7 - WATER CONNECTIONS
When connecting units to the water distribution pipe work, refer
to the certified dimensional drawings supplied with the unit for the
dimensions and position of the water inlet and outlet connections.
The pipes and tubes should not transmit any axial or radial forces
to the exchangers or any vibrations.
The water must be analysed and the circuit must include provision
of any necessary water treatment: filters, additives, intermediate
exchangers, bleed valves, vents, shut-off valves, etc. depending
on the results, in order to prevent corrosion (e.g. damage to the
surface of the tubes due to impurities in the fluid), fouling and
deterioration of the pump lining.
Before any start-up, check that the heat transfer fluid is compatible
with the hydraulic circuit materials. Where additives or other fluids
than those recommended by Carrier are used, ensure that these
are not considered gases, and that they are class 2, as defined
in directive 2014/68/EU.
Carrier's recommendations concerning heat transfer fluids:
-
No NH
4
+
ammonium ions in the water - these are very harmful
to 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 also harmful to copper with a risk of
perforating corrosion. Keep at a level 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 if non-negligible levels of dissolved
oxygen are 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 < 1 mg/l.
-
Water hardness: >0.5 mmol/l. Values between 1 and 2.5
mmol/l are 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 mg/l is desirable.
-
Dissolved oxygen: Avoid any sudden change in water
oxygenation conditions. Deoxygenating the water by mixing
it with inert gas and over-oxygenating it by mixing it with pure
oxygen are both equally harmful. The disturbance of
oxygenation conditions encourages destabilisation of copper
hydroxides and precipitation of particles.
-
Electric conductivity 10-600 µS/cm.
-
pH: Ideal case pH neutral at 20-25°C (7.5 < pH < 9).
CAUTION: Filling, topping up or emptying the water circuit
must be carried out by qualified personnel using tools and
equipment suitable for the products. The heat transfer fluid
should be filled using devices fitted to the hydraulic circuit
by the installer.
7.1 -
Operating precautions and recommendations
Before any system start-up, verify that the hydraulic circuits are
connected to the appropriate heat exchangers. The water circuit
should be designed to have the least number of elbows and
changes in elevation; the main points to be checked for the
connection are listed below.
-
Ensure that the stainless steel water filter is present in the
screen filter. See figure 2.
-
Ensure the water outlet and inlet connections match those
marked on the unit.
-
Install manual or automatic air purge valves at all high points
in the circuit.
-
Maintain the pressure of the circuit(s) with pressure-reducing
valves and install a relief valve and an expansion vessel.
Units supplied with a hydraulic module include a valve. Units
supplied with option 293 include an expansion tank.
-
Install thermometers in both the water inlet and outlet pipes.
-
Install drain connections at all low points to allow the whole
circuit to be drained.
-
Install shut-off valves close to the water inlet and outlet
connections.
-
Use flexible connections to reduce the transmission of
vibrations.
-
Insulate the pipework, after testing for leaks, to prevent heat
transmission and condensation.
-
Cover the insulation with a vapour barrier. If the water pipes
outside the unit pass through an area where the ambient
temperature is likely to fall below 0°C, it must be protected
against frost (anti-freeze solution or electric heaters).
-
The use of different metals in the hydraulic system may create
galvanic couples and lead to corrosion. Verify then the need
to install sacrificial anodes.
-
Do not introduce significant static or dynamic pressure, as
compared to the stated operating pressures, into the heat
transfer fluid circuit.
-
Products used for thermal insulation must be chemically
neutral to the surfaces on which they are applied. All original
materials supplied by Carrier comply with this requirement.
NOTE: A screen filter must be installed for units supplied
without a hydraulic module. This must be installed on the
unit's water inlet pipe, upstream of the pressure differential
gauge and close to the unit heat exchanger. It must be located
somewhere easily accessible to enable disassembly and
cleaning. The mesh size of the filter must be no more than
1.2 mm. If the filter is missing, the plate heat exchanger can
quickly become fouled during the first start-up, as it will trap
any debris in the system, and correct unit operation will be
affected (reduced water flow rate due to the increased
pressure drop).
Units with a hydraulic module are equipped with this type of filter.
28
Summary of Contents for Carrier 30RQM 160
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