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9 - SYSTEM INITAL START-UP
9.3 - Essential points to check
9.3.1 - Compressors
Ensure that each compressor is rotating in the correct direction,
by checking that the discharge temperature rises quickly, the HP
increases and the LP drops. If it is rotating in the wrong direction,
the electric power supply is incorrectly wired (reversed phases).
To ensure rotation in the correct direction, swap two power supply
phases.
■ Check the compressor discharge temperature with a contact
sensor
■ Check the input current; it should be normal
■ Check all safety devices to make sure they operate correctly
9.3.2 - Hydraulics
As the exact total system pressure drop is not known at
commissioning, adjust the flow of water with the control valve until
the desired nominal rate is obtained.
By modifying the pressure drop in the hydraulic network, the control
valve aligns the system pressure/flow curve with that of the pump
so that the nominal flow rate corresponding to the desired operating
point is obtained. The pressure drop in the water exchanger (read
using the pressure gauge placed on the exchanger inlet and outlet)
is the reference to be used to check and adjust the nominal flow
rate of the system.
Follow the procedure described below:
■ Open the control valve completely
■ Let the pump run for two hours to flush out any solid particles
in the circuit
■ Read the pressure drop in the water exchanger when the pump
is turned on and then two hours afterwards
■ If the pressure drop has decreased, this means that the screen
filter is clogged. It must be removed and cleaned
■ Repeat until the filter is completely clean
■ If the system pressure drops are above the available static
pressure delivered by the pump, the resulting water flow rate
will be low and the difference in temperature between the
exchanger inlet and outlet will be too high. This is why pressure
drops must be minimised. Check that this difference is within
the values on the curve (refer to the section "Water type heat
exchanger min. water volume and flow rate")
9.3.3 - Refrigerant charge
Each unit is shipped with an exact charge of refrigerant (see the
table of physical properties).
Check that there are no visible refrigerant or oil leaks :
■ No apparent damage on the refrigerant circuit pipes
(no trauma, cracks, deformation)
■ No traces of grease on the connections and refrigerant circuit
sensors.
In case of doubt, use a refrigerant leak detection device suited to
the fluid in the unit.
9.3.4 - Ventilation for electrical cabinets
Check that the air flows from the cooling fans are directed from
the outside of the cabinets to the inside (ensuring fresh air is drawn
towards the inside).
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