| 1 Low Pressure Boiler | 1.0 | 1.0 | 1mb per 24 ticks | 1mb per 72 ticks | Small Coal Boiler | 6mb/t | All variants of (char)coal [10], (Bituminous) Peat | ~4 (char)coal | |
|---|---|---|---|---|---|---|---|---|---|
| 8 Low Pressure Boilers | 5.0 | 6.0 | 1mb per 4 ticks | 1mb per 11 ticks | HP Coal Boiler | 15mb/t | All variants of (char)coal [10], (Bituminous) Peat | ~17.5 (char)coal | |
| 12 Low Pressure Boilers | 7.0 | 9.0 | 3mb per 8 ticks | 1mb per 7 ticks | Reinforced Lava Boiler | 30mb/t | Lava [11] | ~7 lava buckets | |
| 18 Low Pressure Boilers | 10.0 | 15.0 | 3mb per 5 ticks | 1mb per 5 ticks | Simple Solar Boiler [7] | 6mb/t | Sunlight | ||
| 27 Low Pressure Boilers | 13.0 | 18.0 | 5mb per 6 ticks | 1mb per 4 ticks | HP Solar Boiler [7] | 18mb/t | Sunlight | ||
| 36 Low Pressure Boilers | 15.0 | 20.0 | 1mb per tick | 1mb per 3 ticks | Advanced Boiler (LV) [8] | 37.5mb/t | Any Furnace fuel [12] | N/A [13] | |
| Advanced Boiler (MV) | 75mb/t | Any Furnace fuel [12] | N/A [13] | ||||||
| 1 High Pressure Boiler [4] | 2.0 | 3.0 | 1mb per 10 ticks | 1mb per 30 ticks | Advanced Boiler (HV) | 112.5mb/t | Any Furnace fuel [12] | N/A [13] | |
| 8 High Pressure Boilers | 12.0 | 15.0 | 2mb per 3 ticks | 3mb per 13 ticks | |||||
| 12 High Pressure Boilers | 18.0 | 24.0 | 11mb per 12 ticks | 1mb per 3 ticks | Large Bronze Boiler | 800mb/t | |||
| 18 High Pressure Boilers | 24.0 | 32.0 | 13mb per 10 ticks | 9mb per 20 ticks | Large Steel Boiler | 2000mb/t | |||
| 27 High Pressure Boilers | 32.0 | 42.0 | 7mb per 4 ticks | 6mb per 10 ticks | Large Titanium Boiler [9] | 2666.65mb/t | |||
| 36 High Pressure Boilers | 40.0 | 54.0 | 9mb per 4 ticks | 3mb per 4 ticks | Large Tungstensteel Boiler [9] | 10666.65mb/t |
Notes: [1] Charcoal Pieces and Creosote Oil measure how many Coke Ovens, turning wood into charcoal, are required to keep a railcraft boiler at max temperature off of charcoal pieces/creosote oil (once heated up to max) [1] Note that the method of testing can lead to very long times before inconsistencies become apparent, so these numbers should be taken as a baseline for the absolute bare minimum required [2] Charcoal blocks are more fuel efficient than charcoal pieces (9 pieces to one block, one block has 10 pieces worth of burn time), at the cost of requiring a compressor to make [2] Solid Fuelled Boilers accept any standard furnace fuel. Buckets of fuel will return the buckets, cells of fuel will NOT return the cells [3] GT multiblock boilers suffer a hidious penalty to fuel efficiency when burning liquid fuels, making them greatly more efficient in Railcraft liquid boilers. Downside is that the latter takes hours to fully heat up [3] These values are for versions before 2.5.0. In 2.5.0 Creosote fluid was buffed to match it’s fuel value in bucket form, meaning creosote oil should feed the same number of liquid fuelled boilers as charcoal feeds solid fuelled boilers [4] In GTNH the numbers are tweaked such that High Pressure Boilers are actually more fuel efficient than Low Pressure Boilers - 4× the steam for slightly over 2x fuel cost [5] 9mb Ethanol every 4 ticks has a base fuel value of 432 EU/t. A max size high pressure boiler can feed 4.5 Railcraft Turbine Housings, which will produce 900 EU/t in total [6] 3mb Diesel every 4 ticks has a base fuel value of 360 EU/t. A max size high pressure boiler, still, can produce up to 900 EU/t with Turbine Housings [7] Solar Boilers will calcify over time, reducing steam output. To clear them simply break and replace them, although this will void all the stored water and reset them to 20C [7] I’m not sure how long it takes for solar boilers to clacify or whether there’s a random element to how long it takes, but it takes a fairly long time for it to start happening [8] Benefits (albeit slightly) from higher density fuels, not just from fuels with a burn value over 500 - 10 charcoal pieces produces less steam than 1 block of charcoal [9] Produces Superheated Steam instead of regular steam [10] Ztones Mini (Char)Coal does not work. Blocks of (char)coal (or variants thereof) do work [11] Lava can be pumped in as a fluid or supplied via buckets. Lava buckets are equally efficient and will return empty buckets, but cannot be automatically input/output [12] Advanced Boilers will accept buckets/cells of fuel, but will not return the buckets, cells, or other items. Fluid fuels cannot be pumped in [13] The Advanced Boilers only burn fuel when they’re below 100C. This behariour overall results in significantly greater fuel efficiency, yielding over twice the steam per piece of fuel as HP coal boilers do
GT Large Bronze Boilers require 37.5 coke ovens running 24/7 to stay active off of the produced charcoal pieces and creosote oil, Large Steel Boilers require 75 coke ovens. However, GT boilers have a (relatively) quick warmup period, so toggling them on/off when necessary and stockpiling fuel during downtime periods is viable
Tips and tricks: Railcraft tanks produce (Biome Humidity/10)mb water every 8 ticks. If it’s raining output is tripled. If the tank is considered “covered” - zero tank blocks receive full sunlight on top - the amount of water produced every 8 ticks is halved (rounded down if necessary) and the rain bonus is negated GT boiler will convert water into steam at a 1:160 ratio. Railcraft boilers seem to use the same conversion ratio, but have not been tested as thoroughly. In any case make sure there’s more than enough water production to keep your boilers going, lest one mistake has explosive concequences
Railcraft Steam Turbine Housings (and their accompanying rotors) are, functionally, (relatively) cheap and early multiblock steam turbines. Extract the power they produce from either 2×2 side of the multiblock with a Medium Voltage (or higher tier) Transformer in step down mode Steam Turbine Housing rotors consume up to 320mb steam per tick, have effectively 125% fuel efficiency, and produce up to 200 EU/t. Rotors require a short warmup period before they’ll produce full power, same as GT multiblock turbines Steam Turbine Housing rotors have durability. Limited testing tentatively suggests that they take high damage when spinning up and minimal damage when running full tilt, so invest in good power storage to limit how often they have to be toggled on/off Allowed to run at full tilt constantly a single rotor is able to produce over 1G EU before it finally breaks. Of course in practice you’ll not be able to store anywhere near that power until long after you’ve retired Turbine Housings completely, but it goes to show they can last a long time
Buckets of Creosote Oil can be used as a solid fuel source, including in solid fuelled Railcraft Boilers. The 250mb a Coke Oven produces has (functionally) the same fuel value as the piece of charcoal, so as of 2.5.0 you’ll need the same size fluid boiler as solid boiler if you’re burning both charcoal and creosote Creosote buckets in a solid fuelled boiler can be automated pre-LV. Use a hopper to extract the full/empty bucket, and use GT Item Pipes (Tin will suffice) to move the bucket to the right location if the hopper can’t do so directly. Though note you will need a steel wrench to harvest tin item pipes, so be careful
In GTNH there are a total of three furnaces that run off steam: GTs Steam Furnace and High Pressure Furnace, as well as Railcraft’s multiblock Steam Oven. Since NEI doesn’t neatly list the power costs for smelting things, here’s the TL;DR:
Steam Furances smelt one item every 12 seconds, and consume 8mb/t steam (160mb/s). High Pressure Furnaces smelt one item every 6 seconds, and consume 16mb/t steam (320mb/s). Steam Ovens smelt up to nine items every ~12.5 seconds, and consume 32mb/t steam (640mb/s) (For reference a regular furnace smelts one item every ten seconds, and consumes 200 burntime worth of fuel per item. Nether Furnaces are as fast as a regular furnace, but consume only 100 burntime per item. Iron Furnaces smelt one item every eight seconds, consuming 160 burntime)
Tips and tricks: A single LV Fluid Heater will produce 32mb/t steam, which is enough to fuel one Steam Oven and smelt up to ~0.72 items per second at effectively 30 EU/t. That same EU would power 7.5 LV electric furnaces, smelting 7.5 item every 6 seconds or ~1.25 items/s. In short it’s more power efficient to use LV electric furnaces than use a fluid heater to electrically fuel a steam oven…on paper. In practice there is cable loss/processing speed/material cost to consider, but more importantly, you will have to go through a steam age to reach the electric age in the first place. This will leave you with old steam production (and possible storage) infrastructure with no other use, so fuelling a steam oven on the cheap should be trivial. For reference it takes six calcified HP solar boilers to keep a steam oven running during daytime, and steam ovens only run when full on steam - they cannot void steam like GT steam machines
There’s also three different variants of single block electrical furnaces - furnace, oven and microwave - but you’re probably better off not experimenting with those too much. Furnaces and Ovens are identical stat-wise, just different looks, but while microwaves do smelt faster than furnaces they will also explode if you try to smelt the wrong item in them. Given the sheer practical efficiency of Steam Ovens your best bet is to rely on them until you can make Multi Smelters, the multiblock GT furnace, circa MV/HV