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General Refrigerant Piping System Information
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Refrigerant Safety Standards
ASHRAE Standards 15-2010 and 34-2010 address refrigerant safety and the maximum allowable concentration of refrigerant in an occupied
space. Refrigerant will dissipate into the atmosphere, but a certain volume of air is required to safely dissipate the refrigerant. For R410A
refrigerant, the maximum allowable concentration of refrigerant is 26 lbs./1,000 cubic feet (Addendum L modified the RCL to 26) of occupied
spaces. Buildings with 24-hour occupancy are allowed half of that concentration.
If a single zone system develops a refrigerant leak, the entire refrigerant charge of the system will dump into the area where the leak occurs.
To meet ASHRAE Standards 15 and 34, the smallest room volume on the system must be calculated and compared to the maximum allow-
able concentration. Also consult state and local codes in regards to refrigerant safety.
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DEVICE CONNECTION LIMITATIONS
Device Connection Limitations
A single-zone system consists of one outdoor unit and one indoor
unit. One of the most critical elements of a single-zone system is
the refrigerant piping. If the connection piping is not within allowable
limits, there will be reliability, performance, noise, and vibration
issues. The table below lists pipe length limits that must be followed
in the design of a Single Zone Mega or Mega 115V refrigerant pipe
system. Refer to the figure at right for maximum length and elevation
of piping.
Table 9: Single Zone Mega and Mega 115V Refrigerant Piping System Limitations.
Figure 30: Single Zone Mega and Mega 115V System Layout.
Max Length = A
Max Elevation = B
Unit = Feet
Outdoor unit
Indoor unit
A
B
Outdoor unit
Indoor unit
A
B
Model Numbers LS090HEV2, LS120HEV2 LS180HEV2, LS240HEV2 LS090HXV2, LS120HXV2
Pipe Sizes
Vapor 3/8 inches 1/2 inches 3/8 inches
Liquid 1/4 inches 1/4 inches 1/4 inches
Pipe Length
(ELF = Equivalent Length
of pipe in Feet)
Standard Piping Length 24.6 24.6 24.6
Piping Length with No
Additional Refrigerant
24.6 24.6 24.6
Longest total equivalent
piping length
49.2 65.6 49.2
Shortest total equivalent
piping length
9.8 9.8 9.8
Distance between fittings
and indoor units or
outdoor units
LQFKHV LQFKHV LQFKHV
Elevation
(All Elevation Limitations
are Measured in Actual
Feet)
If outdoor unit is above
indoor unit
23 feet 32.8 feet 23 feet
If outdoor unit is below
indoor unit
23 feet 32.8 feet 23 feet
Additional Refrigerant Needed (oz/ft) 0.22 0.26 0.22
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