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8 - 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.
If the Metallic Protection Grilles option is present with the Pump
option, the grille must be cut in order to make the water connection.
This operation is the responsibility of the installer.
The piping must not transmit any axial or radial force to the
exchangers, or any vibrations.
The water must be analysed and the circuit must include the
elements required for 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 energy transfer fluid is compatible
with the hydraulic circuit materials and coating. Where additives or
fluids other than those recommended by the manufacturer are used,
ensure that these are not considered gases, and that they are
class 2, as defined in directive 2014/68/EU.
Manufacturer's recommendations concerning heat transfer
fluids:
- No NH
ammonium ions in the water as they are very harmful
4+
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 25 mg/l.
Regarding the desuperheater or total heat recovery options,
the level of chloride ions (Cl-) must be kept below 10 mg/l.
- SO
sulphate ions can cause perforating corrosion, if their
2-
4
content is above 30 mg/l.
- No fluoride ions (< 0.1 mg/l).
- No Fe
and Fe
ions with non-negligible levels of dissolved
2+
3+
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 and 2.5 are
recommended. This will facilitate scale deposits that can limit
the 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. 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 encourages destabilisation of copper
hydroxides and enlargement of particles.
- Electric conductivity 10-600 µS/cm.
- pH: Ideal case pH neutral at 20-25°C (7.5 < pH < 9).
IMPORTANT: Filling, topping up or emptying of the water circuit
must be carried out by qualified personnel using the air bleed
devices and tools and equipment suitable for the products.
The heat transfer fluid should be filled and drained using
devices fitted to the hydraulic circuit by the installer. Never
use the unit heat exchangers to add heat transfer fluid.
34
8.1 - Operating precautions and
recommendations
Before commissioning, check that the hydraulic circuits are
connected to the appropriate heat exchangers.
The water circuit must have as few bends and horizontal sections
at different levels as possible,
Main points to be checked for the connection:
- Make sure that the stainless steel water filter is in the screen
filter. See figure 2.
- Comply with the water inlet and outlet connections shown on
the unit.
- Install manual or automatic vents at all high points in the
circuit.
- Maintain the pressure in the circuit(s) with a pressure-
reducing valve and install a relief valve and an expansion
tank. Units supplied with a hydraulic module include a valve.
The expansion vessel is supplied as an option.
- 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 cold water 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 (antifreeze solution or electric heaters)
- Do not introduce any significant static or dynamic pressure
into the heat exchange circuit (with regard to the design
operating pressures).
- The use of different metals in the hydraulic system may create
galvanic couples and lead to corrosion. Verify the need to
install sacrificial anodes.
- Products used for thermal insulation of recipients during
hydraulic connections must be chemically neutral to the
materials and coatings on which they are applied. All original
materials supplied by the manufacturer comply with this
requirement.
Note:
A screen filter must be installed for units supplied without a
hydraulic module. This must be installed on the 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.
A filter with a mesh opening size of 0.8 mm must be installed at
the heat recovery option exchanger intake.
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