Blaze Burner

It all starts with an Empty Blaze Burner, crafted from four iron sheets around a netherrack block. Then head to a Nether fortress: right-click a blaze with the empty burner in hand to trap it inside, or right-click a blaze spawner directly, which is safer and needs no fight. The filled burner can then be placed wherever you like, and it never empties. Mining it with a pickaxe gives you the burner back with its blaze still inside.

The burner's only job is to heat the block above it: a basin for the mixer or the press, or a Fluid Tank acting as a boiler. A resting blaze does not really heat anything; you have to feed it for heated recipes to work. When it is working under an active basin, it turns around and its flames come alive, which is a quick way to check that a recipe is really getting heat.

Right-click with any furnace fuel (planks, coal, logs, a lava bucket…) to make it kindled. It burns as long as in a furnace: 80 seconds for coal, 15 for a plank. When the reserve drops below 1.25%, it switches to fading, still hot enough for recipes and boilers. It only accepts new fuel once less than 25 seconds remain, so there is no point stacking it up by hand.

A Blaze Cake makes it superheated (blue flame) for 160 seconds, after which it stays kindled for another 250 seconds. Only a few recipes need it, like lava from cobblestone in the mixer, but a boiler counts a superheated burner as two heat levels. The cake takes two steps: compact an egg, sugar and Cinder Flour into a cake base, then fill it with 250 mB of lava using a Spout.

For a factory that runs without you, leave the feeding to a Deployer holding the fuel and pushing it into the burner, or to a Mechanical Arm fetching it from a chest. A funnel will not work: the burner has no inventory, so the fuel has to be handed over the way a player would.

An empty burner can also be lit with Flint and Steel: it becomes a nice fire lantern, without a blaze. Clicking it with soul sand or soul soil turns its flame blue. Keep in mind these lit burners only give weak passive heat, so they cannot replace a real Blaze Burner in a factory.