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Table 4.2 Summary of permitted refrigerant piping lengths and level differences
Total piping length
Equivalent length between the
farthest indoor unit and the
outdoor unit
Piping lengths
Piping between farthest indoor unit and first
indoor branch joint
Largest level difference
between indoor unit and
Level differences
outdoor unit
Largest level difference between indoor unit
The piping length and level difference requirements that
apply are summarized in Table 4.2 and are fully
described as follows.
1.
The piping between the farthest
Requirement 1:
indoor unit (N14) and the first outdoor branch joint
(M) should not exceed 150m (actual length) and
175m (equivalent length). (The equivalent length of
each branch joint is 0.5m, and the equivalent length
of each branch header is 1m.)
2.
The piping between the farthest
Requirement 2:
indoor unit (N14) and first indoor branch joint (A)
should not exceed 40m in length (Ʃ{L2 to L5} +e≤
40m or Ʃ{L6 to L10} + n≤40m) unless the following
conditions are met and the following measures are
taken, in which case the permitted length is up to
90m.
Conditions:
a)
Each indoor auxiliary pipe (from each indoor unit to
its nearest branch joint) joint does not exceed 40 m
in length (a to n each ≤ 40m).
b)
The difference in length between {the piping from
first indoor branch joint (A) to the farthest indoor unit
(N14)} and {the piping from the first indoor branch
joint (A) to the nearest indoor unit (N1) } does not
exceed 40m. That is: (Ʃ{L6 to L10} + n) - (L2 + a) ≤
40m.
Measures:
a)
Increase the diameter of the indoor gas pipes (the
piping between the first indoor branch joint and all
other indoor branch joints, L2 to L10) as follows,
except for indoor main pipes which are already the
same size as the main pipe (L1), for which no
diameter increases are required.
Table 4.3 Pipe size allowable increase diameters (mm)
Φ9.52 to Φ12.7
Φ12.7 to Φ15.9
Φ19.1 to Φ22.2
Φ22.2 to Φ25.4
Φ28.6 to Φ31.8
Φ31.8 to Φ38.1
Φ41.3 to Φ44.5
Φ44.5 to Φ50.8
Category
Actual length
Equivalent length
Outdoor unit is above
Outdoor unit is below
Φ15.9 to Φ19.1
Φ25.4 to Φ28.6
Φ38.1 to Φ41.3
Φ50.8 to Φ54.0
19
Permitted values
L1+L2+L3+L4+L5+L6+L7+
L8+...+L11+a+b+c+d+e+f+
≤560m
g+h+i+...+m+n
L1+L2+L3+L4+L5+e or
≤150m
L1+L6+L7+L8+L9+L10+n
≤175m
(Refer to Requirement 1)
L2+L3+L4+L5+e or
L6+L7+L8+L9+L10+n
≤40m/90m
(Refer to Requirement 2)
≤50m
H (Refer to Requirement 3)
≤40m
h
≤30m
3. Requirement 3:
The largest level difference between
indoor unit and outdoor unit should not exceed 50m
(if the outdoor unit is above) or 40m (if the outdoor
unit is below). Additionally: If the outdoor unit is
above and the level difference is greater than 20m, it
is recommended that an oil return bend with
dimensions as specified in Figure 4.11 is set every
10m in the gas pipe of the main pipe.
R
R
D
Table 4.4
Φ19.1 Φ22.2 Φ25.4 Φ28.6 Φ31.8 Φ38.1
D
R
≥31
≥45
H
≥300
Φ41.3
Φ44.5
Φ50.8
D
R
≥80
H
≥500
4.3.3 Piping diameter
1) Select the diameter of the main piping
▪ The main pipe (L1) and first indoor branch joint (A)
should be sized according to the Table 4.5 and Table
4.6.
Piping
D
Fig 4.11
Unit: mm
≥60
Φ54.0
Φ63.5
≥90
V.1
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