I think this is more of a bug than an issue, hence I decided to post this here.
To start this off with, I'm using Development Build CL#TU-210489.
I was digging along this area with a large body of magma enclosed in neutronium and I wanted to convert some polluted water into steam as a purification method. Originally there was abyssalite surrounding some parts of the magma body.
The hole as shown below was filled with abyssalite before it was dug - the temperature of the abyssalite directly on top of the neutronium was around 30 degrees centigrade or so; however, once I removed the abyssalite, the air in contact with the neutronium started heating up immediately and very quickly - within a few seconds it had risen to the high-250 degrees C range. (Alleged bug #1)
Subsequently, I then decided to open up a small pocket of polluted water nearby and have it spill onto the neutronium. The polluted water was around 20 degrees C before it was transferred into the heating system.
As expected, the water started to vaporise, forming dirt and steam. However, the volumes of steam that came out were pathetically minuscule and the water quickly cooled down below it's original temperature as more water flowed in. (as illustrated above) (Alleged bug #2)
Steps to Reproduce
Have a pouch of magma enclosed in neutronium with an area surrounded with abyssalite - take note of the initial temperature of the abyssalite and the temperature of the air when the abyssalite is dug out. Have polluted water be dropped onto the neutronium that is on top of the magma - notice the change in temperature of the water after a while.
This issue has not been confirmed by a developer yet.