Page 74
XP21
New or Replacement Line Set
REFRIGERANT LINE SET
This section provides information on installation or replace
ment of existing line set. If new or replacement line set is
not being installed then proceed to Brazing Connections on
page 76.
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 76.
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 refrig
erant lines will not create unnecessary vibration and
subsequent sounds. See figure 75 for recommended
installation practices. Also, consider the following when
placing and installing a high-efficiency outdoor unit.
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 23 may be reused. If system
was previously charged with HCFC-22 refrigerant, then ex
isting line set must be flushed (see Flushing the System on
page 76).
Field refrigerant piping consists of liquid and vapor lines
from the outdoor unit to the indoor unit coil (braze connec
tions). Use Lennox L15 (sweat, non-flare) series line set, or
field-fabricated refrigerant line sizes as listed in table 23.
Table 23. 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 Product
Specification bulletin 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 Fab
rication Guidelines, or contact Lennox Technical Support
Product Applications for assistance. To obtain the correct
information from Lennox, be sure to communicate the fol
lowing points:
Model (XP21) and size of unit (e.g. -036).
Line set diameters for the unit being installed as listed
in table 23 and total length of installation.
Number of elbows vertical rise or drop in the piping.
IMPORTANT
Mineral oils are not compatible with HFC-410A. If oil must
be added, it must be a Polyol ester oil.
The compressor is charged with sufficient Polyol ester oil
for line set lengths up to 50 feet. Recommend adding oil to
system based on the amount of refrigerant charge in the
system. No need to add oil in system with 20 pounds of re
frigerant or less. For systems over 20 pounds - add one
ounce of every five pounds of refrigerant.
Recommended topping-off POE oils are Mobil EAL ARC
TIC 22 CC or ICI EMKARATE RL32CF.
WARNING
Danger of fire. Bleeding the refrigerant
charge from only the high side may result
in the low side shell and suction tubing
being pressurized. Application of a
brazing torch while pressurized may
result in ignition of the refrigerant and oil
mixture - check the high and low
pressures before unbrazing.
WARNING
When using a high pressure gas such as
dry nitrogen to pressurize a refrigeration
or air conditioning system, use a regulator
that can control the pressure down to 1 or
2 psig (6.9 to 13.8 kPa).
CAUTION
Brazing alloys and flux contain materials which are
hazardous to your health.
Avoid breathing vapors or fumes from brazing
operations. Perform operations only in well ventilated
areas.
Wear gloves and protective goggles or face shield to
protect against burns.
Wash hands with soap and water after handling brazing
alloys and flux.
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