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PAW-VP•LDHW - Technical Manual – 2020-07
Tubing Data and Refrigerant
5
5.3 Calculation of the refrigerant charge
How to calculate refrigerant charge
Example 1:
Indoor Unit:
PAW-VP1000LDHW
Outdoor unit:
U-250PE2E8A
Pre charge
[kg]
6.4
Total pipe length (one way):
[m]
20
Attention: follow instruction
[g]
Remove 1400 g for pipe length 7.5 m
Required additional refrigerant over 7,5 meters
[g]
45
How to calculate:
1. Total pipe length 20 m; remove length 7.5 m
2. Calculation of correction pipe length: 20 m – 7.5 m = 12.5 m
3. Refrigerant amount:
a. Pipe length refrigerant amount: 12.5 m * 45 g/m = 562.5 g
b. Remove for pipe length up to 7.5 m: = 1400 g
c. Refrigerant amount to remove: 1400 g – 562.5 g = 837.5 g
The refrigerant amount to remove is
837 g
.
Example 2:
Indoor Unit:
PAW-VP1000LDHW
Outdoor unit:
U-250PE2E8A
Pre charge
[kg]
6.4
Total pipe length (one way):
[m]
5
Attention: follow instruction
[g]
Remove 1400 g for pipe length 7.5 m
Required additional refrigerant over 7,5 meters
[g]
45
How to calculate:
1. Total pipe length 5 m; remove length 7.5 m
2. Remove for pipe length up to 7.5 m: =
-1400 g
If total pipe length less than 7.5 m the refrigerant charge is good after correction, no need to
make calculation. Minimum pipe length is 5 m.
5.4 Temperature loss by refrigerant pipe length
Use suitable insulation: For outdoor use, make sure it is weatherproof, UV-resistant and pro
-
tected against damage. The thicker the insulation, the lower the heat loss.
Wall thickness of the insulation Liquid tube > 10 mm; Gas tube > 19 mm
If the discharge pipe is well insulated between the heat pump and the tank, the heat loss is ap
-
proximately 0.2 ˚C per meter (one way).
