Carrier 30HXC Installation, Operation And Maintenance Instructions

Also see for 30HXC Series: Installation, operation and maintenance instructions Installation, operation and maintenance instructions

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Carrier 30HXC Installation, Operation And Maintenance Instructions Manual pdf 36 page image

369 - WATER CONNECTIONSATTENTION: Before carrying out any water connections installthe water box purge plugs (one plug per water box in the lowersection - supplied in the control box).For size and position of the heat exchanger water inlet and outletconnections refer to the certified dimensional drawings suppliedwith the unit.The water pipes must not transmit any radial or axial force to theheat exchangers nor any vibration.The water supply must be analysed and appropriate filtering,treatment, control devices, isolation and bleed valves and circuitsbuilt in, to prevent corrosion, fouling and deterioration of thepump fittings. Consult either a water treatment specialist orappropriate literature on the subject.9.1 - Operating precautionsThe water circuit should be designed to have the least number ofelbows and horizontal pipe runs at different levels. Below themain points to be checked for the connection:• Comply with the water inlet and outlet connections shownon the unit.• Install manual or automatic air purge valves at all high pointsin the circuit(s).• Use an expansion device to maintain pressure in the circuit(s)and install a safety valve as well as an expansion tank.• Install thermometers in both the entering and leaving waterconnections.• Install drain connections at all low points to allow the wholecircuit to be drained.• Install stop valves, close to the entering and leaving waterconnections.• Use flexible connections to reduce the transmission ofvibrations.• Insulate all pipework, after testing for leaks, both to reduceheat gains and to prevent condensation.• Cover the insulation with a vapour barrier.• Where there are particles in the fluid that could foul the heatexchanger, a screen filter should be installed ahead of thepump. The mesh size of the filter must be 1.2 mm (see ‘Typicalwater circuit’ diagram).• The use of different metals on hydraulic piping could generateeletrolytic pairs and consequently corrosion. It could beneeded to add sacrificial anodes.Before the system start-up verify that the water circuits areconnected to the appropriate heat exchangers (e.g. no reversalbetween evaporator and condenser).Do not introduce any significant static or dynamic pressure intothe heat exchange circuit (with regard to the design operatingpressures).Before any start-up verify that the heat exchange fluid iscompatible with the materials and the water circuit coating.In case additives or other fluids than those recommended by Carrierare used, ensure that the fluids are not considered as a gas, and thatthey belong to class 2, as defined in directive 97/23/EC.Carrier recommendations on heat exchange fluids:1. No NH4+ ammonium ions in the water, they are very detrimentalfor copper. This is one of the most important factors for theoperating life of copper piping. A content of several tenthsof mg/l will badly corrode the copper over time.2. Cl- Chloride ions are detrimental for copper with a risk ofperforations by corrosion by puncture. If possible keep below125 mg/l.3. SO42- sulphate ions can cause perforating corrosion, if theircontent is above 30 mg/l.4. No fluoride ions (<0.1 mg/l).5. No Fe2+ and Fe3+ ions with non negligible levels of dissolvedoxygen must be present. Dissolved iron < 5 mg/l with dissolvedoxygen < 5 mg/l.6. Dissolved silicon: silicon is an acid element of water andcan also lead to corrosion risks. Content < 1 mg/l.7. Water hardness: > 0.5 mmol/l. Values between 1 and 2.5 canbe recommended. This will facilitate scale deposit that canlimit corrosion of copper. Values that are too high can causepiping blockage over time. A total alkalimetric titre (TAC)below 100 is desirable.8. Dissolved oxygen: Any sudden change in water oxygenationconditions must be avoided. It is as detrimental to deoxygenatethe water by mixing it with inert gas as it is to over-oxygenateit by mixing it with pure oxygen. The disturbance of theoxygenation conditions encourages destabilisation of copperhydroxides and enlargement of particles.9. Electric conductivity: 10-600μS/cm10. pH: Ideal case pH neutral at 20-25°C7 < pH < 8If the water circuit must be emptied for longer than one month,the complete circuit must be placed under nitrogen charge to avoidany risk of corrosion by differential aeration.Charging and removing heat exchange fluids should be done withdevices that must be included on the water circuit by the installer.Never use the unit heat exchangers to add heat exchange fluid.9.2 - Water connectionsThis diagram shows a typical water installation.Typical water circuit diagramLegend1 Control valve2 Air vent3 Flow switch for the evaporator4 Flexible connection5 Heat exchanger6 Pressure tap1 234 567891011127 Thermostat sleeve8 Drain9 Buffer tank10 Filter (mesh size: 1.2 mm = 20 mesh)11 Expansion tank12 Fill valve