27
ATTENTION: Charging, adding or draining fluid from the
water circuit must be done by qualified personnel, using air
vents and materials suitable for the products. Water circuit
charging devices are field-supplied. 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.
12.1 - Operating precautions and recommendations
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.
•
Use a pressure reducer to maintain pressure in the
circuit(s) and install a safety valve as well as an expan-
sion tank. Units with the hydronic module include a
safety valve and 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 vibration transmission.
•
Insulate all pipework, after testing for leaks, both to
reduce thermal leaks and to prevent condensation.
•
Wrap the insulations with a demisting screen.
•
If the external unit water pipes are in an area where
the ambient temperature is likely to fall below 0°C,
they must be protected against frost (frost protection
solution or electric heaters).
NOTE: for units not equipped with a hydronic module a
screen filter must be installed. This must be installed on the
water entering pipes upstream of the pressure gauge and
close to the unit heat exchanger. It must be located in a
position that is easily accessible for removal and cleaning.
The mesh size of the filter must be 1.2 mm.
The plate heat exchanger can foul up quickly at the initial
unit start-up, as it complements the filter function, and
the unit operation will be impaired (reduced water flow
rate due to increased pressure drop).
Units with hydronic module are equipped with this type
of filter.
Do not introduce any significant static or dynamic pressure
into the heat exchange circuit (with regard to the design
operating pressures).
The products that may be added for thermal insulation of
the containers during the water piping connection proce-
dure must be chemically neutral in relation to the materials
and coatings to which they are applied. This is also the
case for the products originally supplied by Carrier.
12 - WaTER CONNECTIONS
For size and position of the unit water inlet and outlet
con-nections 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
filter-ing, treatment, control devices, shut-off and bleed
valves and circuits built in, to prevent corrosion (example:
damage to the protection of the tube surface if the fluid is
polluted), fouling and deterioration of the pump fittings.
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
direc-tive 97/23/EC.
The pumps in the hydronic module are compatible with
40% propylene glycol and 40% ethylene glycol. But if
these fluids are used, the pump fittings need to be replaced
more frequently (every 15000 operating hours instead of
25000 hours for an appliacation using water).
Carrier recommendations on heat exchange fluids:
•
No NH
4+
ammonium ions in the water, they are very
detrimental for copper. This is one of the most impor-
tant 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 detrimental for copper with a risk
of perforations by corrosion by puncture. If possible
keep 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
dis-solved 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 < 1mg/l.
•
Water hardness: >0.5 mmol/l. Values between 1 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 oxyge-
nation 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.
•
Electric conductivity: 0.001-0.06 S/m (10-600 µS/cm).
•
pH: Ideal case pH neutral at 20-25°C (7 < pH < 8).
Summary of Contents for 30RQ 039 Series
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