Alchemy Factory heat and fuel explained (1.1)

Machines that need heat, such as the Crucible, Kiln and Athanor, can only be built on top of a heating device: a Stone Furnace (from Level III), a Blast Furnace (Level IV) or a Steam Heating Pad (Level VI). The in-game manual measures heat in Pyra, shown as P.

Each heated machine draws heat at a rate listed in-game as Heat Consuming Speed. For most machines it is fixed (the Cauldron's depends on what it brews, and the in-game description says an Advanced Athanor running a standard Athanor recipe draws the same as an Athanor): at base speed it ranges from 4 P/s for a Crucible to 1,200 P/s for a Paradox Crucible. Every fuel has a Heat Value: a Plank holds 20 P, Coke Powder 660 P. The furnace adds up the draw of every machine on it and burns fuel to match. That gives two formulas:

• Seconds one fuel item lasts = heat value ÷ total draw.
• Fuel per minute = total draw × 60 ÷ heat value.

Example: a Kiln draws 15 P/s. One Charcoal Powder (48 P) lasts it 3.2 seconds, so the Kiln burns 18.8 Charcoal Powder a minute. You can refuel by hand or by conveyor belt; the game lists one belt input on each furnace. Every machine's draw is in the machine heat table.

The 1.0 patch notes say: “Removed the base heat cost of all heating devices.” Before that, every heating device also burned heat on its own. Players quoted 1 P/s for a Stone Furnace (Steam thread, January 2026 (opens in a new tab)), and the 0.5.4467 notes list a cost for the Steam Heating Pad: “Steam Heating Pad heat consumption speed reduced: 20 → 12.”

So if a forum answer adds a cost for the furnace itself, it was written before 1.0. Drop that part and check the rest again. Black Powder figures from before June 2026 are stale too: the 0.5.4467 notes say “Due to recipe changes, Black Powder's sell price and heat value have both been doubled.”

Each step up the ladder packs more heat into one item. The last column is the heat one fully loaded belt delivers at base speed (60 items a minute). A belt-fed furnace can only burn what arrives on that belt, so this column tells you when a fuel stops being enough.

Charcoal Powder gives you about twice as much heat per copper; Coke Powder carries about 14 times as much heat per belt slot. Here is what each copper buys once you subtract the heat the production steps burn:

• Logs cost 200200 copper each, and a Table Saw cuts one into 200 Planks. Burned as they are: 20 heat per copper.
• Bake the Planks into Charcoal in a Crucible and grind it: each Charcoal Powder holds 48 heat, but the Crucible burns 16 making it. That leaves 32 per item, or 32 heat per copper.
• Coal Ore costs 48004 silver 800 copper, and a Stone Crusher turns it into 120 Coal: 13.5 heat per copper.
• Bake the Coal into Coke in a Crucible (24 heat each) and grind it: Coke Powder nets 636 heat per item, or 15.9 heat per copper.

A Charcoal Powder line spends a third of the heat it makes on its own Crucibles. Size the line with that in mind.

Don't make Coke from Charcoal Powder for fuel. In an Athanor, 6 Charcoal Powder (288 heat) become 0.5 Coke and 1 Charcoal on average, worth 378 heat once ground. The Athanor burns 96 heat per craft, so the trade nets −6 heat. Make Coke this way only when you need the Coke itself.

Baking Coal into Coke does pay: the alternate Coke recipe in a Crucible gains +36 heat per Coke after the Crucible's 24.

You will build a Coke Powder line anyway: Brandy, Steel Ingot and Transformation Potion use it as an ingredient.

Switch when one belt of your fuel can't cover the machines on a furnace. One base-speed belt of Charcoal Powder carries 48 P/s. That runs 12 Crucibles, 3.2 Kilns or 1.5 Athanors, but covers only 44% of one Alembic (the Alembic draws 108 P/s).

A belt of Coke Powder carries 660 P/s: enough for 6.11 Alembics or 1.83 Advanced Athanors running their own recipes (360 P/s each). A Paradox Crucible draws 1,200 P/s, or 1.82 belts of Coke Powder, while one belt of Black Powder carries 6,000 P/s.

Before you switch, two cheaper fixes: give the big machine its own furnace, or raise belt speed (next section). The heating calculator gives fuel per minute for any mix of machines.

Three upgrades change the fuel math:

• Factory Efficiency adds 25% Device Production Speed and 25% Heat Consuming Speed per level for 12 levels, then 5% of each per repeatable level. Machines work faster and draw more heat per second, but the heat per item they make stays the same.
• Fuel Efficiency adds 10% Fuel Heat Value per level for 12 levels, then 10% per repeatable level. With all 12 levels before the repeatable one, every fuel gives 2.2 times its base heat, so you need 45% of the fuel. Players report that the bonus shows up in each fuel's Heat Value: with four levels, Charcoal Powder counts as 67.2 P instead of 48 (Steam thread, September 2026 (opens in a new tab)).
• Logistics Efficiency adds 15 items a minute to every belt per level for 12 levels, 25% of the base 60. Its 12 levels bring belts to 240 a minute, and a repeatable level after them adds 3 a minute each time. Each level, the repeatable one included, adds the same share of belt speed as the same Factory Efficiency level adds to heat draw, so raising both together keeps a fuel belt matched to the machines it feeds.

All three are in the upgrade list, and the heating calculator takes your Fuel Efficiency level.

Players report that steam doesn't make extra heat. It moves heat through pipes, so machines far from your fuel need no fuel belt.

A Steam Boiler (Level VI) turns heat into Steam at one of three settings. Community research puts every setting at 20 heat per Steam (research notes (opens in a new tab)), the same as Steam's own heat value in the game's item list. Low draws 100 P/s for 300 Steam a minute, Mid draws 500 P/s for 1,500 Steam a minute and High draws 3,000 P/s for 9,000 Steam a minute (all settings).

A Steam Heating Pad (Level VI) is the fuel-free heating device: machines on it are heated by the Steam it is fed. The in-game manual says liquids and gases travel through pipelines, so the Steam reaches the pad by pipe; the game lists no belt input for it. It has the Stone Furnace's 3×3 footprint but is only one block tall (the furnace is three).

How much Steam a pad uses per unit of heat isn't confirmed for 1.0, but players who tested it after the update report getting back the heat they put in (Steam thread, September 2026 (opens in a new tab)). Like the furnaces, the pad lost its base cost in 1.0.

Plan fuel for the boilers: High draws 3,000 P/s, which is 4.55 belts of Coke Powder or half of a belt of Black Powder. One belt of Coke Powder can feed Low and Mid.

Three late fuels are also shop goods, so burning one gives up its sale. Next to each sell price (base, before Shop Recognition bonuses) is what the same heat costs as Coke Powder made from Coal Ore:

• Black Powder: 6,000 heat, sells for 660660 copper; as Coke Powder about 377377 copper.
• Blast Potion: 24,000 heat, sells for 25572 silver 557 copper; as Coke Powder about 15091 silver 509 copper.
• Panacea Potion: 320,000 heat, sells for 3030 silver; as Coke Powder about 2012620 silver 126 copper. It is also a fertilizer.

Black Powder is the big step up the ladder: one uses 12 Charcoal Powder (576 heat) plus Sulfur Powder and Limewater, and holds 6,000 heat, about 10 times what the Charcoal Powder held. Burn it where you need the density; the profit table shows what each one earns when you sell it instead.

How many machines one furnace heats depends on its heating area, which this site doesn't list; the in-game description gives the Blast Furnace the larger one. For scale, the game lists these footprints: Stone Furnace 3×3, Blast Furnace 7×6, Crucible 2×1, Kiln 3×3 and Athanor 2×2.

Players commonly put three Crucibles or one Kiln on a Stone Furnace (Steam thread, November 2025 (opens in a new tab)). Those draw 12 and 15 P/s, or 15 and 18.8 Charcoal Powder a minute, well within one belt. For any other mix, add the machines to the heating calculator and check the placement preview in-game.