Page 11
XP21 SERIES
New or Replacement Line Set
REFRIGERANT LINE SET
This section provides information on installation or
replacement of existing line set. If new or replacement line
set is not being installed then proceed to
Brazing
Connections
on page 13.
IMPORTANT
Lennox highly recommends changing line set when
converting the existing system from HCFC−22 to
HFC−410A
.
If that is not possible and the line set is the
proper size as reference in table 2, use the procedure
outlined under
Flushing the System
on page 16.
If refrigerant lines are routed through a wall, then seal and
isolate the opening so vibration is not transmitted to the
building. Pay close attention to line set isolation during
installation of any HVAC system. When properly isolated
from building structures (walls, ceilings. floors), the
refrigerant lines will not create unnecessary vibration and
subsequent sounds. See figure 8 for recommended
installation practices. Also, consider the following when
placing and installing a high−efficiency outdoor unit.
IMPORTANT
Refrigerant lines must not contact structure.
Liquid lines that meter the refrigerant, such as RFC1 liquid
lines, must not be used in this application. Existing line set
of proper size as listed in table 2 may be reused. If system
was previously charged with HCFC−22 refrigerant, then
existing line set must be flushed (see
Flushing the System
on page 16).
Field refrigerant piping consists of liquid and vapor lines
from the outdoor unit to the indoor unit coil (braze
connections). Use Lennox L15 (sweat, non−flare) series
line set, or field−fabricated refrigerant line sizes as listed in
table 2.
Table 2. Refrigerant Line Set
Models
Liquid
Line
Vapor/
Suction
Line
L15 Line Set
−024, −036
and−048
3/8 (10)
7/8 (22)
L15 line set sizes are
dependent on unit match up.
See XP21 Engineering
Handbook to determine
correct line set sizes.
−060
3/8 (10)
1−1/8 (29)
Field Fabricated
NOTE Some applications may required a field−provided 7/8" to
1−1/8" adapter.
NOTE When installing refrigerant lines longer than 50
feet, see the Lennox Refrigerant Piping Design and
Fabrication Guidelines, or contact Lennox Technical
Support Product Applications for assistance.
To obtain the correct information from Lennox, be sure to
communicate the following information:
S
Model (XP21) and size of unit (e.g. −036).
S
Line set diameters for the unit being installed as listed
in table 2 and total length of installation.
S
Number of elbows vertical rise or drop in the piping.
The compressor is charged with sufficient Polyol Ester oil
(POE) for line set lengths up to 50 feet. Recommend
adding oil to system based on the amount of refrigerant
charge in the system. Systems with 20 pounds or less of
refrigerant required no oil to be added.
For systems over 20 pounds − add one ounce for every five
(5) pounds of HFC−410A refrigerant.
Recommended POE oils are Mobil EAL ARCTIC 22 CC or
ICI EMKARATE
t
RL32CF.
IMPORTANT
If this unit is being matched with an approved line set
or indoor unit coil which was previously charged with
mineral oil, or if it is being matched with a coil which
was manufactured before January of 1999, the coil
and line set must be flushed prior to installation. Take
care to empty all existing traps. Polyol ester (POE) oils
are used in Lennox units charged with HFC−410A
refrigerant. Residual mineral oil can act as an
insulator, preventing proper heat transfer. It can also
clog the expansion device, and reduce the system
performance and capacity.
Failure to properly flush the system per the
instructions below will void the warranty.
WARNING
Polyol Ester (POE) oils used with HFC−410A
refrigerant absorb moisture very quickly. It is very
important that the refrigerant system be kept closed
as much as possible. DO NOT remove line set caps
or service valve stub caps until you are ready to make
connections.
IMPORTANT
Mineral oils are not compatible with HFC−410A
.
If oil
must be added, it must be a Polyol Ester oil.
