Page 11
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 − Cut ends of the refrigerant lines square (free from nicks
or dents). Debur the ends. The pipe must remain
round, do not pinch end of the line.
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) which are rated for use with R410A refrigerant.
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 pro-
tect them during brazing. Braze the line set to the ser-
vice valve.
4 − Wrap a wet cloth around the valve body and copper
tube stub to protect it from heat damage during braz-
ing. Wrap another wet cloth underneath the valve body
to protect the base paint.
NOTE − The tube end must stay bottomed in the fitting
during final assembly to ensure proper seating, sealing
and rigidity.
5 − Install the field−provided thermal expansion valve (ap-
proved for use with R410A refrigerant) in the liquid line
at the indoor coil.
Refrigerant Metering Device
HSXA19 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 11 for installation of the check expansion valve.
Metering Device Installation
expansion
valve
o−ring
o−ring
strainer
liquid line
stub
distributor
Figure 11
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.
NOTE − If the indoor unit line and set is new, skip this sec-
tion and go on to the Manifold Gauge Set section.
IMPORTANT
If this unit is being matched with an approved line
set or indoor coil which was previously charged
with HCFC−22 refrigerant, 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 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.
IMPORTANT
The Environmental Protection Agency prohibits the
intentional venting of HFC refrigerants during main-
tenance, service, repair and disposal of appliance.
Approved methods of recovery, recycling or reclaim-
ing must be followed.
