Figure 12 Refrigerant Piping Diagram - Liebert Mini-Mate2 MMD24E User Manual

Field-Fabricated Piping
All field-fabricated refrigeration piping should use copper pipe with high-temperature brazed joints.
A brazing alloy with a minimum temperature of 1350°F (732°C), such as Sil-Fos. Avoid soft solders
such as 50/50 or 95/5.
1. Use sweat adapter kit matched to the Liebert Mini-Mate2 and outdoor condensing unit
refrigerant connection sizes.
2. Measure pipe runs and calculate pipe size and equivalent feet of suction and liquid lines per
Tables 8 and 12.
3. Use a flow of dry nitrogen through the piping during brazing to prevent formation of copper oxide
scale inside the piping. Copper oxide forms when copper is heated in the presence of air. POE oil
will dissolve these oxides from inside the copper pipes and deposit them throughout the system,
clogging filter driers and affecting other system components. A pure dry nitrogen flow of
1-3 ft /min (0.5-1.5 l/s) inside the pipe during brazing is sufficient to displace the air. Control the
3
flow using a suitable metering device.
4. Pressurize and leak-test the completed lines at approximately 150 psig (1034kPa) pressure.
5. Evacuate each line twice to 250 microns. Break the vacuum each time with clean, dry nitrogen.
6. Evacuate the lines a third time to 250 microns.
7. See Quick Connect Fittings on page 23 for the proper procedure to connect lines to each unit
of the split system.
8. Add refrigerant (R-407C) to the completed system as calculated per Table 10 for both liquid and
suction line sizes used.
When installing remote condensing units above the evaporator, the suction gas line should be trapped
at the evaporator. This trap will retain refrigerant oil during the Off cycle. When the unit starts, oil in
the trap is carried up the vertical riser and returns to the compressor (see Figure 12).

Figure 12 Refrigerant piping diagram

Evaporator
Suction Line Piping
Condensing Unit
Below Evaporator
Evaporator
NOTE
When installing remote condensing units below the evaporator, the suction gas line should be
trapped with an inverted trap the height of the evaporator. This prevents refrigerant migration
to the compressor during off cycles.
Pitch down 1/2" (13mm) per 10 ft. (3m)
NOTE
When installing remote condensing units below the
evaporator, the suction gas line should be trapped with
an inverted trap to the height of the evaporator . This
prevents refrigerant migration to the compressors
during off cycles . Maximum recommended vertical
level drop to condensing unit is 15 ft. (4.6m) .
Condensing
Unit
Condensing
Unit
Suction Line Piping
Condensing Unit Above Evaporator
Traps recommended at the base of riser exceeding
5 ft (1.5m) and every 20 feet (6m) of vertical rise.
Pitch down 1/2" (13mm) per 10 ft. (3m)
21
Site Preparation and Installation
See Table 9 for recommended maximum
vertical rise above/fall below evaporator.
® ™
Liebert Mini-Mate2