The fireplace is not burning well

Hello everyone,
First of all, thank you for your information.
We already had an expert in the house and he was not happy either when we described the problem.

I think we have to clarify this with the developer. I am eagerly awaiting his solution. A friend of ours also gave us a tip. We should put an inflated balloon into the vent. That way, no air could flow back.

I touched my head and said no thank you.
Best regards

Of course, I do not have extensive knowledge about this problem. However, I suspect it is due to the [raumluftabhängigen Betriebsweise]. I know this from a construction site where there was a similar problem. There, a 200mm KG pipe was installed outside.

In my house, I have a [raumluftunabhängigen Ofen], and here there are no differences due to wind or temperatures.
Best regards

Hello,
The way this fireplace is operated, it is extremely inefficient. An exhaust flap simply must be installed, along with a draft limiter. In my opinion, this can be done with the air supply via the rebate vents. The thing with the inflated balloon is, of course, nonsense.
Best regards

I simply assume that the two grates below have little to do with the combustion. The fire receives an air supply through the ash pan located beneath it. The firebox transfers the heat to the air via the grate. Thus, the fire remains the same, adjusting the grates does not help either.

Hello,
Under the door there is a slider. There is a symbol on it that looks like a volume control. I can also move it to the left and right. However, this has no effect on the fire in the fireplace. At least, that's how I perceive it. But I haven't adjusted anything on the grates.

However, I don't want to ask the chimney sweep, not that he shuts down our fireplace. Especially now that the cold season is beginning.
Best regards
Nina

Something about the controller. If the draft is high enough and you have no secondary regulation, you will not notice any change in the setting. This flap down there never seals tightly.

I see only three options with this problem. Either stop using the chimney, live with this situation, or retrofit the flap.

Best regards