13
XC25
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 16.
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 referenced in table 2, use the procedure
outlined under
Flushing the System
on page 19.
If refrigerant lines are routed through a wall, 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 7 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 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 19).
IMPORTANT
Mineral oils are not compatible with HFC-410A.
If oil
must be added, it must be a Polyol ester oil.
Recommended POE oils are Mobil EAL ARCTIC 22 CC or
ICI EMKARATE
t
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.
IMPORTANT !
If this unit is being matched with an approved line set
or indoor unit coil that 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 system
performance and capacity.
Failure to properly flush the system per the XC25
Installation and Service Procedures will void the
warranty.
WARNING
Refrigerant can be harmful if it is inhaled.
Refrigerant must be used and recovered
responsibly.
Failure to follow this warning may result in personal
injury or death.
WARNING
Fire, Explosion and Personal Safety
Hazard. Failure to follow this warning
could result in damage, personal inju
ry or death.
Never use oxygen to pressurize or
purge refrigeration lines. Oxygen,
when exposed to a spark or open
flame, can cause fire and/or an ex
plosion, that could result in property
damage, personal injury or death.
WARNING
When using a high pressure gas such
as 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).
IMPORTANT !
Some scroll compressors have an internal vacuum
protector that will unload scrolls when suction pres
sure goes below 20 psig. A hissing sound will be
heard when the compressor is running unloaded.
Protector will reset when low pressure in system is
raised above 40 psig. DO NOT REPLACE COMPRES
SOR.
The XC25 is a variable-capacity cooling system utilizing
variable-speed compressor technology. With the variable-
speed compressor and variable pumping capacity,
additional consideration must be given to refrigerant piping
sizing and application. The following guidelines are to be
used exclusively for the XC25 systems.
