Page 11
XC21 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 .
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 13.
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 6 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 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 14).
Field refrigerant piping consists of liquid and vapor lines
from the outdoor unit to the indoor unit coil (braze
connections).
Table 2. Refrigerant Connections and Line Set
Requirements
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 XC21 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, CORP. 9351−L9, 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 (XC21) 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.
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.
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.
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