The reason why the air source heat pump can absorb heat from the air is because the evaporation temperature of the refrigerant is much lower. When the refrigerant passes through the evaporator, it absorbs the heat in the air. When the evaporator temperature is lower than the dew point of the air, the surface of the evaporator will condense. If the ambient temperature is also close to or below 0 °C, it is easy to form frost on the surface of the evaporator. Of course, frosting has a lot to do with humidity. Under the same ambient temperature, the greater the humidity, the greater the possibility of frosting.
When the heat pump main unit is working, frost formation is normal. Generally, the manufacturer will design an automatic frost function according to the working environment to ensure the normal operation of the main machine. However, there will be some abnormal frosting, and most of the problems encountered by dealers at present are such cases.
Abnormal frosting is generally due to the insufficient amount of refrigerant passing through the evaporator, or the slower speed of passing, resulting in a low surface temperature of the evaporator, and the amount of refrigerant passing through is insufficient, either the refrigerant is insufficient or the evaporator is blocked. Of course, there are other factors, such as the temperature probe is broken, and so on.
What are the consequences of defrosting?
If the air source heat pump heating unit is not timely, the frost will become thicker and thicker, and there are three main effects:
The first one is that the hot water discharge capacity is greatly reduced. This is the most common problem for most dealers. The water temperature is not up to the design value or the heating rate is too slow. Even if the unit has been working continuously for more than 24 hours, the water temperature is still not reached. Claim. However, brands with good quality and reasonable design can achieve successful defrosting by increasing the heat exchange area, changing the defrosting settings reasonably, or increasing the anemometer to sacrifice heating sales.
In the second case, the evaporator of the unit is not frost, but ice. It may not produce hot water directly. If the defrosting design is unreasonable, the frost layer is not melted in one cycle, and the next cycle is started, so that the remaining frost layer quickly condenses with the new water to form ice.