-18°F here (-28°C) here this winter. The heat pump (Mitsubishi) definitely worked hard and burned through our net-metering credit, but it did what we needed it

-18°F here (-28°C) here this winter. The heat pump (Mitsubishi) definitely worked hard and burned through our net-metering credit, but it did what we needed it to do. -15°C is just not even remotely a problem.