... pump + water tank CE;CCC;ISO9001. Working principle:Air-source Water Heater is also known as Heat-pump ... medium (cold medium) to collect heat from the air or the environment, heat up the cold water through ... work on cloudy, rainy, snowy days at night. Air-source Water Heater can work properly when the environmental ... more, it does not occupy any space in the open air, and easy to install, easy to use. The ...