Hitachi UTOPIA RASC Series Installation And Operation Manual page 14

SYSTEM DESCRIPTION
Start-up and Operation: Check to ensure that all the stop
valves are fully opened and no obstacle exists at the inlet/outlet
sides before start-up and during the operation.
Maintenance: Periodically check the high pressure side
pressure. If the pressure is higher than the maximum allowable
pressure, stop the system and clean the heat exchanger or
remove the cause.
Maximum Allowable Pressure and High Pressure Cut-out
Value:
Unit Model Refrigerant
RASC-3HVRNE
RASC-5HVRNE R410A
RASC-10HRNE

NOTE:
The label for the vessel under PED are attached on the
high pressure vessel. The pressure vessel capacity and
vessel category are indicated on the vessel.
Location of High Pressure Switch
3. SYSTEM DESCRIPTION
This air conditioner consists of one RASC unit and one indoor
unit with one remote control switch (hereafter called "system").

NOTE:
In case of twin, triple and quad system it consists in one
RASC unit, and two, three or four Indoor Units with one
remote control switch.
This air conditioner is designed to offer cooling, heating, dry and
fan operation.
This operation mode is controlled by the remote control switch.
4. BEFORE OPERATION

CAUTION:
Supply electrical power to the system for approximately
-
12 hours before start-up or a long shutdown. Do not
start the system immediately after power supply, it may
cause a compressor failure because the compressor is
not heated well.
When the system is started after a shutdown longer that
-
approximately 3 months, it is recommended to check
the system by your service contractor.
Maximun
High Pressure
Allowable
Switch Cut-out
Pressure
Value (MPa)
(MPa)
4.15 4.00 ~ 4.10
High pressure
switch
compressor

NOTE:
The high pressure switch is indicated on the electrical wir-
ing diagram in the RASC unit as PSH connected to printed
circuit board (PCB1) in the RASC unit.
Structure of High Pressure Switch
Contact Point
Electrical wire

DANGER:
Do not change the high-pressure switch locally or change
−
the high pressure cut-out set value locally. If changed, it
will cause serious injury or death due to explosion.
Do not attempt to turn service valve rod beyond its stop.
−
Turn OFF the main switch when the system is to be
-
stopped for a long period of time: If the main switch is
not turned OFF, electricity will be used, because the oil
heater is always energised during compressor stopping.
Make sure that the RASC unit is not covered with
-
snow or ice. If covered, remove it by using hot water
(approximately 50°C). If the water temperature is higher
that 50°C, it will cause damage to plastic parts.
PMML0140A rev.1 - 07/2009
Pressure Detected
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