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12.2 - Hydronic connections
The hydronic circuit diagram shows a typical hydronic
installation. When charging the water circuit use air vents to
evacuate any residual air pockets.
12.3 - Frost protection
The plate heat exchangers, the piping and the hydronic
module pump can be damaged by frost, despite the built-in
anti-freeze protection of the units.
Frost protection of the plate heat exchanger and all hydronic
circuit components is guaranteed:
•
Down to -20°C by electric heaters (heat exchanger and
internal piping) that have an automatic supply (units
without hydronic module),
•
Down to 0°C by an electric heater on the heat exchanger
that has an automatic supply and by pump cycling (units
with hydronic module with or without buffer tank),
•
Down to -20°C by electric heaters (heat exchanger,
internal piping and buffer tank module if present) that
have an automatic supply and by pump cycling (units
with hydronic module and "Reinforced frost protection"
option).
Never switch off the water heat exchanger and hydronic
circuit heaters or the pump, otherwise frost protection can-
not be guaranteed. For this reason the main unit or customer
circuit disconnect switch as well as the auxiliary protection
switch for the heaters must always be left closed.
To ensure frost protection of the units with hydronic 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
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).
Closed
Water
network
Closed
Open
•
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
hydronic 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 hydronic circuit between 100 kPa and
400 kPa (1 and 4 bar) maximum on the suction side of
the pump,
•
to clean the hydronic circuit before charging water (see
chapters 13.2, 13.3 and 13.4),
•
to regularly clean the screen filter,
33
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