PneumaticCraft adds a whole heat system. It behaves similar to how heat spreads in real-life. It has some similarities with how pressure disperses too:

-Heat will disperse from hotter objects to colder objects.
-Blocks will only spread heat to adjacent blocks that work with heat.
-The bigger the temperature difference, the faster the spread.
-Different objects have a different thermal resistance. Torches and Air have a high resistance, where machines like a Plastic Mixer have a very low heat resistance. This determines how fast heat can spread from one object to another.
-Different objects have a different thermal capacity. The higher the capacity, the slower the temperature will rise for the given heat. Similarly, the slower the temperature will drop for the given heat loss.

Liquids are static in terms of temperature. They will change when having drained/deposited a certain amount of heat to them:
-Fluids with a temperature equal or higher than Lava will turn into Obsidian when too much heat is exhausted out of it.
-Fluids with a lower temperature than lava will turn into Stone when too much heat is absorbed, and will turn into Ice when too much heat is exhausted.

Static heat sources are:
-Air
-Ice
-Packed Ice
-Snow
-Torch
-Fire
-Any Liquid (including Water and Lava)

Dynamic heat sources, used to control heat:
-[link{block/vortexTube}]Vortex Tube[link{}]
-[link{block/compressedIronBlock}]Block of Compressed Iron[link{}]
-[link{block/heatSink}]Heat Sink[link{}]

[prefix{l}]Heating a Furnace[prefix{}]
When connecting a Furnace to any dynamic heat source (mentioned above, but also blocks like Compressors that produce heat), the heat will be used by the Furnace to fuel it. Additionally the Furnace will smelt faster the higher the temperature. This effect can be stacked with multiple heat sources around the Furnace. This furnace fueling will start to work at 100 degrees C.

[prefix{l}]Heat Frame[prefix{}]
A [link{item/heatFrame}]Heat Frame[link{}] is an item that can be used to heat (or freeze) items in any inventory. For more info visit the relevant page.