Why does the air-energy heat pump emit white smoke after frosting in winter?

The air-energy heat pump emits white smoke, which is the phenomenon of machine defrosting after frosting. So why does frosting occur?

Why does the air-energy heat pump unit frost?

The air-energy heat pump unit frosts in winter, that is, when the unit is heating, the outdoor temperature is usually below ten degrees when the heating mode is started. When the outdoor temperature is low and the outdoor unit still needs to absorb heat, the temperature of the evaporator body will drop below 0 degrees, and the moisture in the surrounding air (similar to dehumidification during refrigeration) will quickly condense into frost. The amount of frost is related to the surrounding air humidity. Generally speaking, the higher the air humidity, the more frost there will be. On the contrary, the drier the weather, the less frost there will be.

There are two types of frost here: frost during normal operation, and malfunction during machine defrosting.

After frosting during normal operation, the air-energy heat pump itself has an automatic defrost function. The unit determines whether to defrost by detecting the temperature of the evaporator coil. There are two general defrosting methods: 1. Passive defrosting, 2. Automatic defrosting.
The so-called passive defrosting means that the unit is shut down and the external ambient temperature is defrosted. This method is generally suitable for areas where the ambient temperature is above zero degrees, and the defrosting time is long, which affects the use effect.
Automatic defrosting is when the unit uses the switching of the four-way valve to change the position of the evaporator and condenser, and uses the system heat to defrost. This defrosting method will cause the water temperature to fluctuate rapidly, but the defrosting is fast and the effect is good. Now the air energy adopts this defrosting method.
During automatic defrosting, the fan will stop first, the four-way valve will be reversed, and the functions of the evaporator and condenser will be interchanged. At this time, the water temperature will drop, the frost will continue to melt, the evaporator will emit white smoke, and the water will flow down. After the frost is removed, the fan will start and the four-way valve will be reset. At this time, a larger white smoke will be seen blowing out of the unit, and then the unit will restart heating, and the defrosting will end.
This is a phenomenon during defrosting. Many users do not understand why the unit smokes and leaks water continuously, so they think that the unit is faulty or on fire. This is a normal phenomenon during the normal operation of the unit.

In addition to normal defrosting, there is another situation where the machine defrosts and fails. So when the machine cannot defrost normally, what should be done?
1. What should I do if the evaporator is partially frozen?
The reason for the evaporator to freeze may be that there is no frost at the defrost sensor and the defrost point is inaccurate. The solution is to manually force defrost and move the defrost sensor to the frosted place.
2. What should I do if the evaporator does not defrost?
There are three possibilities. One is that the defrost sensor and the ambient temperature sensor are faulty, and the sensor needs to be replaced to solve the problem; the second is that there is a lack of fluorine or the system is blocked. It is necessary to add fluorine according to the standard and clean the system; the third is that the four-way valve does not reverse, see if the valve is powered on and whether it is operating normally.
3. What should I do if the defrost is not clean?
The problem may be caused by the temperature setting of the exit defrost coil being too low, resulting in unclean defrosting. At this time, you need to adjust the defrost parameters and observe patiently until the defrost is over. It may also be that the sensor probe is not placed in the most severe frosting place. In this case, just move the probe.
4. What should I do if all the fins are frosted?
It may be that the temperature of the defrost coil is set too low, or the defrost time interval is set too long, and the defrost action cannot be entered in time. You need to adjust the defrost parameters, increase the temperature of the defrost coil, and shorten the defrost time interval.
5. What should I do if frosting occurs frequently in a short period?
The fin heat exchanger is blocked, the fan motor is damaged, or the fan air volume is too small. The solution is to clean the heat exchanger and repair and replace the motor.