Heat
Heat is what limits how much a ship can run at once. Modules and engines produce it, the reactor sheds it, and a ship that lets it reach the top shuts down. Only player ships have heat. NPC ships do not.
The tutorial puts it this way: "Reactor temp's live. More you've got running, more heat builds up. Systems run best inside optimal."
Capacity and dissipation
A hull has a maximum heat capacity, between 425 and 577.5 GJ, and sheds between 4.5 and 5.5 a second. Ships lists both for every hull. Hull quality, modules, ciphers and affinity change them.
After three seconds without producing any heat, dissipation doubles until heat is produced again.
What produces heat
- Modules. Each active module adds its heat generation while it runs: during a cycle for modules that cycle, while it has a target for those that do not, and while the battery is firing for turrets. A mining laser only heats while the beam is on a valid target.
- Engines. Thrusters add 4.65 a second at full throttle on every hull, in proportion to throttle. Running the harpoon winch counts as full throttle.
- The Heat Spiked status multiplies module heat by 1.5.
- Brood eggs. Near The Brood Queen, every live egg heats every pilot in range.
Control rods and zones
Every hull has 10 control rods: 3 cool, 4 optimal and 3 unstable. They divide the heat bar into three zones.
| Zone | With all ten rods |
|---|---|
| Cool | Below 30% of max heat |
| Optimal | 30% to 70% |
| Unstable | 70% and above |
Entering the Unstable zone is an overheat. It fires any on-overheat effects on the ship and switches Auto Venting on, if one is fitted.
SCRAM
The SCRAM threshold is the share of rods you have left. With all ten it is 100% of max heat. When heat reaches it:
- one of the remaining rods, picked at random, is burned;
- heat drops to zero and is held there for 3 seconds;
- throttle and steering are cut;
- every active module that is not a turret is switched off, and turret batteries are suspended. A harpoon that is attached stays attached;
- your signature grows by 1,500 for the length of the shutdown.
A burned rod lowers the next SCRAM threshold by a tenth of max heat and shrinks the zone that rod belonged to. Rods stay burned between sessions until repaired: 10 ORE each at any refit terminal you are authorized at.
With no rods left the reactor is starved. The boost drive and every module that would produce heat stop working. The drift drive still works.
The heat bar's status words are Cool, Optimal, Danger, Critical, SCRAM Imminent, Purging, SCRAM, Initiating and Starved.
Why Optimal matters
Many modules work better while the reactor is in the Optimal zone.
| Module | In the Optimal zone |
|---|---|
| Auto-Cannon, Flak Cannon, Railgun | Fire about 10% faster |
| Rampart Gatling, Vanguard Lance | Fire 25% faster |
| Armor, Heavy, Patch and Ancillary Repairers | Cycle time 25% shorter. In the Cool zone it is 25% longer. |
| Mining Laser | Mining speed +25% |
| Armor Hardener | Kinetic damage reduction rises from 35% to 45% |
| Auto Venting, Hydro Injection | Their heat dissipation bonus is 25% larger |
| Sonar Ping, Tracking Computer | Their sensor range bonus is 25% larger. Tracking Computer's tracking bonus too. |
| Target Painter | Its signature increase on the target is 25% larger |
| Micro-Thrust Drive (boost) | Produces less heat in Optimal and more in Cool and Unstable |
Modules that manage heat
| Module | Slot and shape | Effect |
|---|---|---|
| Auto Venting | Subsystem, 1 by 2 | Switches on by itself at overheat. Heat dissipation 13 times normal, turning halved. 3 second cycle, 30 second cooldown. |
| Heat Purge System | Subsystem, 1 by 3 | Heat dissipation 8 times normal, kinetic resistance lowered by 40 points while it runs. 45 second cooldown. |
| Hydro Injection | Subsystem, 1 by 1 | Heat dissipation 17 times normal, signature +30%. 2 second cycle, 15 second cooldown. |
| Coolant Reservoir | Core, 1 by 2 | Max heat +15%, heat dissipation +4%, mass +3%, 4 fewer cargo slots. |
| Thermal Lattice | Core, 1 by 2 | Heat dissipation +16%, max heat +5%, mass +2%, signature +5%. |
The three purge modules switch themselves off when heat reaches zero, and will not start at zero heat.
Time to SCRAM
The fitting screen's Time to SCRAM is max heat divided by net heat under full load, shown as minutes and seconds or as Stable. Full load means every active module running at once. It leaves out engine heat, so in flight the real figure is shorter.