What should I do if the air source heat pump evaporator is frosted, the water temperature is insufficient, or the unit shuts down?

When the heat exchanger of the air source heat pump is lower than the ambient temperature, condensation water will be generated on the surface of the heat exchanger. When the ambient temperature is below 0 degrees, the condensed water will frost, which will affect the performance of the heat exchanger in severe cases. Most air source heat pumps are equipped with automatic frost function. As long as the system is defrosted in time, further icing will not occur. Once defrosting is insufficient and ice forms, the water temperature will drop and the unit may even shut down. Below, the editor will tell you some common frost and icing treatment methods.

Air Source Heat Pump Manufacturer Production Workshop

1. Freezing at the bottom of the unit

Cause of the problem: The water flow in the water pan is not smooth.

Solution: Remove ice, clean up dirt, and keep the water outlet unblocked.

 

2. Partial freezing of evaporator

Cause of the problem: There is no frost at the defrost sensor and the defrost point is incorrect.

Solution: Manual forced defrost, and move the defrost sensor to the icing/frost area.

Ultra Low Temperature Inverter Air Source Heat Pump
Ultra Low-Temperature Inverter Air Source Heat Pump

3. The evaporator is full of frost/ice and does not defrost.

Cause of the problem: Defrost sensor, ambient temperature sensor failure, lack of fluorine, or system blockage.

Solution: Manual forced defrost, replace the sensor, or add fluorine according to the standard and weld it down to remove the blockage.

4. The defrosting is not clean and complete.

Cause of the problem: The temperature of the exit defrost coil is set too low or the position of the defrost coil probe is inappropriate.

Solution: Adjust defrost parameters and adjust defrost probe position.

Exposed fan coil custom Professional manufacturer using imported processing equipment
Exposed fan coil custom Professional manufacturer using imported processing equipment

5. Frequent frost in a short period

There are many reasons, such as the fin heat exchanger being clogged or blocked by foreign matter, the fan motor being damaged or the fan air volume configuration being too small, the refrigerant charge being too small, the throttle expansion valve opening is too small, the fin heat exchanger area is configured too much Wait a minute, give different solutions to different reasons.

 

6. The frost is very serious, and the fins are all covered with a thick layer of frost.

Cause of the problem: The temperature of the defrost coil is set too low, or the defrost time interval is set too long, resulting in the inability to enter the defrost action in time.

Solution: Adjust the defrost parameters, adjust the position of the defrost probe, and place it where the frost is most severe.

Exposed fan coil custom packing line
Exposed fan coil custom packing line

7. Frosting is uneven, with thick frost forming locally and no frost forming partially.

Cause of the problem: The refrigerant flow is uneven, some pipelines have a large flow rate, and some pipelines have a small flow rate.

Solution: The manufacturer is required to adjust the structure of the refrigerant distributor to match the flow rate with the evaporation capacity.

 

8. Low-pressure protection occurs during the defrost process.

Cause of the problem: The low-voltage detection during the defrost process is not delayed or the delay time is too short.

Solution: Low-voltage protection during the defrost process needs to be delayed or extended.

 

9. High-pressure protection occurs during the defrosting process

Cause of the problem: The temperature of the defrost coil is set too high, causing the high-pressure protection to still not exit the defrost.

Solution: Adjust the defrost parameters, lower the defrost exit temperature, and observe if the defrost is complete.

 

10. There is defrosting action even if the fins are not frosted.

Cause of the problem: The temperature (or temperature difference) entering the defrost coil is set too high, causing malfunction.

Solution: Adjust the defrost parameters, increase the entry defrost temperature (or temperature difference), and observe the frost on the fins to an appropriate degree before defrosting.

fan coil unit assembly line-yesncer
fan coil unit assembly line

It should be noted that it is normal for the evaporator of an air source heat pump to freeze when the ambient temperature is below 10°C. When the water temperature in the water tank is always over 30 degrees, and the host frequently defrosts and the temperature cannot rise, some supervisors recommend turning off the return water system first, and then rechecking the water temperature when the temperature rises. If the water temperature still cannot rise, it is only recommended to add auxiliary equipment. Heating equipment too.

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