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How to Properly Inspect and Maintain Ground Source Heat Pumps?

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How to Properly Inspect and Maintain Ground Source Heat Pumps?

Issue Time:2021-11-01
the correct inspection and maintenance methods of ground source heat pumps

Ground source heat pumps are popular with many consumers because of their better heat dissipation and heat storage functions. In daily life, you can use the following methods for inspection and maintenance, so as to keep the ground source heat pump clean, thereby extending its service life.

1. Visual inspection of the compressor

Inspection method: Visual inspection

Inspection standard: Check the reliability of the connection of the inlet and outlet valves of the compressor, and whether there is any leakage. During the test, attention should be paid to the operating sound of the compressor to determine whether there is an abnormality.

2. Voltage and current measurement

Measuring tools: Clamp-on ammeter with a clamp-on ammeter. Working voltage and operating current. The cable should be located in the center of the measurement loop when measuring the operating current.

Measurement standard: The operating voltage range is 380V (±10%), and the operating current should not be greater than the rated input current on the motor nameplate.

3. Measurement of insulation resistance

Measuring tool: Megohmmeter

Measurement method: With the unit cut off the power supply, use a megger to check whether the three-phase ground resistance of the compressor meets the standard. If the unit has not been activated for a long time, the crankcase of the unit should be electrically heated first to heat the oil cavity of the unit to evaporate the freon in the unit oil and improve the accuracy of the resistance measurement. To prevent the insulation layer from being broken down and causing accidents.

Measurement standard: The insulation standard of the compressor motor is not less than 500 megohms, the actual measured value should be greater than 100 megohms to be qualified, and the insulation value in the hot and cold state is greater than 8 megohms before.

4. Determination of oil

Measurement method: A small amount of refrigerating oil can be extracted from the unit and put into the container, and one drop can be put into the acid reagent bottle to observe the acidity, and compare it with the colorimetric chart. If the refrigerating oil meets the comparison color of the colorimetric chart, there is no need to change the refrigerating oil.

A small amount of refrigerating oil can be extracted from the unit and put into the container to minimize the exposure time in the air, and then use the PH test paper to judge the acidity of the oil. Those that meet the oil acidity requirements do not need to replace the refrigerating oil. Use absorbent paper to check the impurities in the oil. If there is carbon precipitation or other impurities, the refrigerating oil should be replaced.

Maintenance tools: Pipeline cleaning machine or chemical cleaning agent

Maintenance method: The condenser of the water-cooled unit uses a shell-and-tube water-cooled condenser. The cleaning and maintenance of the condenser are very important. The cooling water quality should be kept in good condition.

The cooling water should be chemically treated regularly to ensure that there is no scaling in the heat transfer tube.

Mechanical cleaning method

(1) Close the cooling water inlet and outlet valves;

(2) Disassemble the front and rear cover of the condenser;

(3) Clean the scale and rust in the condenser end cover and the water chamber cavity;

(4)Use a pipe cleaner to clean the heat transfer pipe; 

(5) After cleaning, rinse with clean water until it reaches the standard, and then cover the end cap.

Maintenance standards: After maintenance, the water chamber and heat transfer tube are visually clean as a whole, and there is no obvious scaling on the tube wall

Precautions

(1) The method of cleaning should be determined according to the form of the condenser heat exchange tube;

(2) The chemical cleaning agent must be uniform;

(3) The concentration and cleaning time of the cleaning agent should be carried out in accordance with the manufacturer's instructions;

(4) When rinsing with clean water, it must be clean and there should be no residue.
 
5. Inspection of the expansion valve

Inspection tool: Surface contact thermometer

Inspection method: Check whether there are oil traces at the connection of the expansion valve determine whether the expansion valve opening is appropriate during operation according to the superheat of the unit and the degree of condensation at the return end of the compressor.

Check whether the binding position of the temperature sensor is loose and the temperature sensor Whether the capillary tube is worn or not. Protect the balance pipe connecting nuts and valve body bolts against rust.

6. Inspection of sight glass and replacement of filter drier

Inspection tool: Surface contact thermometer

Inspection method: Visually inspect the display of the test paper in the sight glass to determine the dry humidity of the system refrigerant, confirm whether the dry filter element needs to be replaced, and measure the temperature difference between the front and rear of the filter with a surface contact thermometer. If the temperature is lower than 0.5 ℃, the filter is clean.

How to replace the filter drier

(1) First close the outlet angle valve of the high-pressure accumulator, turn on the engine unit and suck the refrigerant on the low-pressure side of the system (it is strictly forbidden to pump it to a vacuum state), and then lock the unit;

(2) Check whether the pressure on the side of the filter drier is lower than 2.0kg/c㎡, if so, connect the refrigerant pipe to discharge the gaseous refrigerant at this part;

(3) Loosen the screws of the end cap of the filter drier diagonally (pay attention to the temperature difference before loosening to prevent the temperature difference and water from being brought into the system).

Replace the old filter element after emptying the refrigerant, and wipe the dry filter cylinder quickly. Inside, replace the filter element with a little bit of refrigerating oil to seal the cylinder port;

(4) After vacuuming, add a little refrigerant, open the valve that was closed in the front. Maintenance standard: The sight glass indicates that it is in the drying zone, and the temperature difference before and after the dryer is less than 0.5°C.

7. Maintenance of electrical components

Testing tools: multimeter and clamp ammeter

Maintenance methods

(1) Check and tighten the wiring terminals on the electrical circuit, and check the burning condition of the contacts of each contactor;

(2) Polish the contacts with canvas to remove oxides. If the burn is severe, it is recommended to replace it;

(3) Check whether the solenoid valves, such as the four-way reversing valve solenoid valve, the unit loading and unloading solenoid valve, the liquid injection solenoid valve, and the electric heating are normal.

8. Check each safety device

Maintenance method: Check and test each safety device (thermal protector, flow switch, high voltage switch, etc. various protection devices), check the setting parameters.

Maintenance standard: The thermal protection is well fixed, the wiring is intact, the flow switch is oiled, the opening and closing action are normal, and the high and low-pressure switch action is 24.5±0.5Bar.

For ground source heat pump maintenance, it is best to find professional ground source heat pump maintenance personnel to carry out. As an expert who has studied heat pump systems for many years, SUOHER can provide you with more professional advice.

As a heat pump manufacturer, we have accumulated rich design and production experience in this field. We have a complete quality management system and strict quality inspection department, which can control the quality of our products in an all-round way. At the same time, we will provide thoughtful one-stop service and effective solution technology according to the actual needs of customers. If you want to buy our air source heat pump or learn about related services, please contact us immediately!
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