11
4.3
Permitted
Piping
Lengths
and
Level
Differences
The
piping
length
and
level
difference
requirements
that
apply
are
summarized
in
Table
3
‐
4.3
and
are
fully
described
as
follows
(refer
to
Figure
3
‐
4.2):
1.
Requirement
1:
The
total
length
of
piping
in
one
refrigerant
system
should
not
exceed
1000m.
When
calculating
the
total
length
of
piping,
the
actual
length
of
the
indoor
main
pipes
(the
piping
between
the
first
indoor
branch
joint
and
all
other
indoor
branch
joints,
L
2
to
L
12
)
should
be
doubled.
2.
Requirement
2:
The
piping
between
the
farthest
indoor
unit
(N
9
)
and
the
first
outdoor
branch
joint
(N)
should
not
exceed
175m
(actual
length)
and
200m
(equivalent
length).
(The
equivalent
length
of
each
branch
joint
is
0.5m.)
3.
Requirement
3:
The
piping
between
the
farthest
indoor
unit
(N
9
)
and
first
indoor
branch
joint
(A)
should
not
exceed
40m
in
length
(
Ʃ
{L
7
to
L
10
}
+
i
≤
40m)
unless
the
following
conditions
are
met
and
the
following
measures
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
40m
in
length
(a
to
m
each
≤
40m).
b)
The
difference
in
length
between
{the
piping
from
first
indoor
branch
joint
(A)
to
the
farthest
indoor
unit
(N
9
)}
and
{the
piping
from
the
first
indoor
branch
joint
(A)
to
the
nearest
indoor
unit
(N
1
)}
does
not
exceed
40m.
That
is:
(
Ʃ
{L
7
to
L
10
}
+
i)
‐
(
Ʃ
{L
2
to
L
3
}
+
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,
L
2
to
L
12
)
as
per
Table
3
‐
4.2,
except
for
indoor
main
pipes
which
are
already
the
same
size
as
the
main
pipe
(L
1
),
for
which
no
diameter
increases
are
required.
4.
Requirement
4:
The
largest
level
difference
between
indoor
unit
and
outdoor
unit
should
not
exceed
90m
(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
3
‐
4.1
is
set
every
10m
in
the
gas
pipe
of
the
main
pipe;
and
(ii)
if
the
outdoor
unit
is
below
and
the
level
difference
is
more
than
40m,
the
liquid
pipe
of
the
main
pipe
(L
1
)
should
be
increased
as
per
Table
3
‐
4.2.
5.
Requirement
5:
The
largest
level
difference
between
indoor
units
should
not
exceed
30m.
Table
3
‐
4.2:
Diameter
increase
requirements
Original
(mm)
Increased
(mm)
Φ9.53
Φ12.7
Φ12.7
Φ
15.9
Φ15.9
Φ
19.1
Φ19.1
Φ22.2
Φ22.2
Φ
25.4
Φ25.4
Φ
28.6
Φ28.6
Φ31.8
Φ31.8
Φ
38.1
Φ38.1
Φ
41.3
Φ41.3
Φ44.5
Φ44.5
Φ
54.0
Figure
3
‐
4.1:
Oil
return
bend
(unit:
mm)
300
or
more
300
or
more
