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 exchanger water inlet and
outlet connections.
The piping must not transmit any axial or radial force to the
exchangers, or any vibrations.
The water supply must be analysed and appropriate filtering,
treatment, control devices, isolation and bleed valves and circuits
built in, to prevent corrosion, fouling and deterioration of the
pump fittings.
Before any start-up, make sure the heat-transfer fluid is
compatible with the water 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
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
-
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 1.0 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. 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 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).
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 water circuit by the
installer. The unit's exchangers must never be used
to top up the heat transfer fluid charge.
8.1 - Operating precautions and
recommendations
Before the system start-up verify that the water circuits are
connected to the appropriate heat exchangers.
The water circuit should be designed to have the least number
of elbows and horizontal pipe runs at different levels.
Main points to be checked for the connection:
-
Observe the water inlet and outlet connections shown 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 a pressure-reducing
valve and install a relief valve and an expansion vessel. Units
supplied with a hydronic 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).
-
If there are particles in the fluid which are liable to foul the
exchanger, a screen filter must be installed upstream of the
pump.
NOTE:
A screen filter must be installed for units supplied without
a hydronic module. This must be installed on the unit's water
inlet pipe, close to the unit heat exchanger. It must be located
somewhere easily accessible to enable disassembly and
cleaning.
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 hydronic module are equipped with this type of filter.
-
Do not introduce any excessive static or dynamic pressure
into the heat exchange circuit (with regard to the design
operating pressures).
-
Products used for thermal insulation of recipients during
hydraulic connection must be chemically neutral to the
surfaces on which they are applied. All original materials
supplied by the manufacturer comply with this requirement.
EN-31
AQUACIAT
POWER
ILD
