1. Check whether the outlet of the flue, that is, the inlet of the hood hose, has been changed from the front of the flue to the side during the transformation. Because the side width of the side auxiliary flue is only 100mm, which is much narrower than the big side. According to the aerodynamic principle, you change the air inlet to the position of the auxiliary flue, which reduces the rising speed of air discharge and increases the resistance of discharge. When there is convection between the air in your kitchen and the flue, the air pressure in the kitchen will be lower than that in the flue. Even if your range hood doesn't work, the same result will inevitably lead to smoke backflow. It must be changed back.

2. Check whether a check valve, also called flue connector, is installed. Conditional can buy backflow prevention check valve.

3. Whether the kitchen door or window is open. If the windows of your range hood don't open when working, air convection can't be formed, and the lampblack can't be discharged at all; When the range hood is not working, if you don't open the window, the air pressure in your kitchen will be less than that in the flue, and it is inevitable that the lampblack from other people's homes will flow back to your home.

4. Check whether the power of your range hood reaches 500m3/h, if not, please replace it in time.

5. Check whether the fume emission of the building where you live (according to the design regulations, the fume emission should be discharged separately) is received by the flue of the residential kitchen. If so, then I congratulate you, the oil fume will always flow back to your home. Because the power of the catering range hood is 2000m3/h, it is bigger and faster than your range hood, both in terms of emissions and discharge speed.

Secondly, do a few more things, which requires the cooperation of developers:

1. Check whether the smoke inlets of the upstairs and downstairs residents in your vertical range are open or not equipped with check valves, especially whether the smoke inlets of the upstairs residents are open. Failure to install a check valve will directly lead to the backflow of oil smoke downstairs.

2. Check whether your flue is a variable pressure flue (variable pressure flue can effectively prevent oil fume from flowing backward and stinking). According to the regulations of the Ministry of Construction, new buildings and newly designed houses must use variable pressure flue from 2006. If not, you can ask the developer to provide information on how the flue passed the acceptance and compensate you for your losses.

3. There are strict requirements in the design because the external cross-section dimensions of flue with different floors are different. Big or small, it will inevitably lead to the result of smoking. If there is a problem with the size, you can also compensate the developer.