Carrier Aquasnap 30RW Installation, Operation And Maintenance Instructions

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Carrier Aquasnap 30RW Installation, Operation And Maintenance Instructions Manual pdf 38 page image

3815.2 - general unit maintenance• Keep the unit itself and the space around it clean andfree of obstructions. Remove all rubbish such as packingmaterials, as soon as the installation is completed.• Regularly clean the exposed pipework to remove alldust and dirt. This makes detection of water leakseasier, and they can be repaired before more seriousfaults develop.• Confirm that all screwed and bolted connections andjoints are secure.• Secure connections prevent leaks and vibration fromdeveloping.• Check that all foam insulation joints on the heatexchanger piping are in good condition.15.3 - Refrigerant charge15.3.1 - UnderchargeIf there is not enough refrigerant in the system, this isindicated by gas bubbles in the moisture sight glass.If the undercharge is significant, large bubbles appear inthe moisture sight glass, and the suction pressure drops.The compressor suction superheat is also high. The machinemust be recharged after the leak has been repaired.Find the leak and completely drain the system with arefrigerant recovery unit. Carry out the repair, leak testand then recharge the system.IMPORTANT: After the leak has been repaired, the circuitmust be tested, without exceeding the maximum low-sideoperating pressure shown on the unit name plate.The refrigerant must always be recharged in the liquid phaseinto the liquid line. The refrigerant cylinder must alwayscontain at least 10% of its initial charge. For the refrigerantquantity per circuit, refer to the data on the unit name plate.15.3.2 - Verification of the chargeCAUTION: The 30RW units are supplied with a preciserefrigerant charge (see Physical Data table).To verify the correct system charge prodeed as follows:Ensure that no bubbles appear in the sight-glass, whenope-rating the unit at full load for a while. Use a saturatedcon-densing temperature between 45 and 50°C. Underthese conditions the apparent subcooling which is equal tothe saturated condensing temperature (1 - on the saturateddew point curve) minus the liquid refrigerant temperature(3) ahead of the expansion device must be between 12 and14°C. This corresponds to an actual subcooling temperatureof between 6 and 8 K at the condenser outlet, depending onthe unit type. Actual subcooling is equal the saturatedliquid temperature (2 - on the saturated bubble point curve)minus the liquid refrigerant temperature (3) ahead of theexpansion device. Use the pressure tap supplied on the liquidpiping to charge refrigerant and to find out the pressure ofthe liquid refrigerant. If the subcooling value is not correct,i.e. lower than the specified values, a leak detection test mustbe carried out on the unit, as it no longer contains its originalcharge.WARNINg: To ensure proper operation of 30RW unitsthere must be at least 12 K of subcooling as the liquidrefrigerant enters the expansion valve.The 30RW units use refrigerant. For your information, weare reproducing here some extracts from the officialpubli-cation dealing with the design, installation,operation and maintenance of air conditioning andrefrigeration systems and the training of people involvedin these activities, agreed by the air conditioning andrefrigeration industry.Apparent and actual subcoolingPressureEnthalpylegend1 Saturated condensing temperature at the dew point2 Saturated liquid temperature at the bubble point3 Liquid refrigerant temperature4 Saturation curve at the dew point5 Saturation curbe at the bubble point6 Isotherms7 Apparent subcooling (1 - 3)8 Real subcooling (2 - 3)L LiquidL + V Liquid + vapourV Vapour15.4 - Refrigerant guidelinesRefrigeration installations must be inspected and maintainedregularly and rigorously by specialists. Their activities mustbe overseen and checked by properly trained people. Tominimise discharge to the atmosphere, refrigerants andlubricating oil must be transferred using methods whichreduce leaks and losses to a minimum.• Leaks must be repaired immediately.• If the residual pressure is too low to make the transferalone, a purpose-built refrigerant recovery unit mustbe used.• Compressor lubricating oil contains refrigerant. Anyoil drained from a system during maintenance musttherefore be handled and stored accordingly.• Refrigerant under pressure must never be dischargedto the atmosphere.345162LL + VV