CIAT aquaciat 2 LD Serie Handbuch Seite 43

Start up
- The unit must be switched on and started up by a qualified
engineer.
- Start-up and operating tests must be performed with a
thermal load and water circulation in the exchangers.
- Apply power to the main board.
- Make sure that the machine is configured for local control
(selected at regulator)
- Use the button to select the operating mode
as chilled water or hot water unit).
- Adjust the chilled water and hot water setpoints.
- Press the on/off button to start the unit
- The internal safety devices are active. If a safety device
triggers, locate the fault, reset the safety device if necessary
and press the RESET button at the control panel to
acknowledge the fault.
- The unit cannot be started up for a period of 2 minutes (time
required for all the safety devices to be identified and
registered). The control stages are activated in series as a
function of demand.
To shut down the unit other than in emergency situations,
it is necessary to use:
– either the On/Off switch at the control panel
– or a potential-free contact at the automaticity control.
Do not use the master switch because the electrical panel
must continue to be powered (antifreeze protection,
crankcase heater).
NOTE:
AQUACIAT models are machines which operate with R410A; it
is essential for engineers to use equipment which is compatible
with R410A which has a working pressure approximately 1.5
times greater than machines operating with R22 or R407C.
Essential points to be checked
- Make sure that each compressor is rotating in the right
direction by checking that the outlet temperature rises quickly,
that the HP increases and that the LP falls. If the direction of
rotation is incorrect, this is due to the incorrect cabling of the
electrical power supply (phase reversal). To obtain the correct
direction of rotation, reverse the two power supply phases.
- Check the outlet temperature of the compressor(s) using a
contact sensor
- Make sure that the absorbed current is normal
- Check the functioning of all the safety devices
Adjustment of the water flow
Since the overall pressure loss of the installation is not known
precisely at the time of commissioning, it is necessary to adjust
the water flow with the adjusting valve in order to obtain the
desired nominal flow.
In effect, because of the pressure loss it generates in the
hydraulic network, this adjusting valve makes it possible to lock
the pressure/network flow curve to the pressure/pump output
curve and thus obtain the nominal flow corresponding to the
desired operating level.
The value read for the pressure loss in the plate exchanger
(obtained using the pressure gauge connected to the
exchanger's input and output) is then used to monitor and
regulate the installation's nominal flow.
Respect the procedure described below:
- Fully open the adjusting valve
- Allow the pump to run for 2 hours in order to eliminate any
solid particles which may be present in the circuit
- Record the pressure loss at the plate exchanger on pump
start-up and 2 hours afterwards
- If the pressure loss drops, this means that the screen filter is
clogged. It is necessary to dismount and clean it.
- Continue the process until the filter is no longer clogged
(operation - Once the circuit has been cleared of contaminants, measure
the pressure loss at the plate exchanger and compare it to the
theoretical pressure loss of the selection.
If the pressure loss is greater than the theoretical loss then the
flow is too great. The pump output is therefore too high given
.
the pressure loss in the installation. In this case, close the
adjusting valve one turn and read the new pressure loss.
Repeat the operation and close the valve each time until the
nominal flow is obtained at the desired operating point.
In contrast, if the pressure loss in the network is too high
compared to the available static pressure supplied by the
pump, the resulting water flow will be reduced and the
temperature difference between the exchanger's inlet and
outlet will increase, thus making it necessary to minimise the
pressure losses.
Checking the refrigerant fluid load
The units are shipped with a precise refrigerant fluid load.
To make sure that the refrigerant fluid load is correct, perform
the following checks with the unit operating at full capacity:
- check that no gas bubbles appear in the liquid sight glass
- check the real sub-cooling value at the condenser outlet. This
should be between 5 and 8°C depending on the type of unit.
Measurement in air conditioning operation for ILD units
If there is a significant volume of fluid missing, large bubbles
can be seen in the sight glass liquid, the suction pressure falls
and there is a high level of overheating at the compressor
intakes. After the leak has been detected and the machine's
refrigerant load has been completely drained using a recovery
unit, the machine must be refilled. Perform the necessary
repairs, test for watertightness while making sure that the
maximum working pressure at the low pressure side is not
exceeded and refill the unit.
Refilling must be performed in liquid phase at the liquid valve.
The quantity of refrigerant fluid introduced into each circuit in
the unit must correspond to the values indicated on the type
plate.
The same operations should be performed if the sub-cooling
value is less than the specified values.
NOTE: When the unit is started, an excessively low suction
pressure or excessively high condensing pressure may be
observed. There are various possible causes for these
problems - see the section Analysis of operating anomalies.
If the operating mode is inverted
To optimise the operation of the unit, it is essential to:
- adjust the refrigerant load.
- optimise the adjustment of the expansion valve.
- adjust the safety parameters of the regulator to correspond to
the operating mode.
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