Game wiki
Stardew Valley Heavy Furnace
Heavy Furnace guide 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 layout planning.
Quick facts
Heavy Furnace unlocks from Mining Mastery and is crafted with 2 Furnaces, 3 Iron Bars, and 50 Stone.
Ore batches consume 25 ore and 3 Coal, then output 5 or 6 bars with equal odds.
On average, Heavy Furnace saves about 9% ore and 45% Coal compared with ordinary Furnaces.
Batch the ore that actually matters
Heavy Furnace is a late-game batching tool. It shines when ore arrives in bulk from Skull Cavern, dangerous mines, Volcano-adjacent routes, or Dwarf King ore days, then turns those stacks into bars with less Coal pressure.
- Use it for Iridium and Radioactive Ore before low-pressure ore stacks.
- Keep ordinary Furnaces for leftover stacks under 25 ore.
- Pair the machine with coal recovery plans so 3-Coal batches never stall.
Use Quartz routes deliberately
The machine also refines 5 Quartz or 5 Fire Quartz with 3 Coal. Quartz gives 5-6 Refined Quartz, while Fire Quartz gives a larger 15-20 Refined Quartz burst for crafting-heavy farms.
- Batch Quartz when sprinklers, Lightning Rods, or crystal paths are blockers.
- Save Fire Quartz for large Refined Quartz stockpile days.
- Store ore, Quartz, Fire Quartz, and Coal beside the furnace lane to reduce sorting time.