8 - WATER CONNECTIONS
When connecting units to the water distribution pipe work, refer
to the certied 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-o 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
uid), fouling and deterioration of the pump lining.
Before any start-up, check that the energy transfer uid is compatible
with the hydraulic circuit materials and coating. Where additives or
uids other than those recommended by the manufacturer are used,
ensure that these are not considered gases, and that they are
class 2, as dened in directive 2014/68/EU.
Manufacturer's recommendations concerning heat transfer
uids:
- No NH
4+
ammonium ions in the water as they 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 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
4
2-
sulphate ions can cause perforating corrosion, if their
content is above 30 mg/l.
- No uoride 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 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 qualied personnel using the air bleed
devices and tools and equipment suitable for the products.
The heat transfer uid should be lled and drained using
devices tted to the hydraulic circuit by the installer. Never
use the unit heat exchangers to add heat transfer uid.
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 dierent levels as possible,
Main points to be checked for the connection:
- Make sure that the stainless steel water lter is in the screen
lter. See gure 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-o 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 signicant static or dynamic pressure
into the heat exchange circuit (with regard to the design
operating pressures).
- The use of dierent metals in the hydraulic system may create
galvanic couples and lead to corrosion. Verify the need to
install sacricial 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 lter must be installed for units supplied without a
hydraulic module. This must be installed on the water inlet
pipe, upstream of the pressure dierential 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 lter must be no more than 1.2 mm.
If the lter is missing, the plate heat exchanger can quickly
become fouled during the rst 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 lter.
A lter with a mesh opening size of 0.8 mm must be installed at
the heat recovery option exchanger intake.
34
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