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一、types of maintenance and service for chiller systems
1、regular check and maintenance：
（1）schedule routine checks based on equipment operation and customer requirements;
（2）train the field operators of the equipment owner and explain practical technologies for chiller operation and maintenance;
（3）provide necessary value-added services;
（4）provide professional advices and improvement solutions for the chillers and auxiliary equipments.
2、preventative maintenance：
（1）preventative maintenance includes the aforementioned regular check and the followings;
（2）perform necessary preventative maintenance recommended by the manufacturer;
（3）clean the heat exchanger tubes and, if necessary, change refrigerant oil, oil strainers and filter driers, etc.
3、thorough maintenance：
（1) thorough maintenance includes regular check, value-added services and emergency troubleshooting;
（2）be responsible for troubleshooting and parts replacement if there is malfunction of the equipment.
4、emergency troubleshooting：
provide 24/7 emergency troubleshooting service supported by a developed service network system and well qualified service team for quick troubleshooting to ensure the shortest downtime.
5、energy-saving retrofit：
energy-saving retrofit refers to using variable frequency drive technology in the condenser water pumps and cooling fan motors to achieve energy saving and consumption reduction by regulating speed of water pumps and fan motors based on leaving chilled water temperature.
6、refrigerant oil analysis：
lubrication oil quality reflects the internal mechanical running status and trend. metal content, humidity and ph level of lubrication oil give key indexes to significant hidden malfunction of equipment. multistack’s professional oil analysis provides advices to eliminate dramatic hidden failures, avoid unexpected shutdowns and costly service fees, and protect your investments.
7、maintenance and retrofit of cooling tower, water pumps, fan coils and fresh air handling units.
二、maintenance and service details for chiller systems
1、chiller：
（1）check the high pressure and low pressure of refrigerant system;
（2）check for refrigerant leakage and if any, make replenishment;
（3）check the operating current of compressors;
（4）check the running noise of compressors;
（5）check the operating voltage of compressors;
（6）check the oil level and oil color of compressors;
（7）check the oil pressure and oil temperature of compressors;
（8）check the phase sequence relay for phase missing;
（9）check every terminal for loosen connection;
（10）check the operation of water flow switch;
（11）check the resistance of pcbs and temperature probes;
（12）check the air switch, a.c. contactors and thermal protectors.
2、air system：
（1）check the air volume of fan coils;
（2）check for accumulated dusts on the return air filter screen of fan coils;
（3）check air outlet temperature.
3、water system ：
（1）check condenser and chilled water quality;
（2）check strainers of condenser / chilled water system for foreign materials and clean the strainers;
（3）check whether there is entrapped air in the water system;
（4）check entering / leaving water temperature;
（5）check the sound and electric current of water pumps;
（6）check whether the valves are operating flexibly without rust and leakage;
（7）check insulation system for cracks, damages and leakage.
三、periodic follow-ups for chiller maintenance and service
（1）ask information from the engineering department about recent running conditions of the equipment and system;
（2）check the operation log of the equipment and system for malfunction;
四、chillers troubleshooting
1、normal operation check
（1）check oil pressure and oil volume of compressor refrigerant;
（2）carry out system (refrigerant) leak detection, find out leak point and repair in time;
（3）check for abnormal noise, vibration and high temperature;
（4）check the temperature and pressure of condenser and cooler;
（5）check the valves;
（6）check entering / leaving water temperature and pressure;
（7）check and tighten terminals on the main circuit;
（8）check the electric controls;
（9）check the oil system;
（10）check the working status of instruments and controller;
（11）keep clean of the equipments.
2、annual downtime check
（1）check and clean the filter drier, replace or dry the drying agent if necessary;
（2）check the set points of equipment controls;
（3）check oil pressure and oil volume of compressor refrigerant, change and supplement refrigerant oil if necessary;
（4）check insulation conditions of compressor motors;
（5）check and tighten contacts in the circuit;
（6）check electric controls;
（7）provide annual inspection report concerning checklist above. (once a year)
3、terminals check
（1）ahu and fan coil check (once a year);
（2）ahu and fan coil maintenance and oil replenishment (once a year);
（3）check and adjust the belt, clean the surface cooler and strainers (at least once a year);
（4）clean and descale pipelines (at least once a year);
（5）clean ahu and remove dusts (once a year).。
4、water system thorough check
（1）check the chilled and condenser water pumps and add oil;
（2）inspect the insulation of motor and electric fittings, add oil and, if necessary, replace sealing elements;
（3）carry out regular service and maintenance of cooling tower;
（4）check the valves, strainers, check valves, pressure gauges, temperature sensors and insulation conditions of critical parts in water system, and fix or replace faulty fitting(s), if any.。
5、cooling tower maintenance
（1）maintain, clean and change tower fills;
（2）maintain, clean, carry out anticorrosion treatment and, if necessary, change steel parts of cooling tower;
（3）maintain, clean, fix and change fiberglass parts of cooling tower;
（4）maintain, inspect and change cooling tower fans, motors and gear reducers;
（5）maintain and regulate static balance of cooling tower;
（6）maintain, overhaul and change water distributors and pipes of cooling tower;
（7）maintain, overhaul and change sprinkler heads and drift eliminators of cooling tower;
（8）maintain, clean and repair the tower basins and circulating water pipelines;
（9）remove cooling tower;
（10）repair and reconstruct cooling tower;
（11）upgrade thermal performance of cooling tower;
（12）repair the cooling tower when there is abnormal noise and vibration.
6、cooling tower maintenance considerations：
（1）appropriately adjust the v-belt of the blower type fan for it may loosen and extend slightly for the first run. do not make the belt too tight or it will damage the bearing.
（2）regularly clean the nozzles of distribution basin and the filter of collection basin;
（3）loosen and cover the belt if the cooling tower stops working for a long time. when resume operation, reinstall the belt, tighten the nuts and check whether there is nest or foreign materials in the cooling tower prior to the start-up.
（4）exchange circulating water at least once a month. in closed circuit, however, distributing water needs exchange instead of circulating water.
7、winterization considerations for cooling tower ：
（1）be sure to drain up circulating water and water stored in distributor when cooling tower is shut down for winterization.
（2）in closed circuit cooling tower, please open the circulating water outlet, air vent and drain valve of distribution water pump;
（3）use basin heater to prevent the collection basin from freezing in cold climates.
8、winterization considerations for closed circuit cooling tower：
（1）if a closed circuit cooling tower is required to operate in winter, antifreeze measures must be taken to protect the tubes (heat sink) and distributor;
（2）antifreeze solution should be added to the circulating water or electric heater be employed in tubing to prevent circulating water from freezing;
（3）with antifreeze solution, the freezing temperature of circulating water drops. the higher concentration of antifreeze solution, the lower freezing temperature it becomes. it should be noted that thermal conductivity will drop accordingly as well. so pay attention to water temperature since the makeup water used to compensate for the loss of water in leakage or normal loss will dilute the antifreeze solution and cause water freezing temperature to go up;
（4）electric heater is employed to prevent water from freezing during the operation of circulating water pump. an auxiliary pump is needed when the circulating water pump stops running. it is recommended to use the antifreeze package which includes the auxiliary pump, electric heater and piping;
（5）there is a 3-way valve in the circulating water system to control water flow. the increase of water flow in the 3-way valve will cause the water flow rate in the tube to slow down and may lead to freeze. please set the circulating water flow rate to the minimum value;
（6）there is a 3-way valve in the circulating water system to control water flow. the increase of water flow in the 3-way valve will cause the water flow rate in the tube to slow down and may lead to freeze. please set the circulating water flow rate to the minimum value.