When the bathroom ventilator is not working, will air flow back into the house from the exhaust port

If it is a two-way ventilation fan, there should be a one-way valve, which can be closed;

In the case of one-way ventilation fans, this is not the case. But there are still page valves.

Isn't the ventilation fan connected to an exhaust pipe with a diameter of 8 to 10 centimeters? When working, the indoor gas is pumped out of the pipe The most important thing is that there is a plastic cover at the end of the exhaust pipe There is a movable baffle that can rotate when the hood is blown up when the exhaust is blown out, and the gas is discharged Usually it is closed This can also prevent rats from getting into the room from the outside I guess your ventilation fan is not equipped with this kind of cover, so there is this question.

I don't think so, right.

First, you don't want to install that kind of wall-row exhaust fan, install ceiling-type.

Clause. Second, the exhaust fan must have the kind with that kind of valve.

Clause. 3. If possible, install an extra valve on the wall.

After these treatments, there will never be that kind of phenomenon again.

It depends on the air pressure inside and outside, and the air flows from the place with high air pressure to the place with low air pressure. How can you tell which side is bigger? According to the density of the air, the more people gather in life or where there are more exhaust gases, the density of the air in that place is greater than that around it.