Humidifier Water Supply Line
Units supplied with the optional humidifier package have a 1/4 in. (6.4 mm) copper compression fitting
connection for water inlet. Supply pressure range is 10 psig to 150 psig. Required flow rate is 1gpm
(3.8lpm). A shut-off valve should be installed in this line to isolate the humidifier for maintenance.
NOTE: Do NOT route humidifier supply line in front of filter box access panel.
Chilled Water Piping—On chilled water units install manual service shut-off valves at the supply and
return lines of each unit. These shut-off valves are used for routine service or emergency isolation of the
unit.
Chilled water supply and return lines must be insulated. Insulating them will prevent condensation of the
water supply and return lines to the unit.
The minimum recommended water temperature is 42°F (5.5°C). Connection sizes are 1-1/8" (28.6mm) OD
copper.
Water/Glycol Piping—Water- and glycol-cooled systems require coolant loop connections as specified in
the condensing unit installation instructions.
Refrigerant R-407C Piping—All split systems require two refrigerant lines (an insulated copper suction
line and a copper liquid line) between the evaporator and the condensing unit.
WARNING! Risk of explosive discharge of high pressure refrigerant. Can cause serious injury.
Relieve refrigerant system pressure before working with piping/connections.
Two possible methods exist for installing the copper suction and liquid lines.
• Close coupling the units together using the quick connects. (See Figure 7.8 on page39).
• Using an optional sweat adapter kit and hard piping between the two units.
All refrigeration piping should be installed with high temperature brazed joints. Prevailing good
refrigeration practices should be employed for piping supports, leak testing, evacuation, dehydration and
charging of the refrigeration circuits. The refrigeration piping should be isolated from the building by the
use of vibration isolating supports. To prevent tube damage when sealing openings in walls and to reduce
vibration transmission, use a soft flexible material to pack around the tubes.
When installing remote condensing units above the evaporator, the suction gas line should be trapped at
the evaporator. This trap will retain refrigerant oil in the off cycle. When the unit starts, oil in the trap is
carried up the vertical riser and returns to the compressor.
Equivalent Pipe
Length, ft (m)
Liquid Suction
50 (15) 1/2" 1-1/8"
100 (30.5) 5/8" 1-1/8"
150 (45.7) 5/8" 1-3/8"
Suction line and liquid line sizing based on < 3 psi pressure drop in each and suction line refrigerant velocities >1000FPM (5.1m/s) for proper oil return.
Table 7.6 Recommended refrigerant line sizes
Vertiv | Liebert Mini-Mate2—5 ton User Manual| 31
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