Water-cooled screw chiller provides 7-12℃ cold water in summer, and 50-55℃ hot water through heat exchanger in winter in urban heating network. Two circulating pumps are used for hot and cold water. In summer, start the chiller, hot and cold water circulating pump, cooling water pump and cooling tower fan to run the refrigeration cycle; In winter, start the plate heat exchanger and the hot and cold water circulating pump to run the heating cycle.
It should be noted that the unit should not be turned on and off frequently, and the air conditioner may be damaged due to frequent startup. When the unit is stopped for a long time, the coil and system should be filled with water to reduce the corrosion of the pipeline. However, when it is stopped for a long time in winter, all the water in the unit and system must be drained to prevent the coil and water supply pipeline from freezing and cracking. Be sure to control the running state of the air conditioning unit through the controller, and it is strictly forbidden to switch the unit by unplugging or plugging in the power supply.
First,Operating procedures for a summer refrigeration cycle:
1. Start and stop sequence of water chillers In order to ensure the normal operation of the air-conditioning main engine after starting, it is necessary to ensure that the condenser radiates heat well, otherwise the high-voltage protection device of the water chiller will stop because of the high condensation temperature and the corresponding condensation pressure, and even lead to failure.
The cold water in the evaporator should circulate, otherwise it will stop because the cold water temperature is low, which will lead to the action of the cold water temperature protection device, or stop because the evaporation temperature and the corresponding evaporation pressure are too low, which will even lead to the freezing of the cold water in the evaporator and damage the equipment.
The startup sequence of water chillers is: (strictly observed) Cooling tower fan on-cooling water pump on-cold water pump on-water chiller.
The shutdown sequence of water chillers is: (strictly observed) Chiller stop-cooling tower fan stop-cooling water pump stop-cold water pump stop.
2, the operation of the chiller
①the preparation work before starting:
1) Confirm that the power supply of the unit and controller is connected.
2) Confirm that the cooling tower fan, cooling water pump and cold water pump are all turned on.
3) Confirm that the fan coil units at the end have been powered on.
② Start. Press the status key ON the keyboard, and then switch the unit ON/OFF toggle switch under the keyboard to the ON position. The unit will conduct a self-inspection. After a few seconds, one compressor will start, and the other compressor will start after the load increases. Once the unit is started, all operations are not automatic. The unit automatically starts and stops according to the change of cooling load (chilled water supply and return water temperature).
③ Normal operation When the unit is running normally, the controller will monitor the oil pressure, motor current and other parameters of the system. In case of any problems, the control system will automatically take corresponding measures to protect the unit and display the fault information on the screen of the unit. There should be a special person to record the operating conditions of the unit at fixed intervals.
④ Shutdown. As long as the unit ON/OFF toggle switch under the keyboard is switched to the off position, the unit can be stopped. In order to prevent damage, don't cut off the power supply of the unit even when the unit stops.
3, fan, water pump operation The cooling tower fan, cooling water pump and cold water pump are all independently controlled. Before starting, make sure that the power supply is normal, and there is no reverse phase and no missing phase. Before starting the water pump, make sure that all the valves in the pipeline are open. Fans and pumps must be started and stopped in sequence.
Second, the winter heating cycle operation procedures:
Confirm that the pipeline valves of water chillers have been closed, the cooling tower fan and cooling water pump have been cut off, and the valves have been closed. Confirm that the main valve of the water inlet and return pipeline of the urban heating network has been opened, and the pipeline valve of the terminal heating system has been opened.
Check whether the power supply of the hot water circulating pump is normal, whether the valve is open and turn on the hot water circulating pump. Open the inlet and return pipe valves on both sides of the plate heat exchanger. When stopping heating, disconnect the power supply of the hot water circulating pump and close the main valve of the water inlet and return pipeline of the heating network.
Third, the maintenance of water chillers
1. Unit status: Press the status key on the keyboard to confirm that no fault information is displayed.
2. Refrigerant leakage: Visually check whether the heat exchanger, compressor and pipeline are damaged or leaked.
3. Working condition: Press the display key, read the working pressure and temperature from the control center, and check whether these values are within the operating limit given in the operation manual of the microcomputer control center.
4. Oil level: After the compressor runs at full load for about half an hour, check the oil level in the oil separator, which should be located between the upper and lower sight glasses of the oil separator.
5. Refrigerant charging: After the system is started or the energy level is changed, some bubbles can sometimes be seen in the sight glass. After a few minutes of stable operation, the bubbles will disappear, and all you can see from the sight glass is refrigerant liquid.
6. Oil heater: After the unit is shut down, the compressor oil heater will be turned on to prevent the refrigerant from condensing and dissolving into the lubricating oil, causing damage to the compressor. Don't cut off the power supply when it is stopped. If the main power supply must be cut off (for long-term maintenance or shutdown), the compressor suction, exhaust and motor cooling overhaul stop valves should also be closed (clockwise).
7. A qualified maintenance worker should be arranged. Generally speaking, "minor maintenance" should be conducted every three to six months, and "major maintenance" should be conducted once a year. In the process of maintenance, mainly pay attention to the following aspects:
1) The water filter installed outside the machine should be cleaned regularly to ensure the water quality in the system is clean, so as to avoid the damage of the unit caused by dirty filter plugging.
2) The surroundings of the unit should be kept clean and dry with good ventilation. If the air side heat exchanger can be cleaned regularly (for 1-2 months), it can maintain its good heat exchange effect and save energy.
3) Always check whether the water supply and exhaust devices of the water system work normally, so as to avoid air entering the system, which will reduce the water circulation and make it difficult, thus affecting the refrigeration effect of the unit and the working reliability of the unit.
4) Always check whether the wiring of the power supply and electrical system of the unit is firm and whether the electrical components are abnormal. In case of abnormality, it should be repaired and replaced immediately, and the unit should be reliably grounded.
5) Check the working conditions of various parts of the unit regularly, and check whether the working pressure of the refrigeration system of the unit is normal. Check whether there is oil pollution at the pipeline joint and charging valve in the machine to ensure that the refrigeration system of the unit has no leakage.
6) After an operation cycle, if the unit is shut down for a long time, the water in the pipeline of the unit should be discharged and the power supply should be cut off. Before starting the machine, the system should be filled with water and the unit should be fully inspected. After that, the unit should be electrified and preheated for more than 6 hours, and it can be started only after everything is confirmed to be normal.
Common faults and troubleshooting methods
| Fault phenomenon | cause analysis | Exclusion method |
| Exhaust pressure is too high |
1, the condenser water temperature is too high or insufficient flow.
2. There is air or noncondensable gas in the system.
3. The copper tube of condenser has serious scaling.
4. Too much refrigerant charge
5. The inlet valve of the condenser is not fully opened.
6, inspiratory pressure is higher than normal.
7, water pump failure |
1. Check the cooling tower, water filter and water valves.
2, discharged from the condenser
3, cleaning the copper tube
4, eliminate the excess
5, all open
6. Refer to the column "Excessive inspiratory pressure"
7, check the cooling water pump |
| Exhaust pressure is too low |
1, the water flow through the condenser is too large.
2, the condenser inlet water temperature is too low.
3. A large amount of liquid refrigerant enters the compressor.
4. Insufficient refrigerant filling
5, inspiratory pressure is lower than the standard. |
1. Turn down the valve
2, adjust the cooling tower fan speed or fan workbench number.
3. Check the expansion valve and its temperature sensing bulb.
4, filling to the specified amount
5. Refer to the column "Low inspiratory pressure" |
| Inspiratory pressure is too high |
1. Overfilling of refrigerant
2. At full load, a large amount of liquid refrigerant flows into the compressor. |
1, discharge excess
2. Check and adjust the expansion valve and its temperature sensing bulb to determine whether the temperature sensing bulb is fastened to the suction pipe and insulated; The inlet temperature of cold water is higher than the defined temperature. |
| Inspiratory pressure is too low |
1. The refrigerant liquid outlet valve of the condenser is not completely opened.
2. The refrigerant filter is blocked.
3. Improper adjustment or failure of expansion valve
4. Insufficient refrigerant filling
5. Excessive lubricating oil circulates in the refrigeration system.
6, evaporator inlet water temperature is too low.
7. The water passing through the evaporator is insufficient. |
1, all open
2. Replace the filter
3, correctly adjust the degree of superheat, check whether the bulb leaks.
4, added the specified value
5, find out the reason, reduce to a suitable value.
6, improve the inlet water temperature set point
7, check the water pump, water valve |
| Compressor shutdown due to high pressure protection |
1. The water passing through the condenser is insufficient.
2. The condenser copper tube is blocked.
3. Overfilling of refrigerant
4. The setting value of high voltage protection is incorrect. |
1. Check the cooling tower, water pump and water valve.
2, cleaning the copper tube
3, discharge excess quantity
4, the correct setting |
| The compressor stopped due to overload of the main motor |
1, the voltage is too high or too low and unbalanced
2, the exhaust pressure is too high
3, backwater temperature is too high
4. Overload original fault
5, the main motor or terminal block short circuit. |
1, find out the reason, make the voltage value and rating error within 10% or phase imbalance rate within 3%.
2. Refer to the column "Excessive exhaust pressure"
3. Find out the reason and eliminate it
4. Check the compressor current and compare the full current on the data.
5. Check the impedance between the motor terminal block and the ground wire and repair it. |
| Address : | No. 328 on the 4th plant hengyong Road, Jiading District, Shanghai |
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| Factory Address : | No. 328 on the 4th plant hengyong Road, Jiading District, Shanghai |
| Work Time : | 8:30-17:30(Beijing time) |
| Phone : |
86-021 -63184860-17(Work Time) 86--13916495206(Nonworking time) |
| Fax : | 86-021-53750132 |
| Email : | lucy@shkubao.com |
| Phone : | +86 13588563336 |
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| WhatsApp : | +86 13588563336 |
| Skype : | kub.mick |
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| Email : | kub02@shkubao.com |
| Phone : | +86 15001938306 |
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| WhatsApp : | +86 15001938306 |
| WeChat : | kub-maomao |
| Email : | kub@shhkubao.cn |
| Phone : | +86 15317830025 |
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| WhatsApp : | +86 15317830025 |
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| Email : | lucy@shkubao.com |