the air source heat pump compressor

In the actual system design, also want to follow the rules of the heat pump running, give full play to the function of the special heat pump compressor. Specific attention should be paid to the following aspects:
 throttling device to ensure the wide range
Both fission and the integral heat pump water heater in the open air, the evaporation temperature are very wide. In order to effectively throttling in wide range, it is suggested that do not use single capillary, but USES the expansion valve or more groups of capillary. At the same time also to avoid the liquid directly into the compressor, especially in the winter.
the observation liquid strike, dip phenomenon, to assess risk
For static heating heat storage type heat pump water heater, the refrigerant migration is bypassing the problem: after the compressor stop working, in the condenser at a high temperature environment, compressor/evaporator cooling, temperature difference in cold media gradually migrate to the evaporator and the compressor.
Gathered at the refrigerant in the evaporator is likely to go into the compressor. That is to say, heat pump water heater in liquid impact degree is more serious than air conditioning. This phenomenon has been verified through many experiments. It is also a special heat pump compressor adopts accumulator design one of the reasons why the super capacity arc. 
Pay attention to the bottom of the compressor from the problem of heat
It is easy to be ignored during system design, but it is extremely important.The so-called heat at the bottom of the compressor, it is defined as: temperature, condensation temperature at the bottom of the compressor.If the value is zero or less than zero, compressor ontology has become a "condenser" at this time, cold media will slowly in compressed casing in condensed liquid and deposited at the bottom of the compressor, regarded as "lubricating oil" to the compressor pump body each sliding surface.Liquid refrigerant is no lubrication function.
Compressor running in winter, into the liquid refrigerant compressor internal quickly reduces the compressor body temperature. And heat pump water heater due to the need for making high temperature of hot water, the condensation temperature is higher. It is easy to occur at the bottom of the compressor temperature is lower than the phenomenon of condensation temperature. System experiments showed that when have a suction liquid occurs, in preparing 55 degrees, the more serious the environmental temperature is lower.
condensation side heat transfer set aside safety margin
No matter what type of heat pump water heater, after running for a long time, the water side of the heat transfer effect will decrease, heat transfer temperature difference will increase. So did you consider in the design the condensation side heat transfer temperature difference might happen in the future how to change, to set aside a safe margin, to ensure the safety of the compressor to run for a long time in scope.