Lennox CBX25UHV Series Installation And Service Procedure page 23

IMPORTANT
To prevent the build-up of high levels of nitrogen when
purging, be sure it is done in a well ventilated area. Purge
low pressure nitrogen (1 to 2 psig) through the refrigerant
piping during brazing. This will help to prevent oxidation
and the introduction of moisture into a system.
NOTE - When installing refrigerant lines longer than 50 feet,
see the Lennox Refrigerant Piping Design and Fabrication
Guidelines, CORP. 9351-L9, or contact Lennox Technical
Support Product Applications for assistance. To obtain the
correct information from Lennox, be sure to communicate
the following information:
1. Route the suction and liquid lines from the fittings on the
indoor coil to the fittings on the outdoor unit. Run the
lines in a direct path, avoiding unnecessary turns and
bends.
2. Make sure that the suction line is insulated over the
entire exposed length and that neither suction nor liquid
lines are in direct contact with floors, walls, duct
system, floor joists, or other piping.
3. Connect the suction and liquid lines to the evaporator
coil. Take care to protect the cabinet and internal
components as detailed in figure 34.
4. To avoid damaging the rubber grommets in the cabinet
while brazing, slide the rubber grommets over the
refrigerant lines until they are away from the heat
source.
5. Remove the expansion valve sensing bulb from its
shipping location in the unit. Place it where it will be
protected from the heat during brazing.
6. Braze using an alloy of silver or copper and phosphorus
with a melting point above 1,100°F (593°C).
NOTE - Do not use soft solder.
7. Allow refrigerant pipes to cool to room temperature.
8. Re-install the expansion valve sensing bulb onto the
suction line outside of the cabinet. See figure 35.
NOTE - Make sure to route copper refrigerant tubing
away from sharp edges and make sure that it does not
touch other metal surfaces. This prevents damage
caused by vibration or metal-on-metal contact.
9. Insulate the sensing bulb once it is positioned outside
of the cabinet.
10. Reinstall the rubber grommets into the refrigerant
piping panel.
NOTE - Make sure expansion valve capillary tube is not
touching metal edges or copper tubing.
11. Make sure outdoor unit has been placed according to
the Installation Instructions and is connected to the
refrigerant lines.
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