Adding Refrigerant For Longer Line Set; Leak Test And Evacuation; Leak Test; Triple Evacuation Procedure - Lennox MCB Series Installation Instruction

Adding Refrigerant for Longer Line Set

For adding additional refrigerant for longer line sets, see "Table 5. Line Set Guide".
Be sure to add the proper amount of additional refrigerant. Failure to do so may result in reduced performance.
Line Set Diameters (in.)
System
Size (KBtu)
Liquid
009 1/4
012 1/4
018 1/4
024 3/8

Leak Test and Evacuation

Air and moisture remaining in the refrigerant system will
have undesirable effects as indicated below:
• Pressure in the system rises.
• Operating current rises.
• Cooling or heating efficiency drops.
• Moisture in the refrigerant circuit may freeze.
• Water may lead to corrosion of parts in the refrigera­
tion system.
The line set between the indoor and outdoor units
must be leak tested and evacuated to remove any non­
condensables and moisture from the system.

Leak Test

Use the following procedure to test for system leaks:
1. Connect the manifold gauge set and dry nitrogen gas
cylinder to the suction and gas service ports.
2. Open valve on nitrogen cylinder.
3. Pressurize the system per the pressure test
specifications in
Specifications".
4. Check that the system pressure remains stable. If
there is any movement check system for leaks.
5. After the system is found to be free of leaks:
• Close valve on nitrogen cylinder.
• Relieve the nitrogen pressure by: loosening the
charge hose connector at the nitrogen cylinder.
• When the system pressure is reduced to normal,
disconnect the hose from the cylinder.
Table 6. Pressure Test Specifications
Bar Psig kPa
1 3 44 303
2 15 220 1517
3 32 470 3241
4 45 650 4482
5 32 470 3241
Table 5. Line Set Guide
Each system size has a line set length and vertical elevation parameters.
Maximum Elevation
Outdoor Unit BELOW
Indoor Unit - Feet
Gas
(Meter)
3/8 82 (25)
1/2 82 (25)
1/2 98 (30)
5/8 98 (30)
"Table 6. Pressure
Duration
Minimum of 10 minutes
Minimum of 10 minutes
Minimum of 10 minutes
1 hour. Stress test to prove the
integrity of the complete installation.
24 hours. Lower system pressure
test, after confirmation No. 4 was
successfully completed.
Maximum
Elevation Maximum Line
Outdoor Unit
ABOVE Indoor Feet (Meters)
Unit - Feet (Meter)
33 (10)
33 (10)
66 (20)
66 (20)
IMPORTANT
Use only oxygen-free nitrogen (OFN).

Triple Evacuation Procedure

A Micron or Torr gauge must be used for this procedure.
1. Discharge the oxygen-free nitrogen and evacuate the
system to a reading of 8000 Microns (8 Torr) using all
service valves.
2. Break the vacuum by allowing nitrogen into the port
connections (liquid and gas line pipes) until a positive
pressure is achieved.
3. Evacuate the system to a reading of 5000 Microns (5
Torr).
4. Break the vacuum by allowing nitrogen into the port
connections (liquid and gas line pipes) until a positive
pressure is achieved.
5. Evacuate the system to a minimum reading of 500
Microns (0.5 Torr).
6. For a moisture­free system, ensure the vacuum is
held without movement for a minimum of 4 hours.
Test
7. If vacuum fails to hold, carry out steps 2 through 6
until vacuum holds.

Wiring Connections

In the U.S.A., wiring must conform with current local
codes and the current National Electric Code (NEC).
In Canada, wiring must conform with current local codes
and the current Canadian Electrical Code (CEC).
Electric Shock Hazard. Can cause injury or death. Unit
must be rounded in accordance with national and local
codes.
Line voltage is present at all components when unit is
not in operation. Disconnect all remote electric power
supplies before opening access panel. Unit may have
multiple power sources.
12
Additional Refrigerant for
Set Length - greater than 25 Foot Line Set
82 (25)
For the additional charging, we
82 (25)
recommend 0.161 oz. for 1/4"
liquid line and 0.322 oz. for 3/8"
98 (30)
liquid line per foot.
98 (30)
WARNING
Length