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Stardew Valley Heavy Furnace Database
Heavy Furnace records for Mining Mastery crafting, 2 Furnaces, 3 Iron Bars, 50 Stone, 25 ore plus 3 Coal batches, 5-6 bar output, ore and Coal savings, Quartz, Fire Quartz, Skull Cavern, Radioactive Ore, and furnace lane layouts.
Heavy Furnace Unlock and Crafting
Unlock / Mining Mastery, 2 Furnaces, 3 Iron Bars, and 50 Stone
Heavy Furnace unlocks from Mining Mastery and is crafted with 2 Furnaces, 3 Iron Bars, and 50 Stone. Build it once the save has enough ore flow to process full 25-ore batches instead of one bar at a time.
25 Ore Batch Smelting Rules
Mechanics / 25 ore, 3 Coal, and 5-6 bars
For ore, Heavy Furnace consumes 25 ore and 3 Coal per run. Each batch has an equal chance to output 5 or 6 bars, so the average batch beats five ordinary furnace runs on both ore and Coal.
Ore and Coal Economy
Efficiency / Average 9% ore savings and 45% Coal savings
Compared with ordinary Furnaces, Heavy Furnace saves about 9% ore and 45% Coal on average when smelting bars. That makes it strongest for Iridium, Radioactive, and other high-volume mining routes.
Quartz and Fire Quartz Refining
Refining / 5 Quartz or 5 Fire Quartz plus 3 Coal
Heavy Furnace can also run 5 Quartz or 5 Fire Quartz with 3 Coal. Quartz yields 5-6 Refined Quartz, while Fire Quartz yields 15-20 Refined Quartz for sprinkler, crystal path, and crafting stockpiles.
Furnace Lane Layout and Throughput
Layout / Ore chest, Coal chest, regular Furnaces, and Heavy Furnace lanes
The cleanest layout keeps Heavy Furnaces beside ore and Coal chests, with ordinary Furnaces beside them for leftover stacks. This makes morning pickup, late-night dump, and shed-based bar production easier to repeat.
Skull Cavern and Radioactive Ore Planning
Late Game / Iridium, Radioactive Ore, Mining Mastery, and Dwarf King powers
Heavy Furnace turns deep mining days into efficient bar production. Use it after Skull Cavern Iridium dives, dangerous mine Radioactive Ore weeks, and Dwarf King ore or coal power days to compress late-game crafting costs.