This is our wonder heat pump high quality one. It can work in very low temperature environments. The Minimum operating temperature is -25 degrees Celsius . It adopts unique airflow design, making it quiet operation which design have patented. The wonder heat pump always maintain a higher heating capacity than traditional ON/OFF pool heat pump, providing you with a quality swimming experience . It uses R290 refrigerant, more efficient and energy-saving, and very environmentally friendly. It also has a simple control system for operation. R290 Gas Solution Unique Airflow Design Full Inverter Technology Ultra Silent Running High Efficiency Running Air Temp. -25°C~43°C Intelligent Defrosting Built-in Wi-Fi for Smart APP Control 2