Railcraft Boiler

Note: this is accurate as of GTNH 2.1.2.0

The two Railcraft Boilers (Solid Fueled Boiler Firebox and Liquid Fueled Boiler Firebox) function essentially the same, just taking different kinds of fuels. The steam production and water consumption of the boilers is straightforward: each low-pressure tank produces 10L steam/tick at max heat and the high-pressure produces 20L steam/tick ; and each 160L of steam produced consumes 1L of water. The fuel consumption uses a complicated formula, scaling non-linearly with the number and type of tanks and the current heat of the boiler. Below is a summary of the fuel consumption per tick for max-heat boilers:

So, for example, one piece of charcoal (1600 burn time) in a solid-fueled firebox with 3x3x3 low-pressure boiler tanks lasts $$1600/13.66875 \approx 117$$ ticks, and a bucket of creosote (4800 burn time ) in a solid-fueled firebox with 3x4x3 high-pressure tanks lasts $$4800/41.4 \approx 116$$ ticks.

Note that this math refers to the consumption at max heat. The fuel consumption increases with heat, but not linearly. The fuel efficiency (amount of steam generated for each unit of fuel consumed) significantly increases with heat. For example, a max heat boiler with 3x4x3 high-pressure tanks produces twice as much steam as a similar boiler at half-heat, but it consumes only 5% more fuel. This ratio depends on the type and amount of steam tanks.