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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 hydronic 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
ammonium ions in the water, they are very
4+
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
sulphate ions can cause perforating corrosion, if
2-
4
their content is above 30 mg/l.
•
No fluoride ions (<0.1 mg/l).
•
No Fe
and Fe
ions with non negligible levels of dis-solved
3+
2+
oxygen must be present. Dissolved iron < 5 mg/l with
dissolved oxygen < 5 mg/l.
•
Dissolved silicon: silicon 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).
32
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 safety valve as well as an expansion
tank. Units with the hydronic module include a safety
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 hydronic 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 hydronic 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.
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