Liquid Line Selection; Vapor Line Selection - Rheem ECONET RP2024BJVCA Installation Instructions Manual

4.4.4 Liquid Line Selection

The purpose of the liquid line is to transport warm
sub-cooled liquid refrigerant between the outdoor
unit to the indoor unit in the cooling mode. In the
heating mode, the liquid line returns sub-cooled
liquid from the indoor unit to the outdoor unit. It is
important not to allow the refrigerant to flash into
superheated vapor prior to entering the expansion
device of the indoor coil or outdoor unit. 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 separation between the out-
door unit and indoor coil
• Restricted liquid linear filter drier
• Kinked liquid line
The following Refrigerant Line Selection (Table 2)
lists the equivalent length per 25' [8 m] of liquid line
at various diameters up to 150' [46 m]. The total
pressure drop allowed for the liquid line is 50 PSI
Allowable
Unit Size Liquid Line
Size
5/16"
3/8"
3 Ton 5/16"
3/8"
1/2"
(Excerpt from Table 2A)

4.4.5 Vapor Line Selection

The purpose of the vapor line is to return super-
heated vapor to the condensing unit from the
indoor coil in the cooling mode. While in the heating
mode, the vapor line transports discharge vapor to
the indoor coil from the outdoor unit. Proper vapor
line sizing is important because it plays an impor-
tant role in returning oil to the compressor to pre-
vent potential damage to the bearings, valves, and
scroll sets. Also, an improperly sized vapor line can
dramatically reduce capacity and performance of
the system. The procedure for selecting the proper
vapor line is as follows:
Allowable
Vapor Line
< 25
Size
Maximum Vertical Separation / Capacity Multiplier
5/8" 25 / 0.99
5/8" 25 / 0.99
3/4 " 25 / 1.00
3/4 " 25 / 1.00
3/4 " 25 / 1.00
[345 kPa]. The procedure for selecting the proper
liquid line is as follows:
• Measure the total amount of vertical sepration
between the outdoor unit and indoor coil.
• Measure the total indoor length of liquid line
required.
• Add all of the equivalent lengths associated with
any fittings or accessories using Table 2.
• Add the linear length to the total fitting equiva-
lent length. This will equal your total equivalent
line length.
• Reference Table 2 to verify the calculated
equivalent length is acceptable with the required
vertical separation and diameter of liquid line.
Example: A 3-ton heat pump unit is installed 25'
below the ID unit, requires a 75' of 1/2" diameter
liquid line, and 4 90° LR elbows.
• Fitting Equivalent Length (ft.) = 4 × .9 = 3.6'
• Total Equivalent Length (ft.) = 75' + 3.6' = 78.6'
This application is acceptable because the 50'
vertical rise is less than the maximum rise of 75' for
this application.
Outdoor Unit ABOVE or BELOW Indoor Unit
Equivalent Length (Feet)
26-50 51-75 76-100
50 / 0.97 50 / 0.95 50 / 0.93
50 / 0.97 50 / 0.95 50 / 0.93
50 / 0.99 50 / 0.99 50 / 0.98
50 / 0.99 50 / 0.99 50 / 0.98
50 / 0.99 50 / 0.99 50 / 0.98
• Determine the total linear length of vapor line
required.
• Add all of the equivalent lengths associated with
any fittings or accessories using Table 1.
• Add the linear length and total fitting equivalent
length. This will equal your total equivalent line
length.
• Reference Table 2 to verify that the calculated
equivalent length falls within the compatibility
region of the chart.
• Verify capacity loss is acceptable for the applica-
tion.
4.0 INSTALLATION
101-125 126-150
36 / 0.91 NR
50 / 0.91 NR
36 / 0.97 20 / 0.96
50 / 0.97 50 / 0.96
50 / 0.97 50 / 0.96
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