tweake:

 

while most will put out a puff of smoke when opening doors etc, its should not be puffing out smoke due to wind. back drafting is often caused by insufficient draw by the chimney (blockage, not enough height, poor location etc). it also can be made worse by using a badly installed heat transfer system. ie your pulling air out of the room and creating a low pressure area which makes it more likely for the fireplace to back draft.

 

btw there is also fully sealed ones with external air inlet (i have also found fake versions of them).