Rheem RA13 Series Installation Instructions Manual page 12

INSTALLATION
Interconnecting Tubing (cont�)
Interconnecting Tubing and
Fitting Losses
Refrigerant tubing is measured in terms of actual
length and equivalent length� Actual length is used
for refrigerant charge applications� Equivalent
length takes into account pressure losses from
90° Short
Line Size Radius
(in) Elbow
3/8
1/2
5/8
3/4
7/8
1-1/8
Liquid Line Selection
The purpose of the liquid line is to transport warm
sub-cooled liquid refrigerant from the outdoor unit
to the indoor unit� It is important not to allow the
refrigerant to flash any superheated vapor prior
to the expansion device of the indoor coil� The
flashing of refrigerant can occur for the following
reasons:
• Low refrigerant charge
• Improperly selected liquid line size
• Absorption of heat prior to expansion device
• Excessive vertical rise between the condenser
and evaporator
Table 2 lists the equivalent length per 25' of liquid
line at various diameters up to 300'� The total pres-
12
Equivalent Length for Fi ngs ( )
90° Long
Radius
Elbow
1.3 0.8
1.4 0.9
1.5 1
1.9 1.3
2.3 1.5
2.7 1.8
tubing length, fittings, vertical separation, acces-
sories, and filter dryers. The table below references
different commonly used equivalent lengths.
Table 1
45° Solenoid
Elbow Valve
0.3 6
0.4 9
0.5 12
0.6 14
0.7 15
0.9 22
sure drop allowed for the liquid line is 50 PSI� The
procedure for selecting the proper liquid line is as
follows:
• Measure the total amount of vertical rise
• Measure the total amount of liquid line needed
• Add all of the equivalent lengths associated with
any fittings or accessories using the table above.
• Add the total length and fitting pressure drop.
This will equal your total equivalent length�
• Round-down the total equivalent length to the
closest value in Table 2�
• Reference Table 2 to verify the round-down val-
ue of the calculated equivalent length is compat-
ible with the required vertical rise and diameter
of liquid line�
Note: Eleva on is defined as the
highest point of the line set to the
Figure 1
Check Site Filter
Valve Glass Dryer
4 0.4
5 0.6
6 0.8
7 0.9
8 1
12 1.5
lowest
6
6
6
6
6
6