21
4 Requirement 4: The largest level difference between
indoor units should not exceed 40m.
Table 4.4. Pipe size allowable increase diameters (mm)
Φ9.52 to Φ12.7 Φ12.7 to Φ15.9 Φ15.9 to Φ19.1
Φ19.1 to Φ22.2 Φ22.2 to Φ25.4 Φ25.4 to Φ28.6
Φ28.6 to Φ31.8 Φ31.8 to Φ38.1 Φ38.1 to Φ41.3
Φ50.8 to Φ54.0
Φ41.3 to Φ44.5 Φ44.5 to Φ50.8
3. Requirement 3: The largest level difference between
indoor unit and outdoor unit should not exceed 110m
(if the outdoor unit is above) or 110m (if the outdoor
unit is below). Additionally: (i) 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 4.8 be set every
10m in the gas pipe of the main pipe; and (ii) if the
level difference is more than 40m (outdoor unit is
below) or 50m (outdoor unit is above), the size of the
main pipe (L1) should be increased as Table 4.7.
Table 4.3 Summary of permitted refrigerant piping lengths and level differences
1. Requirement 1: The piping between the farthest
indoor unit (N11) and the first outdoor branch joint (L)
should not exceed 220m (actual length) and 260m
(equivalent length). (The equivalent length of each
branch joint is 0.5m, and the equivalent length of
each branch header is 1m.)
2. Requirement 2: The piping between the farthest
indoor unit (N11) and the first indoor branch joint (A)
should not exceed 40m in length (Ʃ{L6 to L10} + k) ≤
40m) unless the following conditions are met and the
following measures are taken, in which case the max
permitted length is 120m.
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 k each ≤ 40m).
b) The difference in length between {the piping from the
first indoor branch joint (A) to the farthest indoor unit
(N11) and {the piping from the first indoor branch joint
(A) to the nearest indoor unit (N1) does not exceed
40m. That is: (L6+L7+L8+L9+L10+k) – (L2+a)≤40m.
Measures:
a) Increase the diameter of the indoor main 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.
H
R
D
H
R
D
D
R
H
≥31
≥300
≥45 ≥60 ≥80
≥500
≥90
Φ19.1 Φ22.2 Φ25.4 Φ28.6 Φ31.8 Φ38.1 Φ41.3 Φ44.5 Φ50.8 Φ54.0 Φ63.5
Unit: mm
Table 4.5
Figure 4.8
The piping length and level difference requirements that
apply are summarized in Table 4.3 and are fully
described as follows.
Actual length
L6+L7+L8+L9+L10+k
Outdoor unit is above
Outdoor unit is below
Total piping length
Category Permitted values Piping
Piping lengths
Level differences
Piping between the farthest
indoor unit and the first
outdoor branch joint
Piping between outdoor unit
and outdoor branch joint
Piping between the farthest indoor unit and the first
indoor branch joint
Largest level difference
between the indoor unit and
outdoor unit
Largest level difference between indoor units
Equivalent length
Actual length
≤1100m
≤220m
≤260m
≤10m
≤40(120)m
≤110m
≤40m
L1+∑(L2 to 10)x2+∑(a to k)
L1+L6+L7+L8+L9+L10+k
g1≤10m, g2+G1≤10m,
g3+G1≤10m
(Refer to Requirement 3)
(Refer to Requirement 1)
(Refer to Requirement 4)
(Refer to Requirement 2)
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