Back draught shutter with external extractor fan

[wynkins]

Hi, I have an external centrifugal extractor in my kitchen, pulling directly through the wall via rigid 150mm ducting. There is a significant amount of draught, creating a cold spot in the kitchen. I need to fit a back draught shutter. My question is, whether a backdraught shutter will open when my external extractor tries to pull air through the closed shutter, rather than doing what an internal extractor does which is to push air through.
Many thanks

 

[Taylortwocities]

Of course it will. It is the same.

Think about the airflow direction, air entering from outside towards the inside will cause the shutter to close.