The ECS only decreases the temperature of the reactor, if you let water accumulate inside the reactor. If water is pumped in and straight out again, it is not heated and comes out at a few degrees over 15. Since this isn't described anywhere i guess this is a bug. Additionally, if you wire two pumps so that one activates when the reactor is empty, pumping the reactor full and one that activates if it is full, pumping it empty, the cooling provided is easily able to cool down even reactors running at 950° at 4 times neighbour boost, contrary to what the informatron entry says.

Yeah, cooling with the ECCS is a little whacky due to game mechanics. The heat exchange between water in the ECCS and the core happens each x ticks (forgot the exact number), and is depending on the amount of water in the tank. That means 2000 l of cold water cool more than 1000 l of already warm water. So when you change the water in the ECCS tank rapidly - which is totally possible with the vanilla pumps - you get that weird behavior.

I usually set one ECCS pump to "fill when core temp > 900" and another to "empty when ECCS water > 1500". Dont remember the exact numbers, but with something like that you will get to a more realistic cooling behavior.

Yeah, i use a memory cell setup now, where the imput pump is enabled at for example, 950° and runs until ECSS is over 4500. Then, the input pump is disabled and the output pump runs until the ECSS is under 500, after which both pumps are disabled until the temp hits 950° again.

But my main point was that this just isn't indicated in the informatron, etc. Almost caused me a meltdown or two... or four at once until i figured it out

well I just always push water to the reactor by a pump and only take the water inside the reactor out (with an another pump) at when above 975 C. but I use 2 tower per reactor. whenever I use only 1 tower per reactor with this, the reactor goes kaboom