The problem is the entire thing. That's a torch, not a burner and there is a huge difference. That little torch will never be able to heat up much brick and until the brick is hot the steel won't get hot.
A better approach is to build your own simple burner, build a simple forge body using Kaowool or some similar product, and feed the whole thing with propane. Propane comes in larger 20 lbs bottles of the type you usually find on BBQ pits. I know you are in Germany but I'm hoping you have propane bottles and BBQ pits over there.
I have a DVD that details the steps in building a simple burner and forge body, it runs about 90 minutes. In the video I build two different burners and a forge body start to finish and then demonstrate how it works. The video is $12 US shipping included. You can also get it off Amazon for a few dollars more but that might be easier for you. Look for it under Knife Making for Noobs Forge Building. You really need it ....