What should I do if the air source heat pump is frosted? How to solve the problem after frost

Defrosting failure means that the air source heat pump water condenser cannot defrost accurately when it is running in winter. There are many reasons. It may be that the unit itself cannot correctly determine the degree of frosting, cannot defrost in time, or "repeatedly" defrost when there is no frost; it may also be that the four-way reversing valve does not act properly when the unit executes the defrost command. If the defrosting power is too small, the "power" of the evaporator is offset by the heat loss, and the melted water cannot be discharged smoothly, causing large areas to freeze. These may make the heat pump incapable of working.

Ordinary air source heat pump products have inherent shortcomings in winter operation: from fin spacing, circulation design, controller's judgment of frost layer, system oil return and refrigerant liquid balance, there are defects in many aspects. For example, it is impossible for the controller to accurately judge whether the frost layer has formed and the severity of the frost layer only based on the evaporator temperature and cumulative operating time. The messy defrosting procedure cannot cope with different regions and different climatic conditions. Therefore, the defrosting effect of such an air source heat pump water device is relatively poor.

For maintenance personnel, what can be done is to clean the evaporator fins before the coming of winter to keep the fins good heat transfer capacity; according to the local climate settings, as far as possible in line with the local defrosting parameters (and for some continuous defrosting The settings of the air source heat pump water heaters that cannot be changed can be helpless); adjust the time controller, try to arrange the unit to work and store more hot water when the air temperature is high during the day; check and ensure the reliability of the auxiliary heating system Increase the daily inspection of the unit to prevent the outdoor unit from freezing; prevent the unit from increasing the possibility of frosting due to the shortage of refrigerant, and so on.

The air source heat pump has the unique advanced PID three-state defrosting method.

The three states mainly refer to three states: time, fin temperature, and ambient temperature.

PID refers to the proportional integral analysis of the above-mentioned three states, and the logic operation analysis of the change trend of the fins of the unit under different ambient temperatures in winter can be more accurately judged the frosting and defrosting of the unit.

For example, when operating at ambient temperature of -5°C, if you only judge based on the operating time and fin temperature, it will defrost without frost on the fins of the unit when the temperature is low. And through the three-state PID analysis of the change trend of the difference between the ambient temperature and the fin temperature, the frosting speed and severity of the fin surface of the unit can be correctly judged, so that when the frosting affects the energy efficiency of the unit When it is larger, it will enter defrosting. Normally, it will enter defrosting when the heating capacity of the unit drops to 75% of the initial heating capacity. The defrosting is also judged based on the rising speed of the fin temperature per unit time.

Listed as:

●When the defrosting time is 0-4 minutes and the fin temperature reaches 6℃, it can be judged that the unit has a good defrosting effect and can exit the defrosting;

●When the defrosting time is 4-6 minutes and the fin temperature reaches 8℃, it can be judged that the unit has a good defrosting effect and can exit the defrosting;

●When the defrosting time is 6-10 minutes and the fin temperature reaches 10℃, it can be judged that the unit has a good defrosting effect and can exit the defrosting;

●When the defrost time reaches 10 minutes, the unit will forcibly exit the defrost.

●In this way, it is possible to avoid the phenomenon that the exit temperature is a fixed value and cannot be exited immediately according to the defrost progress.

The three-state PID analysis defrosting method can not only completely defrost, but also achieve more energy saving.