Hi Thierry
I was unsatisfied with my ejector fan as well. I had to make some changes to it.
I narrowed down the air inlet slot by bending in tabs of the housing to increase the air velosity. Also, I added some hight to the tube.
My thinking was the increased air velosity would make for better draft by creating a more powerful underpressure. It worked so-so. I used the fan last winter like that and it pulled about twice the natural draft.
I decided to put some new silicone on the tab cracks this fall for no reason at all. The motor fried at first lightup. Well well, it’s been in use on top of the chimney for 10 years. I have a couple of more old fans somewhere, but for now I’m running natural draft only. Lightup is a bit slower but otherwise ok. This is two minutes after today’s lightup.
