Emerson Liebert MC Microchannel Outdoor Condenser 28 - 220kW User Manual

Indoor units and condensers both ship with holding charges of inert gas. Do not vent the condenser 

until all refrigerant piping is in place, ready for connection to indoor unit and condenser.

• Use copper piping with 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.

• Use a flow of dry nitrogen through the piping during brazing to prevent formation of copper oxide 

scale inside the piping. When copper is heated in the presence of air, copper oxide forms. 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

3

/min (0.5-1.5 l/s) inside the pipe during brazing is sufficient to 

displace the air. Control the flow using a suitable metering device.

• Ensure that the tubing surfaces to be brazed are clean and that the ends of the tubes have been 

carefully reamed to remove any burrs.

• Ensure that all loose material has been cleaned from inside the tubing before brazing.
• Protect all refrigerant line components within 18" (460mm) of the brazing site by wrapping them 

with wet cloth or suitable heat sink compound.

• Isolate piping from building using vibration isolating supports.
• Refer to the indoor unit’s user manual for appropriate piping sizes.
• Install traps on the hot gas (discharge) lines at the bottom of any rise over 5 feet high. If the rise 

exceeds 25 feet (7.5m), then install a trap in 20 foot (6m) increments or evenly divided.

• Pitch horizontal hot gas piping down at a minimum rate of 1/2" per 10 ft. (42mm per 10m) so that 

gravity will aid in moving oil in the direction of refrigerant/oil flow.

• Consult factory if Liebert Lee-Temp

™

 condenser is below the evaporator or if a condenser not 

equipped with Liebert Lee-Temp is more than 15 ft (4.6m) below the evaporator.

• Consult factory if piping run exceeds 150 feet (46m) equivalent length on traditional DX units.

Risk of explosive discharge from high-pressure refrigerant. Can cause equipment damage, 

injury or death.
Relieve pressure before working with or cutting into piping. 

Risk of refrigerant system rupture or explosion from overpressurization. Can cause 

equipment damage, injury or death.
Local building and plumbing codes may require that a fusible plug or other type of pressure 

relief device be installed in the system. Do not install a shutoff valve between the compressor 

and the field-installed relief device.
Consult local building and plumbing codes for installation requirements of additional 

pressure relief devices when isolation valves are installed as shown in Figure 18. Do not 

isolate any refrigerant circuits from overpressurization protection.