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4 − Remove the pressure tap valve cores from the
HSXA12 unit’s service valves. Connect an R22 cylin-
der with clean refrigerant to the vapor service valve.
Connect the R22 gauge set to the liquid line valve and
connect a recovery machine with an empty recovery
tank to the gauge set.
5 − Set the recovery machine for liquid recovery and start
the recovery machine. Open the gauge set valves to
allow the recovery machine to pull a vacuum on the ex-
isting system line set and indoor coil.
6 − Invert the cylinder of clean R22 and open its valve to
allow liquid refrigerant to flow into the system through
the vapor line valve. Allow the refrigerant to pass from
the cylinder and through the line set and the indoor coil
before it enters the recovery machine.
7 − After all of the liquid refrigerant has been recovered,
switch the recovery machine to vapor recovery so that
all of the R22 vapor is recovered. Allow the recovery
machine to pull a vacuum on the system.
NOTE − A single system flush should remove all of the
mineral oil from the existing refrigerant lines and in-
door coil. A second flushing may be done (using clean
refrigerant) if insufficient amounts of mineral oil were
removed during the first flush.
Each time the system
is flushed, you must allow the recovery machine
to pull a vacuum on the system at the end of the
procedure.
8 − Close the valve on the inverted R22 drum and the
gauge set valves. Pump the remaining refrigerant out
of the recovery machine and turn the machine off.
9 − Use nitrogen to break the vacuum on the refrigerant
lines and indoor coil before removing the recovery ma-
chine, gauges and R22 refrigerant drum. Reinstall
pressure tap valve cores into HSXA12 service valves.
10 −Install the provided
fixed orifice
in the liquid line at the
indoor coil.
Refrigerant Metering Device
HSXA12 units are applicable to either fixed orifice or an
expansion valve system. See the indoor coil installation
instructions and the Lennox Engineering Handbook for
approved TXV and fixed orifice match−ups and application
information. Table 1 lists the unit liquid and vapor line sizes
and corresponding line sets.
Fixed Orifice Systems
HSXA12 units are shipped with a fixed orifice refrigerant
metering device. Replace the existing indoor unit fixed ori-
fice with the orifice supplied with the outdoor unit. Place the
supplied fixed orifice sticker on the indoor cabinet after
installation. See table 2 for the fixed orifice size for each
unit. In nonstandard applications, the provided fixed orifice
may not be appropriately sized.
Refer to the Engineering
Handbook for specific orifice information.
Table 2
Fixed Orifice Drill Sizes
Unit
Fixed Orifice Part #
Drill Size
HSXA12−018
29M88
.05
HSXA12−024
42J43
.063
HSXA12−030
42J43
.063
HSXA12−036
42J47
.071
HSXA12−042
42J51
.078
HSXA12−048
29M93
.081
HSXA12−060
42J57
.090
Install the fixed orifice as shown in figure 10. Do not twist
the cap tubes when loosening the seal nut from the orifice
housing. Use a wrench to back up the distributor.
Metering Device Installation
valve OR orifice
orifice
(factory−installed)
expansion
valve (opt.)
o−ring
o−ring
strainer
liquid line
stub
distributor
Figure 10
Expansion Valve Systems
Expansion valves equipped with Chatleff type fittings are
available from Lennox. Refer to the Engineering Handbook
for expansion valves for use with specific match−ups.
If you install an expansion valve with an indoor coil that
includes a fixed orifice, remove the orifice before the
expansion valve is installed.
IMPORTANT
Failure to remove a fixed orifice when installing an
expansion valve to the indoor coil will result in im-
proper operation and damage to the system.
Manifold Gauge Set
Manifold gauge sets used with systems charged with
R410A refrigerant must be capable of handling the higher
system operating pressures. The gauges should be rated
for use with pressures of 0 − 800 on the high side and a low
side of 30" vacuum to 250 psi with dampened speed to 500
psi. Gauge hoses must be rated for use at up to 800 psi of
pressure with a 4000 psi burst rating.
