I think it happens when you put an heat outlet down, surround it with heat vents and diagonally to one of the heat vents plave another heat outlet and then wait for a second.
I found a glitch. It happened twice when heat vents overfilled. The tick speed goes to ~20t/s and Things just keep losing durability, my heat goes into infinity and nothing happens. I get an infinite amount of power to collect, even when paused. When I break the vents everything overheats like normal.
Was this your first time playing? Try pausing and clicking on new, that should straighten things out, not sure why that occurred.