Hitecsa CLOSE CONTROL CED Série Mode D'emploi page 35

I N S T A L L A T I O N
VACUUM OF THE REFRIGERATION CIRCUIT
The creation of a vacuum is a long process, keep in mind the following points:
- Use only a vacuum pump of which you can be absolutely certain of its efficiency and if in doubt verify the vacuum
created before connecting to the circuit
1 mBar with R22 and at least 0,3 mBar with R407c or R134a should be reached and maintained for at least 1
-
hour (in long circuits, for even longer, until the humidity is less than 10 ppm)
Manometers are not required to check the vacuum.
-
Connect the pump to the two connection points that have been previously prepared.
-
- Start the pump and check that it is turning in the right direction.
- Weigh the pump down at least during the first hour of operation.
- Never leave the installation while the pump is in operation if there is no automatic safety valve fitted, because if the
pump should stop (power cut or other reason) the oil of the
Keep in mind that the vacuum in an installation should reach the levels indicated in section 4.1 and the pump should
-
be left to run for at least another hour and every now and then releasing part of the load.
PREPARING TO LOAD REFRIGERANT INTO THE INSTALLATION
Remember that HITECSA direct expansion units, unless specifically indicated in the order, are always supplied with a full
freon load, therefore any refrigerant required is to complete the load within the pipework in the installation.
To effect this operation, one should proceed as follows:
Fit a manometer on the supply valve of the compressor and give the valve shaft one turn in a clockwise direction.
-
- Connect the cylinder and manometer to the suction valve.
- Eliminate all air from piping between the cylinder and connecting nipple by ejecting gas from the cylinder through the
pipe and loosening slightly the connection between nipple and suction valve.
- Retighten connection to suction valve and, with the cylinder open, effect two full clockwise turns of the shaft of the
compressor suction valve.
WARNING : when the circuit is being filled with R22 or R134a, it is advisable to do this with the refrigerant in gas
-
form in order to avoid emulsifying the oil and liquid return to the compressor valves. Whereas with R407c, since it is a
mixture composed of:
23% R32 (CH 2 F 2 )
25% R125 (CH 3 -CHF 3 )
52% R134a (CF 3 -CH 2 F)
and since these gases are volatile in different degrees one to the other, the circuit must be filled with the refrigerant in
liquid form to ensure that the percentages are as indicated previously.
The refrigerant charge of an air-conditioner should be effected by an expert refrigeration engineer and with the
utmost attention.
- Open the shut-off valves both on the indoor unit as well as the external unit.
IMPORTANT POINTS WHEN STARTING-UP COMPRESSORS
For all those units having compressors with a capacity greater than 2 HP (1,4 kW), it is absolutely necessary, before the
start-up, to effect an initial preheat of the oil contained within the compressor itself.
The duration of this preheat phase should in no circumstances be less than the minimum requirement of 6 hours.
The preheat is effected by turning on the external main switch so that power is supplied to the unit.
During this phase, the controller of the unit itself must be left in the "OFF" position, meaning that the compressor
must not be made to operate.
After the six hour period has elapsed, the compressor can be started up, having made sure that the oil sump is warm to the
touch.
Check that all the electrical connections have been correctly effected, check that terminal screws are tight, check that the
supply voltage is the same as indicated on the identification sticker of the unit, after which the compressor can be started up.
It very probable that the compressor may stop almost immediately after start-up due to intervention of the low pressure
switch since the circuit is only partially loaded.
36
pump will be redrawn into the refrigeration circuit.
05.08 Ref.200989 Rev.100