The operating boundaries of compressors significantly limit the operational envelope of air-to-water heat pumps, particularly in cold regions. The achievable supply temperature is constrained by the maximum refrigerant temperature \({T}_{2}\) in the compressor. Additionally, in these regions, the available heating capacity of heat pumps is. This hinders the widespread use of heat pumps in cold climates and uninsulated buildings with high heating demands. To enable comprehensive deployment of heat pumps, it is essential to identify measures that lower \({T}_{2}\) and increase heating capacity. High efficiency (COP) is also crucial for cost-effective operation. Previous studies have presented concepts for enlarging operational boundaries; however, there is a lack of simultaneous consideration of the three objectives— \({T}_{2}\) , heating capacity, and COP—under uniform boundary conditions. This study identifies promising measures for enlarging the operating envelope and compares them through simulations under uniform conditions. The focus is on quasi-two-stage compression concepts. Three quasi-two-stage refrigerant flowsheets—direct injection, with flash tank, and with economizer—are investigated using quasi-stationary refrigerant cycle simulations. R290 is used investigated as a promising refrigerant for residential heat pumps. The results show that the best compromise between efficiency and performance occurs in the refrigerant cycle with a flash tank: an \(18\%\) increase in efficiency and a \(53\%\) higher heating capacity while simultaneously lowering the maximum process temperature by \(18 K\) . Direct injection’s fewer additional components provide advantages such as broader operational ranges and reduced reliance on supplementary heaters compared to flash tank or economizer configurations, making it a potentially optimal solution in colder regions.