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STEP 2 -- REFRIGERANT PIPING -- New or
Existing Line Set and Indoor Coil
F
lush existing line set per industry standards. For
more information concerning flushing procedures,
refer to the XC25 Installation and Service Procedures
available on DaveNet.
CAUTION -
DO NOT attempt to
flush and re-use existing line sets or indoor coil when
the system contains
contaminants (i.e., compressor
burn out).
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 installa
tion. Take care to empty all existing traps. Polyol es
ter (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 sys
tem performance and capacity.
Failure to properly flush the system per the XC25
Installation and Service Procedures 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.
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 Haz
ard. Failure to follow this warning could re
sult in damage, personal injury 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 explosion, 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 COM
PRESSOR.
IMPORTANT !
If unit is equipped with a crankcase heater, and outdoor
ambient temperature is below 60°F, unit should be ener
gized 24 hours before startup to prevent compressor
damage as a result of slugging.
The XC25 is a variable capacity cooling and heat pump
system utilizing variable speed compressor technology.
With the variable speed compressor and variable pumping
capacity, additional consideration must be given to refri
gerant piping sizing and application. The guidelines below
are to be used exclusively for the XC25 systems.
COOLING SYSTEM (HFC410A)
S
Total equivalent length equals 180 feet (piping and all
fittings included).
NOTE — Length is general guide. Lengths may be more or
less, depending on remaining system design factors.
S
Maximum linear (actual) length = 150 feet.
S
Maximum linear liquid lift = 60 feet.
NOTE —
Maximum lifts are dependent on total length,
number of elbows, etc
.
that contribute to total pressure
drop.
S
Maximum length vapor riser equals 60 feet.
S
Up to 50 Linear Feet
: Use rated line sizes listed in
table 1.
S
Between 51 150 Linear Feet
: Crankcase heater and
nonbleed port TXV factory installed. No additional
components required. Vertical vapor riser must be
sized to the vapor riser listed in the table 2 on systems
with line sets longer than 51 feet. Use tables 2 and 3
to determine the correct liquid and vapor line sizes.
S
Over 150 Linear Feet
: not recommended.
S
Additional oil is not required for systems with line
lengths up to 150 feet.
SUCTION TRAPS
For systems with the outdoor unit 5 60 feet above the in
door unit, one trap must be installed at the bottom of the
suction riser
.
