MSAT 102-122-142-162-182-202-242

CHECKING FOR LEAKS
- Carefully check that the valves on the condensing units are closed.
- Connect the pressure gauge assembly to the service test points on the valves.
- Pressurise with refrigerant to 250KPa.
- Close the valves on the pressure gauge assembly, then disconnect the
refrigerant bottle and subsequently connect the nitrogen bottle.
- Open the valves on the pressure gauge.
- Pressurise the system with nitrogen to 1200KPa.
- Carefully check all the pipes using a leak detector or other electronic
instrument, with special attention to the welds and joints in general.
If the necessary equipment is not available, make sure any parts that may give
rise to refrigerant leaks (welds, joints etc.) are accessible.
OUTDOOR UNIT
INDOOR UNIT
Thermostat bulb
Max. height difference
Thermostat bulb
Gas valve
Figure Figura 5 5
Liquid valve
INSTRUCTIONS FOR CORRECT CONNECTION
INTAKE PIPE
- Slope this towards the compressor in the horizontal sections (0.5 %) to ensure
the return of oil to the compressor even under minimum load conditions.
- Carefully insulate the pipe with anti-condensate, closed cell polyethylene,
minimum thickness 9mm.
- If the condensing unit is lower than the evaporating unit (figure 5), install a drain
trap of equal height to the exchanger coil, so as to prevent the return of liquid to
the compressor when the unit is off.
- To avoid fitting a drain trap, install a solenoid valve on the liquid line (see
Figure 6); this is always recommended in any case.
- If the terminal unit is fitted with a thermostat as well as a drain trap, install a
socket (see Figure 5) as near as possible to the unit. This will prevent the bulb of
the thermostat from remaining in contact with the liquid when the unit is off (see
Figure 5).
In the case of connection to our CED-V terminal units, the drain trap is already
fitted inside the unit.
- If the condensing unit is higher than the evaporating unit, only install the socket
(see Fig 7). Note that if the total distance exceeds 7-10 metres, the solenoid
valve must be installed on the liquid line.
- For vertical rises, as well as well the socket also fit an oil collection trap every 6
metres (see Figure 8).
- Use wide-radius curves (no elbows).
- Carefully avoid choking the pipes.
LIQUID PIPES
- If exposed to the sun or passing through areas where the temperature is higher
than the outside temperature, they must insulated, otherwise they can be free.
- Avoid excessive diameters so as to prevent an excess refrigerant charge.
Max. height difference
Figure 6
Figura 6
Figure 7
Figura 7
8 metres
Figure Figura 88
IMPORTANT
When the indoor terminal unit is fitted with a thermostat, if the connection pipes are longer than around 15/20 metres or
alternatively if the system is expected to operate in variable climatic conditions (for example, very different Day/Night outside
air temperature) a liquid receiver of suitable capacity should be installed near the indoor unit.
The liquid receiver performs the following functions:
- It prevents gaseous freon form reaching the expansion device.
- It compensates for the variations in charge that occur in the system due to the change in operating conditions.
- For a certain time it partly compensates for any immeasurable microscopic leaks that occur in the system over time.
- It prevents the excessive flooding of the condenser with the corresponding raising of the condensing temperature/pressure
if the system has been charged with a higher quantity of refrigerant, or if the system was charged in abnormal climatic
conditions.
Having said this, the liquid receiver should always be installed when the connections are very long.
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