Page 10
505095M 1/3/06
Flushing Connections
Low
Pressure
High
Pressure
Vapor Line
Service Valve
EXISTING
INDOOR COIL
XC15
UNIT
GAUGE MANIFOLD
Inverted R−22 Cylinder
(Contains clean R−22 to
be used for flushing)
Liquid Line
Service Valve
Inlet
Discharge
Tank Return
Closed
Opened
EXISTING LIQUID LINE
RECOVERY CYLINDER
NOTE − The inverted R−22 cylinder
must contain at least the same
amount of refrigerant as was recov-
ered from the existing system.
Figure 13
EXISTING VAPOR LINE
RECOVERY MACHINE
3. Make low voltage and line voltage connections to the
new outdoor unit.
Do NOT turn on power to unit or
open the outdoor unit service valves at this time.
4. Remove the existing refrigerant flow control orifice or
thermal expansion valve before continuing with flush-
ing procedures. Existing devices are not approved for
use with R−410A refrigerant and may prevent proper
flushing. Use a field−provided fitting to reconnect lines.
IMPORTANT
The line set and indoor coil must be flushed with
at least the same amount of clean refrigerant that
previously charged the system. Check the charge
in the flushing cylinder before proceeding.
5. Remove the pressure tap valve cores from the XC15
unit’s service valves. Connect an R−22 cylinder with
clean refrigerant to the vapor service valve. Connect
the R−22 gauge set to the liquid line valve. Connect a
recovery machine with an empty recovery tank to the
gauge set.
6. 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.
7. Invert the cylinder of clean R−22 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.
8. After all of the liquid refrigerant has been recovered,
switch the recovery machine to vapor recovery so that
all of the R−22 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.
9. Close the valve on the inverted R−22 drum and the
gauge set valves. Pump the remaining refrigerant out
of the recovery machine and turn the machine off.
10. Use dry nitrogen to break the vacuum on the refriger-
ant lines and indoor coil before removing the recovery
machine, gauges and R−22 refrigerant drum. Reinstall
pressure tap valve cores into XC15 service valves.
11. Install the expansion valve in the liquid line at the in-
door coil.
Refrigerant Metering Device
XC15 units may be used in thermal expansion valve (TXV)
systems only. See the indoor coil installation instructions
and the Lennox Engineering Handbook for approved TXV
match−ups and application information. Table 2 (on
Page 6) lists liquid and vapor line sizes and correspond-
ing line sets.
Expansion valves equipped with Chatleff type fittings are
available from Lennox. Refer to the Engineering Hand-
book for expansion valves for use with specific match−ups.
If you install an expansion valve with an indoor coil that in-
cludes a fixed orifice, remove the orifice before the expan-
sion valve is installed (see figure 14).
