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12 - WATER CONNECTIONS
To ensure frost protection of the units with hydraulic module water
circulation in the water circuit must be maintained by periodically
switching on the pump. If a shut-off valve is installed, a bypass
must be included as shown below.
Winter position
Unit
Open
IMPORTANT: Depending on the atmospheric conditions in
your area you must do the following when switching the unit
off in winter:
• Add ethylene glycol or propylene glycol with an
adequate concentration to protect the installation up
to a temperature of 10 K below the lowest temperature
likely to occur at the installation site.
• If the unit is not used for an extended period, it should
be drained, and ethylene glycol or propylene glycol
should be charged in the heat exchanger as a safety
precaution, using the water inlet purge valve connection.
• At the start of the next season, refill the unit with water
and add an inhibitor.
• For the installation of auxiliary equipment, the instal-ler
must comply with basic regulations, especially for
minimum and maximum flow rates, which must be
between the values listed in the operating limit table
(application data).
• To prevent corrosion by differential aeration, the
complete drained heat transfer circuit must be charged
with nitrogen for a period of one month. If the heat
transfer fluid does not comply with the Carrier regu-
lations, the nitrogen charge must be added immediately.
12.4 - Protection against cavitation (option 116)
To ensure the durability of the pumps in the integrated hydraulic
modules, the control algorithm of the 30RQS/RQSY units
incorporates anti-cavitation protection.
It is therefore necessary to ensure a minimum pump entering
pressure of 60 kPa (0.6 bar) during operation and at shut-down.
A pressure below 60 kPa will prohibit unit start-up or cause an
alarm with the unit shutting down. In order to obtain sufficient
pressure, it is recommended:
• to pressurise the hydraulic circuit between 100 kPa and 400
kPa (1 and 4 bar) maximum on the suction side of the pump,
• to clean the hydraulic circuit before charging water (see
chapters 13.2, 13.3 and 13.4),
• to regularly clean the screen filter,
Closed
Water
network
Closed
35
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