Problem solved! Today I replaced all the hoses again with new ones and also made sure that the water flows through the miner without any blockages. Then I filled it back up with demineralized water and paid special attention to proper venting. I also positioned the radiator higher and lowered the miner a bit.

In the meantime, I’ve also figured out what I was doing wrong. The mistake was filling the water reservoir to the brim during operation and then tightening the top screw extra tightly as well. That effectively created a closed loop and left too little space for the heat to expand. (That’s why heating systems use expansion tanks.)

I learned a lot this weekend!

One final word: Don’t mess around with electricity. I had all the electrical connections installed properly by a qualified electrician. Under the system I installed a ramp so that water can drain off immediately. In case of a malfunction - 1st thing: Power off!