Firebox
A brick hole with a fire in it. Put fuel in and set a Crucible or Boiler on top.
Crafting
B B B
B B
B B B
B is a Brick.
Using it
- Right-click with fuel to load it.
- Right-click with an empty hand to take back fuel that hasn't started burning.
A lit firebox smokes and flickers. It doesn't heat anything itself. Whatever sits on top climbs toward the fire's temperature. See Heat.
Fuels
Only real fuels burn here, and an item burns because of what it's made of: logs, stripped logs, wood blocks and planks are all wood, and a plank is a quarter of a log. Nether stems and other mods' planks don't burn. Each one has its own flame temperature and burn time:
| Fuel | Flame | Fully blown | Lasts | Varies by |
|---|---|---|---|---|
| Sticks | 760 Tu | 1140 Tu | 4 s | 12% |
| Planks | 760 Tu | 1140 Tu | 7.5 s | 12% |
| Logs | 760 Tu | 1140 Tu | 30 s | 12% |
| Coal | 1180 Tu | 1770 Tu | 2 min | 10% |
| Charcoal | 1220 Tu | 1830 Tu | 80 s | 6% |
| Block of Coal | 1180 Tu | 1770 Tu | 18 min | 10% |
| Lava Bucket | 1200 Tu | 1800 Tu | 17 min | none |
| Blaze Rod | 1400 Tu | 2100 Tu | 2 min | 3% |
Wood fires are too cool for any metalwork. Coal and charcoal will melt copper (1000 Tu) and gold (950 Tu) but won't reach steel (1350 Tu) on their own.
Every piece of fuel burns a little differently. Each piece runs a bit hotter or cooler than the last, for its whole burn, so you'll notice good and bad batches. Lava doesn't vary at all.
Air
A Powered Bellows touching the firebox makes the fire up to 1.5× as hot. It doesn't make the fuel last longer. Air raises the fire relative to the fuel, so a cool fuel blown hard is still a fairly cool fire. Charcoal plus a bellows is how you reach steel temperatures, and fully blown it's 1830 Tu: well past where iron burns. The trick is knowing when to stop blowing.
The firebox holds a little air: about half a second of full burn. A full fire uses 4 mB of air a tick.
Lava instead
You can skip the firebox and put a crucible or boiler straight over lava. It's a fixed, perfectly steady fire, but it's not hot enough for steel and you can't blow it hotter.