Heat Management
The mid-game heat wall, why it filters players, and how to manage it. Insulation, passive sinks, and the Thermo Aquatuner plus Steam Turbine loop.
Heat is the crisis that decides whether a colony lives past the mid game. Oxygen and food are problems you can brute-force, but heat is different: heat energy is conserved and genuinely hard to destroy, so in a sealed base it accumulates until crops die, machines break, and dupes overheat. The community calls the moment this comes due the heat wall, and it is the point that filters players. This page covers where the heat comes from, why it is so hard to remove, and the ladder of fixes from cheap insulation up to active cooling. Get ahead of it early, because heat is far easier to prevent than to delete.
Where the heat comes from
Almost everything you build to survive also makes heat. Generators dump it, refineries dump it, and electrolyzers hand you hot oxygen and hydrogen (reported around 70 C or above straight out of the SPOM). On top of your own machines, the map fights you: magma sits at the bottom of many asteroids, hot geysers vent scalding fluids, and the Oily biome is hot enough to scald dupes. All of that heat has to go somewhere, and in a sealed base there is nowhere for it to go on its own.
Why heat is hard to delete
Heat moves by conduction between touching materials, and the transfer speed is set by the lower conductivity of the two. That single rule is the whole game of heat management. Insulated Tiles and pipes have very low conductivity, so heat crawls through them. Abyssalite, the material that separates biomes, is a near-perfect insulator. You use these facts in both directions: to keep the cold of a chilled base in, and to keep the heat of a hot biome out. What you cannot do is make heat vanish by moving it around. Moving it only relocates the problem. Real deletion needs a specific machine, which is why the aquatuner loop exists.
The overheat threshold
Most buildings overheat at 75 C and take damage above that, but the build material raises the ceiling. This is a lever you control at construction time.
| Material | Overheat bonus |
|---|---|
| Granite, Igneous, Obsidian | plus 15 C |
| Copper, Gold, Iron, Tungsten | plus 50 C |
| Steel | plus 200 C |
| Ceramic, Diamond | plus 200 C |
Some buildings ignore the default entirely. An Oil Well tolerates around 2000 C, while the Thermo Aquatuner, Space Heater, and Liquid Tepidizer sit around 125 C, and the Steam Turbine stops at 100 C and takes damage near 1000 C. Building your hot machines out of Gold Amalgam or Steel is often the difference between a working setup and a smoking ruin.
The heat wall does not announce itself. It arrives as wilting crops and overheating machines around the same time your generators and electrolyzers hit full tilt. If you wait for the symptoms to plan cooling, you are already behind. Insulate the perimeter and build heat-tolerant early.
The ladder of fixes
Cooling is a ladder, and you climb it as your heat load grows. Start with the cheapest option that keeps up, and move up only when it stops keeping up.
First, insulate. An insulated base perimeter and Abyssalite barriers keep hot biomes from bleeding into your living space, and this alone buys many cycles. Second, use passive sinks: Wheezeworts are passive gas coolers that work best in hydrogen, and the Tundra biome’s Anti Entropy Thermo-Nullifier deletes heat using hydrogen. Ice and cold biome resources give a one-time cold dump for early spikes. Third, when passive cooling can no longer keep up, build the active loop.
The active answer is the Thermo Aquatuner plus Steam Turbine combo. The aquatuner cools a liquid coolant but dumps a lot of heat and draws heavy power, so it sits inside a sealed steam chamber where the dumped heat boils water into steam, and a Steam Turbine on top converts that steam heat back into power while returning cooled water. This is the one setup that genuinely deletes heat and recovers part of it. Coolant choice matters: Polluted Water is the preferred cheap option for its lower freeze point and fewer burst pipes, while Super Coolant (made from Petroleum) is far more efficient and lets a tuned loop run close to energy neutral. The cooling loops cheatsheet has the inputs and outputs on one page.
The permanent tax
By the late game, cooling is not a project you finish. It is a permanent tax. Every generator, refinery, and machine you add makes heat, so a mature colony runs one or more aquatuner loops forever, often on Super Coolant, as its standing heat sink. Insulation and Abyssalite hold the line around the base while the loops delete the heat inside it. A colony that has closed this loop can run essentially forever, which is the whole point of pushing through the wall.
Next: cool the hot SPOM oxygen output, understand the power generators that create the heat, and see where the wall sits in the crisis order cheatsheet.