30
For both option A (Figure 22) and option B (Figure 23) the
following conditions should be observed:
-
The maximum speed permitted in any line is 15 m/s.
-
Suction line must be insulated and have a 2% slope towards
the compressor and the horizontal pipe run.
-
In long pipe runs it may be necessary to adjust the oil charge.
-
If the liquid line flow is downward, it is necessary to
install pressure equalizer for heights above 10 m.
-
The liquid should be subcooled by at least 1 K at the
restrictor inlet. In this case, if the liquid line flow is
upward and the pipe is longer than 15 m, it must be
subcooled by 1 K for each 3.5 m in excess of 15 m.
-
Subcooling can be contained in the liquid and suction
lines (maximum 15 m) of the units.
-
For each metre of refrigerant pipe installed, refrigerant has
to be added in accordance with table 3.
Table 3 - Refrigerant charge (g/m)
Diameter
1/2"
5/8"
3/4"
7/8"
1-1/8"
1-3/8"
Liquid line
75
120
180
250
420
645
Suction line
14
23
34
47
81
123
Sizing
Suction/discharge line
The gas line is the suction line in cooling and the discharge
line in heat pump operation. Its diameter is calculated for the
most unfavourable condition. This can be as a suction or as a
discharge line and has to be checked afterwards for the other
line type.
For example, in the configuration shown in option A (the suction
speed will produce the most unfavourable condition, and the
gas line diameter will be calculated for suction. Afterwards, the
calculation should be checked for discharge. The diameter
calculation for suction and discharge lines is done in the same
way using the corresponding drawing (see Figs. 24 and 25).
Fig. 24 - Suction line
Fig. 25 - Discharge line
Legend:
38VZ/PZ 015 + 40PZ 015
38VZ/PZ 031 + 40PZ 031
38VZ/PZ 040 + 40PZ 040
38VZ/PZ 025 + 40PZ 025
38VZ/PZ 045 + 40PZ 045
38VZ/PZ 030 + 40PZ 030
38VZ/PZ 055 + 40PZ 055
38VZ/PZ 065 + 40PZ 065
38VZ/PZ 075 + 40PZ 075
Legend:
38VZ/PZ 015 + 40PZ 015
38VZ/PZ 031 + 40PZ 031
38VZ/PZ 040 + 40PZ 040
38VZ/PZ 025 + 40PZ 025
38VZ/PZ 045 + 40PZ 045
38VZ/PZ 030 + 40PZ 030
38VZ/PZ 055 + 40PZ 055
38VZ/PZ 065 + 40PZ 065
38VZ/PZ 075 + 40PZ 075
From Figures 24 and 25, for the selected unit we can obtain the
pressure drop corresponding to 10 m of equivalent length for
each diameter.
For other equivalent lengths, the pressure drop is obtained in
direct proportion. The total pressure drop for the line (sum
corresponding to the vertical and horizontal pipe runs) must
not be higher than 20 kPa.
Liquid line:
The liquid line diameter can be selected using table 4.
Table 4 - Liquid line
Models
Total equivalent length
Up to 10 m
From 10-30 m
From 30-50 m
38VZ/PZ 015 + 40PZ 015
5/8"
5/8"
5/8"
38VZ/PZ 025 + 40PZ 025
5/8"
5/8"
3/4"
38VZ/PZ 030 + 40PZ 030
5/8"
3/4"
3/4"
38VZ/PZ 031 + 40PZ 031
5/8"
5/8"
5/8"
38VZ/PZ 040 + 40PZ 040
5/8"
5/8"
5/8"
38VZ/PZ 045 + 40PZ 045
5/8"
5/8"
3/4"
38VZ/PZ 055 + 40PZ 055
5/8"
3/4"
3/4"
38VZ/PZ 065 + 40PZ 065
5/8"
3/4"
7/8"
38VZ/PZ 075 + 40PZ 075
3/4"
7/8"
7/8"
Necessary checks/precautions before start-up
-
Ensure that all electrical connections are properly
tightened.
-
Ensure that the unit is level and well-supported.
-
Check the condition of the ductwork in case damage has
occurred during installation.
-
The air filter should be clean and in place.
-
All the panels should be fitted and firmly secured with the
corresponding screws.
-
Make sure that there is sufficient space for servicing and
maintenance purposes.
SPEED (m/s)
SPEED (m/s)