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While there are no floor area limitations for refrigerant charges of less than 1.23 kg, the minimum
floor area [A
A
=
min
A
= minimum floor area (m
min
m
=
refrigerant charge (kg)
c
h
=
height factor (mounting position):
0
– 0.6 for floor-mounted
– 1.8 for wall-mounted
– 1.0 for window-mounted
– 2.2 for ceiling mounted
LFL= R32 Lower Flammability Limit
(0.307 kg/m
Note
The refrigerant charge amount ([mc]) must be calculated by the following formula:
[m
] = [1] + [2] = [1] + ([3] * ([4] – [5]))
c
where:
[1]: refrigerant charged at shipment
[2]: refrigerant charge amount in the field
[3]: additional charge per 1 m
1) If the total pipe length is within the maximum value of the charge-less pipe length, refrigerant charge in the field is unnecessary.
Calculating examples
Using the above formula, it is possible to calculate
a) the minimum floor area for a given refrigerant charge, or
b) the maximum refrigerant charge allowed for a given floor area.
2.5 m
AHU Kit – Installation Instructions – 11/2021
] for larger refrigerant charge amounts can be calculated by the following formula:
min
[
]
2
m
c
2.5 x LFL
x h
5/4
0
)
2
)
3
1
2.2 m
10,0 m
2
General information and safety notes
ceiling-mounted
8.0
7.0
wall-mounted
6.0
5.0
4.0
3.0
2.0
1.0
0.0
0.0
50.0
100.0
Floor area (m
[4]: total pipe length
[5]: max. charge-less pipe length
Example:
S-6071PF3E + U-71PZH3E5
6.8 kW, 7 m piping length
1.95 kg refrigerant charge
a) A given refrigerant charge amount of 1.95 kg
requires a minimum floor area of 2.41 m2.
b) For a given floor area of 10 m
refrigerant charge amount is 3.97 kg.
Refrigerant charge:
1.95 kg
floor-mounted
150.0
200.0
250.0
)
2
the maximum
2
11
1
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