Low ambient temperatures can have a negative effect on the overall efficiency and performance of a chiller heat pump. Pulling heat from colder air is difficult and requires more energy to produce the same amount of heating. Increased stress on compressors as well as frozen outdoor coils can shorten the overall lifespan of the heat pump chiller. Reduced capacity is also a challenge in low ambient temperatures as the refrigerant is less able to absorb heat from the ambient air.
These challenges may be addressed in a number of ways. Electric heaters or defrost systems may help prevent the freezing of outdoor coils and other equipment. Additionally, heat pump chillers can be used in conjunction with a boiler or used in a cascade system, which are both designed to help reduce the heating demands of the heat pump chiller.