The working fluid of heat pumps used to be Freon, but because Freon has a destructive effect on the earth's atmospheric ozone, in order to protect the earth's ecological environment, in addition to improving the refrigeration coefficient of the heat pump and effectively utilizing energy, various countries are also committed to the development of new working fluids. Working fluids that can replace Freon have been applied. However, the working fluid used by most manufacturers in China today is still R22, and the era of using environmentally friendly working fluids R417A and 134A has not yet come. Some countries, such as Japan, have taken the lead in using CO2 as a working fluid so as not to cause damage to the ozone layer. (So during installation, the copper pipes must be connected tightly to prevent R22 from leaking.) In addition, the above-mentioned R22, R417A, 134A, and CO2 do not cause harm to the human body. Even if there is leakage, the entire equipment is still safe. .