LGRED Installation Manual

33
General Refrigerant Piping System Information
Due to our policy of continuous product innovation, some specifications may change without notification.
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MULTI
F
MAX
MULTI
F
WITH
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 allow half of that concentration.
If a VRF 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 allowable
concentration. If the concentration level is higher than allowed, the following are some design suggestions to eliminate the problem:
• Split dual-frame and triple-frame systems into single-frame systems that have lower refrigerant charges.
• Add transfer grilles in the ceiling or walls of the smaller rooms to increase the volume of the room.
• Remove the smallest space from the system and serve it with a smaller mini-split system.
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DEVICE CONNECTION LIMITATIONS
Device Connection Limitations
• The minimum number of connected and operating indoor units to Multi F / Multi F MAX with LGRED systems is two, taking into consider-
ation the minimum combination ratio.
• The maximum number of indoor units for each Multi F / Multi F MAX with LGRED heat pump system is:
LMU180HHV = 2 LMU240HHV = 3 LMU300HHV = 4 LMU361HHV = 5 LMU421HHV = 6 LMU480HHV = 8
One of the most critical elements of multi-zone systems is the refrigerant piping. See below and the following page for pipe length limits that
must be followed in the design of Multi F and Multi F MAX with LGRED refrigerant pipe systems:
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Table 11: Multi F with LGRED Outdoor Unit Refrigerant Piping System Limitations.
Outdoor Unit Model (Btu/h)
LMU180HHV /
18,000
LMU240HHV /
24,000
LMU300HHV /
30,000
Max. Total System Piping Length (ft.)
164
A+B
246.1
A+B+C
246.1
A+B+C+D
Min. Length for One Branch (ft.) 9.8 9.8 9.8
Max. Length for One Branch (ft.) 82 82 82
Max. Elevation Between Each Indoor Unit
and Outdoor Unit (h1)
49.2 49.2 49.2
Max. Elevation Between Indoor Units (h2) 24.6 24.6 24.6
Max. Combination of Indoor Units 24,000 33,000 40,000
h2
h1
A
B
Figure 22: Multi F Refrigerant Piping System
Limitations (LMU180HHV Example).
Multi F with LGRED Outdoor Unit Piping Length
and Elevation Limitations
Example of a Multi F with LGRED System
Example: LMU300HHV outdoor unit with four (4) indoor units
connected.
ODU: Outdoor Unit.
IDU: Indoor Unit.
A, B, C, D: Pipes from Outdoor Unit to Indoor Unit.
Max. 49.2 feet
Max. 24.6 feet
A
B
C
D