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Isolation Grommets
Locate the provided isolation grommets. Use a knife to slit
the webbing on each grommet. Slide larger grommet onto
vapor line and smaller grommet onto liquid line. Insert
grommets into mullion to isolate refrigerant lines from
sheet metal edges.
WARNING
Polyol ester (POE) oils used with R410A 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 ser-
vice valve stub caps until you are ready to make
connections.
Brazing Connection Procedure
1 − The end of the refrigerant line must be cut square and
its internal shape must remain round. The line must be
free of nicks or dents and must be deburred (I.D. and
O.D.)
2 − Before making line set connections, use dry nitrogen to
purge the refrigerant piping. This will help to prevent
oxidation and the introduction of moisture into the sys-
tem.
3 − Use silver alloy brazing rods (5 or 6 percent minimum
silver alloy for copper−to−copper brazing or 45 percent
silver alloy for copper−to−brass or copper−to−steel braz-
ing). Wrap a wet cloth around the valve body and the
copper tube stub. Remove light maroon washers from
service valves and shield light maroon stickers in order
to protect them during brazing. Braze the line set to the
service valve.
4 − Quench the joint with water or a wet cloth to prevent
heat damage to the valve core and opening port.
IMPORTANT − The tube end must stay bottomed in the
fitting during final assembly to ensure proper seating,
sealing and rigidity.
Refrigerant Metering Device
HPXA15 units are used in check expansion valve systems
only. See the Lennox Engineering Handbook for approved
TXV match-ups and application information.
Check expansion valves equipped with Chatleff fittings
are available from Lennox. Refer to the Engineering
Handbook for applicable expansion valves for use with
specific match-ups.
If you install a check expansion valve with an indoor coil
that includes a fixed orifice, remove the orifice before
installing the check expansion valve.
See figure 1 for installation of the check expansion valve.
Metering Device Installation
expansion
valve
o−ring
o−ring
strainer
liquid line
stub
distributor
Figure 1
IMPORTANT
Failure to remove RFC orifice when installing an ex-
pansion valve on the indoor coil will result in improp-
er operation and damage to the system.
Flushing Existing Line Set & Indoor Coil
WARNING
Danger of fire. Bleeding the refrigerant
charge from only the high side may
result in the low side shell and suc-
tion tubing being pressurized. App-
plication of a brazing torch while pres-
surized may result in ignition of the
refrigerant and oil mixture − check the
high and low pressures before unbra-
zing.
IMPORTANT
If this unit is being matched with an approved line
set or indoor coil that was previously charged with
R22 refrigerant, or if it is being matched with a coil
that 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
R410A refrigerant. Residual mineral oil can act as an
insulator, preventing proper heat transfer. It can
also clog the thermal expansion valve, reducing
system performance and capacity.
Failure to properly flush the system per the instruc-
tions below will void the warranty.
CAUTION
This procedure should not be performed on sys-
tems which contain contaminants (Example: com-
pressor burn out).
