22
7 - WATER CONNECTIONS
ATTENTION: Before carrying out any water connections
install the water box drain plugs (one plug per water box
in the lower section - supplied in the control box).
For dimensions and position of the water inlet and outlet
connections refer to the certified dimensional drawings
supplied with the unit. The water pipes must not transmit
any radial or axial force to the heat exchangers nor any
vibration.
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.
Carrier recommendations on heat exchange fluids:
1. 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.
2. Cl
-
Chloride ions are detrimental for copper with a risk
of perforations by corrosion by puncture. If possible
keep below 125 mg/l.
3. SO
4
2-
sulphate ions can cause perforating corrosion, if
their content is above 30 mg/l.
4.
No fluoride ions (<0.1 mg/l).
5. 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.
6. Dissolved silicon: silicon is an acid element of water and
can also lead to corrosion risks. Content < 1 mg/l.
7. Water hardness: > 0.5 mmol/l. Values between 1 and 2.5
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.
8. Dissolved oxygen: Any sudden change in water
oxygenation 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 encourages destabilisation of copper
hydroxides and enlargement of particles.
9. Electric conductivity 10-600μS/cm.
10. pH: Ideal case of neutral pH at 20-25 °C
(7.5 < pH < 9).
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.
CAUTION: Filling, completing and draining the water
circuit charge must be done by qualified personnel, using
the air purges and materials that are suitable for the
products.
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.
7.1 - Operating precautions
The water circuit should be designed to have the least number
of elbows and horizontal pipe runs at different levels. Below
the main points to be checked for the connection:
•
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(s).
•
Use a pressure reducer to maintain pressure in the
circuit(s) and install a relief valve as well as an expansion
tank.
•
Units supplied with hydronic module include a chilled
circuit relief valve. Units supplied with option 293
include an expansion tank.
•
Install thermometers in both the entering and leaving
water connections.
•
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, both to
reduce heat gains and to prevent condensation.
•
Cover the insulation with a vapour barrier.
•
Where there are particles in the fluid that could foul the
heat exchanger, a screen filter should be installed ahead
of the pump. The mesh size of the filter must be 1.2 mm
(see ‘Typical water circuit diagram’).
•
Before the system start-up verify that the water circuits
are connected to the appropriate heat exchangers (e.g.
no reversal between evaporator and condenser).
•
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 recommended
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 2014/68/EU.
Summary of Contents for AquaForce 30XAV 1050
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