Furnace
Furnaces are used to smelt resources into usable products for further usage. This makes them a key building for development and automation. Starting with very basic stone furnaces the player can advance through research and replace them with more efficient and faster furnaces later in the game.
Furnaces can be affected by Beacons.
Types
| Type | Total raw | Speed | Maximum energy | Module slots | Size |
|---|---|---|---|---|---|
 |
 |
1 | 180 kW (burner) | 0 | 2 x 2 |
| |
|
2 | 180 kW (burner) | 0 | 2 x 2 |
| |
|
2 | 180 kW (electric) | 2 | 3 x 3 |
Usages
Multitask furnaces
The furnace chooses the used recipe by itself (it uses the recipe with the right input item). This behavior can be used to furnace, depending on what is currently needed/coming in.
See http://www.factorioforums.com/forum/viewtopic.php?f=5&t=5930&start=10#p47008 and ff.
Note, that this strategy is quite advanced, cause the inserters will fill normally the furnace up to 5 items, so especially when the output is blocked (cause too much produced) you cannot input (the more needed) item.
Technical details
Relationship to Assembling machine
Since v0.11 the furnaces are technically (c++ code) the same class. This means for example for modding, that a furnace should be able to use two input items.