40
MUL
TI V S System Installation Manual
Due to our policy of continuous product innovation, some specifications may change without notification.
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Leak Test
The indoor units must be OFF, and the DIP switches can be set to Vacuum Mode (see page 38) before initializing the leak test. The use of vacuum
mode is not required and may not always apply to pressure test procedure during initial equipment installation.
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with the service valves closed. Pressurize both the liquid and the vapor piping. If the pressure does not drop for twenty-four (24) hours, the
system passes the test and no leaks are present. If the pressure drops, there is a nitrogen leak in the system. Find the leak, repair, and then
test again.
Indoor Unit
Nitrogen Gas
Cylinder
Outdoor Unit
Liquide Piping
Vapor Piping
Liquid Side
Vapor Side
Close
Close
Figure 41: Leak Test Diagram.
• To avoid nitrogen entering the refrigerant system in a liquid state, the top of the cylinder must be higher than its bottom when the system
is pressurized.
• The cylinder should be used in a vertical standing position.
Leak Test Ambient Temperature Correction
If the ambient temperature changed between the time when pressure was applied and when the pressure drop was checked, adjust results
by factoring in approximately 1.5 psi for each 2°F of temperature difference.
Correction formula = (Ambient temperature when pressure was applied - Ambient temperature when pressure drop was checked) x 0.01.
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When pressure (550 psig) was applied, the ambient temperature was 80.6°F; 24 hours later when pressure drop (540 psi) was checked,
ambient temperature was 68°F.
Thus, 80.6 - 68 x 0.01 = 0.126. In this case, the pressure drop of 0.126 was due to temperature difference, therefore, there is no leak in the
refrigerant piping system.
Leak Test
REFRIGERANT PIPING CONNECTIONS
Use of combustible gases including com-
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Inert gas (nitrogen) should be used when
performing vacuum, checking leaks, cleaning
or repairs of pipes, etc.
WARNING
DANGER
Use of combustible gases including com-
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