Fitting Losses; Liquid Line Selection - Rheem FO13C Series Installation Instructions Manual

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 fl ash any superheated vapor prior
to the expansion device of the indoor coil. The
fl ashing 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, fi ttings, vertical separation, acces-
sories, and fi lter dryers. The table below references
diff erent 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 fi ttings or accessories using the table above.
• Add the total length and fi tting 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
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