How to solve the problem of cool air after the exhaust fan in the kitchen of North Hotel stopped?

The nozzle is equipped with a rotator. The cold air treatment method in the kitchen after the range hood is stopped is to install a runner at the nozzle, which will turn on the runner when the pumping unit is working and turn automatically when it is not working, so that the winter wind will not enter from the range hood. The range hood is a kind of machine that can quickly exhaust the peculiar smell, high temperature and oil fume gas produced in the process of kitchen food processing. The machine is characterized by good high temperature resistance and high efficiency.