Sealing The Unit - Lennox VRF VMDB Series Installation Instruction

• Field provided piping consists of two HVAC/R rated
copper lines connected to the indoor unit.
• Final equipment connections must be brazed
connections. Compression or other types of fittings
are not permitted for final connections.
• Refrigerant lines must be connected by a qualified
technician in accordance with established
procedures.
• Copper-phosphorous brazing alloys are to be used to
join all pipework connections where applicable.
• Always flow/purge nitrogen to avoid oxidation while
brazing.
• Always use an appropriate heat absorption compound
to protect the unit and internal sensors from conductive
heat while brazing.
Table 2. Refrigerant Piping Connections
Indoor Unit Size
Liquid Line
(Btuh)
7,000
9,000
12,000
15,000
18,000
24,000
30,000
36,000
48,000
1. The seal on the unit refrigerant piping connections
should remain in place until the last possible moment.
This will prevent dust or moisture from getting into the
refrigerant piping before it is connected.
2. Prior to brazing remove rubber air grommets from
indoor unit refrigerant line ports.
3. Slowly loosen one of the rubber plugs to release the
factory nitrogen charge. Remove the rubber plug from
both liquid and gas lines or cut pipework tails to suit
field installation conditions.
4. All refrigerant piping shall be free of defects, debris,
and oil.
5. Connect the liquid and gas lines to the evaporator coil.
6. Always use an appropriate heat absorption compound
to protect the unit and internal sensors from conductive
heat while brazing. Take care to protect the cabinet
and internal components.
7. Ensure nitrogen is flowing at all times during the
brazing process.
8. Braze connections. Allow pipe to cool before removing
wet rag.
9. Reinstall the rubber grommets into the refrigerant
piping panel.
10. Insulate both pipes individually.
Vapor Line
1/4" 1/2"
3/8" 5/8"
VMDB007-015
Use provided piping reducers.
Φ 1/4"
Φ 3/8"
Figure 15. VMDB007-015 Piping Reducers.

Sealing the Unit

Seal the unit so that warm air is not allowed into the
cabinet. Warm air introduces moisture, which results in
condensation problems.
This is especially important when the unit is installed in an
unconditioned area.
If installed in an unconditioned space, sealant should be
applied around the electrical wires, refrigerant tubing, and
condensate lines where they enter the cabinet.
There must be an air-tight seal between the unit and the
return air plenum. Use fiberglass sealing strips, caulking,
or equivalent sealing method between the plenum and
the air handler cabinet to ensure a tight seal. Return
air must not be drawn from a room where this unit or
any gas-fueled appliance (i.e. water heater) or carbon
monoxide-producing device (i.e. wood fireplace) is
installed.
11
Φ 3/4"
Φ 5/8"
WARNING