System design recommendations
For the initial charge condensing must not run
and eventual service valves must be closed.
Charge refrigerant as close as possible to the
nominal system charge before starting the
compressor. As maximum safe refrigerant charge
for compressor is 3,6 kg initial charge can be
considered close to 4 kg (will depend on tube
sizes, lengths of each individual system). This initial
charging operation must be done in liquid phase
as far away as possible from the compressor.
Never start the compressor under vacuum, ensure
a progressive charge of the system to 4– 5 bar.
For the initial refrigerant charge service port on
liquid line ball valve can be used. This port is
equipped with Schrader valve.
For the adjustment of refrigerant charge port on
the suction line can be used (located between oil
return port and suction ball valve port). This port is
also equipped with Schrader valve.
Refrigerant charge should secure stable work
at minimum and maximum heat load within
the limits of condensing unit application
envelope!
The remaining charge is done until the installation
has reached a level of stable nominal condition
during operation.
Next steps can be followed for proper charging or
the system:
- keep system working under the max load
conditions (all evaporators working, maximum
air/liquid flow via evaporator(s)).
- slowly throttling liquid in on the low pressure
side as far away as possible from the compressor
suction connection by default via the port on
suction line as described before.
- keep under the control evaporating pressure,
condensing pressure, suction superheat.
- charge system until reaching suction superheat
6-12 K at desired evaporating temperature.
Suction superheat as well as suction, condensing
pressures (temperatures) can be read from
controller display.
To avoid system overcharging (which can cause
higher energy consumption, high pressure alarms)
maximum refrigerant charge can be calculated as
follows:
Mmax = (Vrec + VliqL) * 0.9,
Where
Mmax = approximate maximum refrigerant
charge, kg
Vrec = receiver volume, L, for Optyma
™
Plus
INVERTER 6,2 L
VliqL = internal volume of liquid line, L (specific for
each system)
0.9 – correlation coefficient due to refrigerant
density.
Liquid line – Dimension
Liquid line - Volume
OD
[inch]
OD [mm] ID [mm]
VliqL
[L/1m]
VliqL
[L/10m]
3/8
9.5
7.9
0.05
0.5
1/2
12.7
11.1
0.10
1.0
5/8
15.9
14.1
0.16
1.6
3/4
19.1
17.3
0.23
2.3
7/8
22.2
19.9
0.31
3.1
5.3 Refrigerant charge
28
FRCC.PC.044.A6.02
Application Guidelines
