Specifications
18
8.1.2 - Carrier recommendations on heat exchange fluids
The water supply must be analysed and appropriate filter-
ing, treatment and control devices built in to suit the appli-
cation and prevent corrosion, fouling and deterioration of
the pump fittings.
Consult either a water treatment specialist or appropriate
literature on the subject.
• 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. If required, use sacrificial anodes.
• Cl
-
Chloride ions are also detrimental for copper with
a risk of perforations by corrosion by puncture. If
possible keep at a level below 10 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
dissolved 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 < 1 mg/l.
• Water hardness: >0.5 mmol/l. Values between 1.0 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 oxygen-
ation 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.
• Specific resistance – electric conductivity: the higher the
specific resistance, the slower the corrosion tendency.
Values above 30 Ω·m are desirable. A neutral
environment favours maximum specific resistance
values. For electric conductivity values in the order of
20-60 mS/m can be recommended.
• pH: Ideal case pH neutral at 20-25°C
7 < pH < 8
- If the water circuit must be emptied for longer than
one month, the complete circuit must be placed
under nitrogen charge to avoid any risk of corrosion
by differential aeration.
- 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.
For diameters and position of the heat exchanger water inlet
and outlet connections refer to the certified dimensional
drawings supplied with the unit.
The piping must not in any way lead to mechanical
constraints on the heat exchangers.
8.1.1 - General
The fluid to be cooled (often water) must meet the criteria
below.
The hydraulic circuit must be equipped with filters, purges,
vents and unit shut-off valves.
The essential points to verify are:
• 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 an expansion device to maintain pressure in the
circuit.
• Install a safety valve as well as an expansion tank
(included with the hydronic module option).
• Install thermometers in both the entering and leaving
water connections (recommendation).
• 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 the transmission of
vibrations.
• Insulate all pipework, after testing for leaks to prevent
condensation.
• A screen filter must be installed in the water circuit
(included with the hydronic module option). The
mesh size of the filter must be 1.2 mm (see ‘Typical
water circuit’ diagram on the right).
• Before the system start-up verify that the water circuits
are connected to the appropriate heat exchangers.
• Do not introduce any significant static or dynamic
pressure into the heat exchange circuit (with regard to
the design operating pressures).
• 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 recom-
mended 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 97/23/EC.