I grew up in a house with a fireplace, my father taught me how to make a fire and properly use the fireplace. I built fires in other people's homes (in their fireplaces, not in the middle of their bedroom or anything


I have seen it in various places, so it seems quite commonplace here. I've only seen fireplaces with at best 1 handle, to open/close the chimney. But 2?
Can someone please educate me on those handles so I can safely uses fireplaces here in Finland and not burn down the place or kill people with carbon monoxide poisoning or something?

The best I've come up with so far is that the top one is to open/close the chimney. So it should be open while using the fireplace. And the bottom one seems to flip a sort of lid which makes the heated air flow around the soap stones, heating them more before the air exits around via another way into the chimney.
I may be horribly wrong, I've never used such a fireplace before. I tried to find information online but I can't even find a picture of a fireplace with 2 handles, let alone a video about it on youtube (honestly I tried
