Panasonic PAW-160MAH2L Installation Instructions Manual page 41

Product description
Calculation example for total additional refrigerant charge (R32)
Unit: U-60PZ2E5
Pipe length: 40 meter
AHU DX coil (supplied by AHU manufacturer): 1,7 dm
3
Refrigerant charge at shipment fi tted for pipe length within 30 m
Pipes additional refrigerant charge: 0.035 kg/m
AHU DX coil additional refrigerant charge: 0.83 kg/dm
3
Refrigerant charge at shipment is suffi cient for AHU DX coil volume up to 1,4 dm
3
Total additional refrigerant charge calculation
((1.7 dm – 1.4 dm ) x 0.83 kg/dm ) + (10 m x 0.035 kg/m) = 0.249 kg + 0.35 kg = 0.599 kg
3 3 3
Calculation example for number of passes in the heat exchanger
The minimum number of passes in the AHU heat exchanger is restricted. The limit is calculated
by the formula:
Minimum number of passes
= Number of steps × Distance between tube sheets × Number of rows × 1.5 × 10
–4
The calculated value must then be rounded up to the next integer number.
Example
Number of steps: 12
Distance between tube sheets: 1,000 mm
Number of row: 3
Minimum number of passes = 12 × 1,000 x 3 × 1.5 × 10 = 5.4
–4
This value must be rounded up to 6.
This means that the minimum number of passes is 6 passes.
!
NOTICE
Nuisance tripping of high-pressure switch
The outdoor unit is equipped with a high-pressure switch, which stops the operation of the air-
conditioning unit for protection when the set high-pressure limit is exceeded. Nuisance tripping
of the high-pressure switch may occur in heating mode if the heat exchanger pipe thermistor
(E2) is not properly positioned or if the limit is not properly set.
► Position the heat exchanger pipe thermistor (E2) correctly and set the limit properly in
accordance with the instructions given in this document.
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