine the appropriate size for field installed liquid
and discharge lines, it is first necessary to establish the
equivalent length of pipe for each line, including the added
flow resistance of elbows, valves, etc. An initial
approximation can be made by assuming that the
equivalent length of pipe is 1.5 times the actual pipe
length.
Note: Table 39, p. 62 states the equivalent length, in feet,
for various non-ferrous valves and fittings. When
calculating the equivalent length, do not include
piping of the unit. Only field piping must be
considered.
Liquid Line Sizing
Trane recommends that the liquid line diameter be as
small as possible, while maintaining acceptable pressure
drop.This is necessary to minimize refrigerant charge.The
total length between the components must not exceed 200
actual feet or 300 equivalent feet.
The liquid line risers must not exceed 15 feet from the base
of the air-cooled condenser.The liquid line does not have
to be pitched. Liquid line sizing for these units when
installed with aTrane Levitor II air-cooled condenser are
shown in Table 40, p. 63 through Table 51, p. 66. Line
sizing for other condensers must be done manually not to
violate the 5°F subcooling requirement at the EXV.
Liquid lines are not typically insulated. However, if the
lines run through an area of high ambient temperature (eg.
boiler room), subcooling may drop below required levels.
In these situations, insulate the liquid lines.
Use of a liquid line receiver is not recommended because
it adds to the overall refrigerant volume of the circuit.
Note: In case of power failure to the expansion valve, the
amount of liquid refrigerant contained in the
refrigerant system must not exceed the holding
capacity of the evaporator. See Table 64, p. 71 for
the maximum allowable charge in each circuit.
Note: Height in Table 40 through Table 51 is the raise in
elevation of the RTUD unit above the condensing
unit.
NOTICE:
Equipment Damage!
If circuits are crossed, serious equipment damage
may occur.
Table 39. Equivalent lengths of non-ferrous valves and
fittings
Line Size
OD (in)
Globe
Valve (ft)
Angle
Valve (ft)
Short
Radius
Elbow (ft)
Long
Radius
Elbow (ft)
1 1/8 87 29 2.7 1.9
1 3/8 102 33 3.2 2.2
1 5/8 115 34 3.8 2.6
2 1/8 141 39 5.2 3.4
2 5/8 159 44 6.5 4.2
3 1/8 185 53 8 5.1
3 5/8 216 66 10 6.3
4 1/8 248 76 12 7.3