IOM / @DNOVA_THS-0508
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c. Starting operation
Before starting the unit, turn the main switch on, select the operating mode desired from the control panel
and press the "ON" button on the control panel.
If the unit fails to start up, check if the service thermostat has been set according to the nominal values
provided
You should not disconnect the unit from the power supply during periods when it is
inoperative but only when it is to be taken out of service for a prolonged period (e.g. at
the end of the season). To turn off the unit temporarily follow the directions provided in
the section 4.5.
d. Checks during operation
Check the phase sequence relay on the control board to verify whether the phases occur in the correct
sequence: if they do not, disconnect the unit from power supply and invert two phases of the incoming
three-pole cable.
Never
attempt to modify internal electrical connections: any undue modifications will
immediately invalidate the warranty.
e. Checking the refrigerant level
- After a few hours of operation, check whether the liquid level indicator has a green ring: a yellow colour
indicates the presence of humidity in the circuit. In such a case the circuit must be dehumidified by
qualified personnel.
-Large quantities of bubbles should not appear through the liquid level indicator. A constant passage of
numerous bubbles may indicate that the refrigerant level is low and needs to be topped up. The
presence of a few bubbles is however allowed, especially in the case of high-glide ternary mixtures
such as HFC R407C
- Make sure the overheating of the cooling fluid is limited to between 5 and 8 °C: to this end:
1) read the temperature indicated by a contact thermometer placed on the compressor intake pipe;
2) read the temperature indicated on the scale of a pressure gauge likewise connected to the intake
side; refer to the pressure gauge scale for the refrigerant R407C, marked with the initials D.P. (Dew
Point).
The degree of overheating is given by the difference between the temperatures thus determined.
- Make sure that the Sub-cooling of the cooling fluid is limited to between 3 and 5°C: to this end:
1) read the temperature indicated by a contact thermometer placed on the condenser outlet pipe;
2) read the temperature indicated on the scale of a pressure gauge connected to the liquid inlet at the
condenser outlet; refer to the pressure gauge scale for the refrigerant R407C, marked with the
initials B.P. (Bubble Point).
The degree of Sub-cooling is given by the difference between the temperatures thus determined.
Warning: all THS units are precharged with R407C. Any top-ups must be made using the
same type of refrigerant. This operation is to be considered extraordinary maintenance
work and must be performed by qualified personnel only.
Warning: the refrigerant R407C requires “POE” polyolester oil of the type and viscosity
indicated on the compressor rating plate.
For no reason should oil of a different type be introduced into the oil circuit.
