steam room mistery

As far as I can tell, the vent is overpressurized, so it can't inject more heat.

Then, you have low temperature steam in a room that is exchanging heat with the side walls (40C-65C), so it's normal that your steam will lose heat. Insulated tiles are not perfect insulators. A single layer is usually not enough to keep the heat in - some people would be better placed to explain the detailed mechanics and how thermal conductivity is calculated, but as far as I understand, it's better to have 2 layers of insulated tiles. In any case, the inner layer will heat up over time anyway, until it reaches equilibrium temperature with the steam room.

I ran your save a few cycles and the insulated tiles around the steam room are slowly heating up, as expected.

I don't see a bug here - You should either pump some of the steam out to allow the vent to release hotter steam, or heat the steam room until the turbines can do that themselves.

Edited August 13, 2023 by NeoDeusMachina