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12 - WATER CONNECTIONS
For size and position of the unit water inlet and outlet connections
refer to the certified dimensional drawings supplied with the unit.
The water pipes must not transmit any radial or axial force to the
heat exchangers nor any vibration.
The water supply must be analysed and appropriate filter-ing,
treatment, control devices, shut-off and bleed valves and circuits
built in, to prevent corrosion (example: damage to the protection
of the tube surface if the fluid is polluted), fouling and deterioration
of the pump fittings.
Before any start-up verify that the heat exchange fluid is compatible
with the materials and the water circuit coating.
In case additives or other fluids than those recommended by
Carrier are used, ensure that the fluids are not considered as a
gas, and that they belong to class 2, as defined in directive
2014/68/EU.
The pumps in the hydraulic module are compatible with 40%
propylene glycol and 40% ethylene glycol. But if these fluids are
used, the pump fittings need to be replaced more frequently (every
15000 operating hours instead of 25000 hours for an appliacation
using water).
Carrier recommendations on heat exchange fluids:
•
No NH
4+
ammonium ions in the water, they are very
detrimental for copper. This is one of the most important
factors for the operating life of copper piping. A content of
several tenths of mg/l will badly corrode the copper over
time.
•
Cl
-
Chloride ions are detrimental for copper with a risk of
perforations by corrosion by puncture. If possible keep
below 125 mg/l.
•
SO
4
2-
sulphate ions can cause perforating corrosion, if their
content is above 30 mg/l.
•
No fluoride ions (<0.1 mg/l).
•
No Fe
2+
and Fe
3+
ions with non negligible levels of dis-
solved oxygen must be present. Dissolved iron < 5 mg/l
with dissolved oxygen < 5 mg/l.
•
Dissolved silica: silica is an acid element of water and can
also lead to corrosion risks. Content < 1mg/l.
•
Water hardness: >0.5 mmol/l. Values between 1 and 2.5
mmol/l can be recommended. This will facilitate scale
deposit that can limit corrosion of copper. Values that are
too high can cause piping blockage over time. A total
alkalimetric titre (TAC) below 100 is desirable.
•
Dissolved oxygen: Any sudden change in water oxygenation
conditions must be avoided. It is as detrimental to
deoxygenate the water by mixing it with inert gas as it is to
over-oxygenate it by mixing it with pure oxygen. The
disturbance of the oxygenation conditions encou-rages
destabilisation of copper hydroxides and enlarge-ment of
particles.
•
Electric conductivity: 0.001-0.06 S/m (10-600 µS/cm).
•
pH: Ideal case pH neutral at 20-25°C (7 < pH < 8).
ATTENTION: Charging, adding or draining fluid from the water
circuit must be done by qualified personnel, using air vents
and materials suitable for the products. Water circuit charging
devices are field-supplied. Charging and removing heat
exchange fluids should be done with devices that must be
included on the water circuit by the installer. Never use the
unit heat exchangers to add heat exchange fluid.
12.1 -
Operating precautions and recommendations
The water circuit should be designed to have the least number of
elbows and horizontal pipe runs at different levels. Below the main
points to be checked for the connection:
•
Comply with the water inlet and outlet connections shown
on the unit.
•
Install manual or automatic air purge valves at all high points
in the circuit.
•
Use a pressure reducer to maintain pressure in the circuit(s)
and install a relief valve as well as an expansion tank. Units
with the hydraulic module include a relief valve and an
expansion tank.
•
Install thermometers in both the entering and leaving water
connections.
•
Install drain connections at all low points to allow the whole
circuit to be drained.
•
Install stop valves, close to the entering and leaving water
connections.
•
Use flexible connections to reduce vibration transmission.
•
Insulate all pipework, after testing for leaks, both to reduce
thermal leaks and to prevent condensation.
•
Wrap the insulations with a demisting screen.
•
If the external unit water pipes are in an area where the
ambient temperature is likely to fall below 0°C, they must
be protected against frost (frost protection solution or electric
heaters).
•
The use of different metals on hydraulic piping could
generate eletrolytic pairs and consequently corrosion. It
could be needed to add sacrificial anodes.
NOTE: For units not equipped with a hydraulic module a
screen filter must be installed. This must be installed on the
water entering pipes upstream of the pressure gauge and
close to the unit heat exchanger. It must be located in a
position that is easily accessible for removal and cleaning.
The mesh size of the filter must be 1.2 mm.
The plate heat exchanger can foul up quickly at the initial unit
start-up, as it complements the filter function, and the unit
operation will be impaired (reduced water flow rate due to
increased pressure drop).
Units with hydraulic module are equipped with this type of
filter.
Do not introduce any significant static or dynamic pressure
into the heat exchange circuit (with regard to the design
operating pressures).
The products that may be added for thermal insulation of the
containers during the water piping connection proce-dure
must be chemically neutral in relation to the materials and
coatings to which they are applied. This is also the case for
the products originally supplied by Carrier.
ATTENTION: Use of units in an open loop is forbidden.
12.2 -
Hydraulic connections
The hydraulic circuit diagram shows a typical hydraulic 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 hydraulic 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 hydraulic circuit
components is guaranteed:
•
Down to -20°C by electric heaters (heat exchanger and
internal piping) that have an automatic supply (units without
hydraulic module),
•
Down to 0°C by an electric heater on the heat exchanger
that has an automatic supply and by pump cycling (units
with hydraulic 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 hydraulic
module and “Reinforced frost protection” option).
Never switch off the water heat exchanger and hydraulic 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.