Download Print this page

Fujitsu FO20R Series Installation Instructions Manual page 13

Variable speed r-410a heat pump outdoor units
Hide thumbs

Advertisement

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
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 outdoor
unit and indoor coil
• Kinked liquid line
The total pressure drop allowed for the liquid line is 50
PSI [345 kPa]. The procedure for selecting the proper
liquid line is as follows:
• Measure the total amount of vertical separation
between the outdoor unit and indoor coil.
• Measure the total indoor length of liquid line re-
quired.
4.4.5 Vapor Line Selection
The purpose of the vapor line is to return superheat-
ed 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 important role in
returning oil to the compressor to prevent potential
damage to the bearings, valves, and scroll sets.
Also, an improperly sized vapor line can dramatical-
ly reduce capacity and performance of the system.
The procedure for selecting the proper vapor line is
as follows:
4.0 INSTALLATION
• Add all of the equivalent lengths associated with
length. This will equal your total equivalent line
length.
• Reference Table 2 to verify the calculated equiva-
lent 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 indoor unit, requires a 75' of 1/2" diameter
liquid line, 3/4" vapor line, 4 90° LR elbows, and a
• Fitting Equivalent Length (ft.) = (4 x .9') + 6' = 84.6'
• Total Equivalent Length (ft.) = 75' + 9.6' = 84.6'
This application is acceptable because the 25' vertical
rise is less than the maximum rise of 50' for this ap-
plication.
• Determine the total linear length of vapor line
required.
• Add all of the equivalent lengths associated with
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.
13

Advertisement

loading

  Related Manuals for Fujitsu FO20R Series

This manual is also suitable for:

Fo2420rvjcabFo3620rvjcabFo4820rvjcabFo6020rvjcab