Three inputs with different purposes
Place the result chest on the floor. Crouching, place the hopper with the spout in the chest with the furnace above it. Place the second hopper into the furnace from above, and the third from the side. Place separate chests above the two entrance hoppers. Reference: Minecraft: hopper.
hopper costs 5 iron ingots and a chest. For three you need 15 ingots and 3 chest; Another 3 chest serves the entrances and exits. The furnace requires 8 cobblestone. Redstone power is not required for this feed.
Test that finds a mixed up spout
Place 8 cobblestone in the top chest and 1 coal in the side chest. In the furnace interface, cobblestone should be on top, coal on the bottom. After work, the output chest should contain 8 stones.
If coal is in the raw material slot, fuel is supplied from above. If the finished stone remains in the kiln, check the bottom hopper, the free result space and the adjacent redstone: the powered hopper is blocked.
To connect the receiver to the chest, the following instructions will be useful: Hoppers: send items to the right container.
Fuel, experience and expansion
One coal melts 8 items in a normal furnace; 64 cobblestone requires 8 coal. The Smokehouse and Melting Furnace only accept their own recipe categories, so simply replacing the block will not make the stone faster.
To manually collect the result and experience of the furnace, temporarily block the lower hopper with the lever and process at least one more item. Then take the result yourself. Remove the lock before leaving. Higher speed requires parallel furnaces and distribution of raw materials; a long chain of funnels by itself does not increase the speed of the furnace.
The repair procedure with new experience is described separately: Mending in Minecraft: repair equipment with experience.
