Flushing Existing Line Set And Indoor Coil - Lennox 14HPX?018 Installation Instructions Manual

NOTE − The tube end must stay bottomed in the fitting
during final assembly to ensure proper seating, seal-
ing and rigidity.
5. Install a field−provided thermal expansion valve (ap-
proved for use with HFC−410A refrigerant) in the liquid
line at the indoor coil.
Flushing Existing Line Set and Indoor
Coil
WARNING
Danger of fire. Bleeding the refriger-
ant charge from only the high side
may result in the low side shell and
suction tubing being pressurized. Ap-
plication of a brazing torch while
pressurized may result in ignition of
the refrigerant and oil mixture − check
the high and low pressures before un-
brazing.
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 Janu-
ary 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 HFC−410A 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 in-
structions below will void the warranty.
CAUTION
This procedure should not be performed on sys-
tems which contain contaminants (Example: com-
pressor burn out).
REQUIRED EQUIPMENT
You will need the following equipment in order to flush the
existing line set and indoor coil: two clean HCFC−22 recov-
ery bottles, an oilless recovery machine with a pump down
feature, and two sets of gauges (one for use with HCFC−22
and one for use with the HFC−410A).
FLUSHING PROCEDURE
1. Remove existing HCFC−22 refrigerant using the ap-
propriate procedure below.
If the existing outdoor unit is not equipped with
shut−off valves, or if the unit is not operational
AND you plan to use the existing HCFC−22 refrig-
erant to flush the system −
D Disconnect all power to the existing outdoor unit.
505243 05/08
Connect to the existing unit, a clean recovery cyl-
D
inder and the recovery machine according to the
instructions provided with the recovery machine.
D Remove all HCFC−22 refrigerant from the existing
system. Check gauges after shutdown to confirm
that the entire system is completely void of refrig-
erant.
Disconnect the liquid and vapor lines from the ex-
D
isting outdoor unit.
If the existing outdoor unit is equipped with
manual shut−off valves AND you plan to use NEW
HCFC−22 refrigerant to flush the system −
Start the existing HCFC−22 system in the cooling
D
mode and close the liquid line valve.
Pump all of the existing HCFC−22 refrigerant back
D
into the outdoor unit. (It may be necessary to by-
pass the low pressure switches to ensure com-
plete refrigerant evacuation.)
When the low side system pressures reach 0 psig,
D
close the vapor line valve.
Disconnect all power to the existing outdoor unit.
D
Check gauges after shutdown to confirm that the
valves are not allowing refrigerant to flow back into
the low side of the system.
Disconnect the liquid and vapor lines from the ex-
D
isting outdoor unit.
2. Remove the existing outdoor unit. Set the new
HFC−410A unit and follow the brazing connection pro-
cedure (see page 7) to make line set connections.
DO NOT install metering device at this time.
3. Make low voltage and line voltage connections to the
new outdoor unit. DO NOT turn on power to the unit
or open outdoor unit service valves at this time.
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.
4. Remove the existing refrigerant flow control orifice or
thermal expansion/check valve before continuing with
flushing procedures. The existing devices are not ap-
proved for use with HFC−410A refrigerant and may
prevent proper flushing. Use a field−provided fitting to
reconnect the lines.
5. Remove the pressure tap valve cores from the 14HPX
unit's service valves. Connect an HCFC−22 cylinder
with clean refrigerant to the vapor service valve. Con-
nect the HCFC−22 gauge set to the liquid line valve and
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 HCFC−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.
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