Heat pumps are often used as heat sources in new buildings. A heat pump is a system of different components that transfers heat from a low-temperature source to a high-temperature sink. This cycle is represented on the T-s diagram. To accomplish this the heat pump unit uses an external power supply and a specific working fluid. This working fluid is nowadays chosen with low GWP values. One example of a currently used low GWP fluid is R32. This refrigerant can give problems with the compressor superheat when used as a drop-in replacement for other refrigerants. High superheats are not allowed in the system, which limits the operational envelope of the heat pump. Therefore, a compressor with an injection line can be used to decrease the outlet temperature.