Steam Boiler Statistics

This page holds detailed operational information about Steam Boilers.

Current (Railcraft 9.x.x.x)

In Railcraft 8.3.0.0, boilers were rebalanced, with their formulas changed significantly, most notably with fuel consumption during heat-up. Boilers no longer consume massive amounts of fuel when cold, but instead consume slightly less fuel when cold. On the other hand, boilers now produce less steam when not fully heated up, and high-pressure boilers now consume more fuel per unit steam than low-pressure boilers.

Overall, boilers are nerfed compared to the previous formula, but are still several times more efficient than tier 1 options such as the Hobbyist's Steam Engine on its own or the Generator.

Power generation

Steam engines generate 2 MJ/t for each low pressure boiler block. High pressure boiler blocks generate twice as much energy. The amount of steam, and thus power, generated is proportional to the temperature, except below 100 degrees, where no steam is produced.

Boilers	Heat/c (L|H)		Steam/c	Steam/Heat (L|H)		MJ/Heat* (L|H)		EU/Heat* (L|H)		RF/Heat* (L|H)		Steam/t (L|H)		MJ/t* (L|H)		EU/t* (L|H)		RF/t* (L|H)
1	10.7	12.7	160	14.95	12.60	2.99	2.52	9.35	7.87	29.91	25.20	10	20	2	4	6.25	12.50	20	40
8	80.0	96.0	1280	16.00	13.33	3.20	2.67	10.00	8.33	32.00	26.67	80	160	16	32	50.00	100.00	160	320
12	115.2	139.2	1920	16.67	13.79	3.33	2.76	10.42	8.62	33.33	27.59	120	240	24	48	75.00	150.00	240	480
18	162.0	198.0	2880	17.78	14.55	3.56	2.91	11.11	9.09	35.56	29.09	180	360	36	72	112.50	225.00	360	720
27	218.7	272.7	4320	19.75	15.84	3.95	3.17	12.35	9.90	39.51	31.68	270	540	54	108	168.75	337.50	540	1080
36	259.2	331.2	5760	22.22	17.39	4.44	3.48	13.89	10.87	44.44	34.78	360	720	72	144	225.00	450.00	720	1440

Assuming maximum temperature. Heat costs are reduced slightly when cold, but less steam is produced.

* after being converted using a Railcraft Engine (MJ/RF) or Steam Turbine (EU)

Fuel usage

Boilers	Heat/t (L)	Heat/t (H)	Efficiency* (L)	Efficiency* (H)
1	0.669	1.588	100%	84%
8	5.000	12.000	107%	89%
12	7.200	17.400	111%	92%
18	10.125	24.750	119%	97%
27	13.669	34.088	132%	106%
36	16.200	41.400	149%	116%

*Compared to 1LP Boiler

A LP boiler consumes 0.675 HU/t per boiler block, while a HP boiler consumes roughly 1.6 HU/t per boiler block. These values are reduced by 0.00625 HU/t and 0.0125 HU/t for each boiler block, respectively. Thus, a 36LP boiler consumes a third less fuel per steam (0.45 HU/t).

The formula for the amount of fuel consumed per block per boiler cycle is as follows: Fuel (hU) = 8 - 0.1*numTanks + 0.8*(heat/maxHeat) + 4*(maxHeat/1000)

The first term is a base term, while the second term is the size bonus, the third is the heat penalty, and the fourth is the pressure penalty. To get the fuel per tick, this term is multiplied by the number of boiler blocks, then divided by the length of the boiler cycle (16 for LP, 8 for HP). Note the following:

• The pressure penalty makes HP boilers consume more fuel per steam than LP boilers, thus HP boilers are less fuel-efficient. This is compensated by the increased space and resource (iron) efficiency of HP boilers per unit power. A small LP boiler consumes 10.8 HU/cycle at full heat, while a small HP boiler consumes 12.8 HU/cycle (19% more).
• Larger boilers are more efficient. In particular, the 36LP boiler is the most efficient boiler. A 36LP boiler consumes 7.2 HU/cycle, while a 36HP boiler consumes 9.2 HU/cycle (28% more than the 36LP).
• Boilers consume slightly less fuel when not at full heat (0.8 HU/cycle less when cold).

The biggest change from legacy versions is that boilers no longer consume a massive amount of fuel to heat up. They still need fuel to heat up and still need the same amount of time, but it is no longer necessary to stockpile a large amount of fuel for the heatup process - one may start up a boiler as soon as fuel is being produced at a sufficient rate to maintain it at steady state.

High pressure boilers consume twice as much fuel per tick and have twice as far to heat up, so heating up a high pressure boiler take about four times as much initial fuel to hit their final temperature.

At full temperature, fuel efficiency can be further improved by not burning fuel constantly. Since the cooldown process around full temperature is 4 times faster than the heating process, up to 20% fuel can be saved by letting the temperature drop periodically upon reaching full temperature. Since steam production decreases with decreasing temperature, those periods have to be kept short to get an increased efficiency of close to 25%.

Resources needed to keep a chunkloaded, maximum size, low pressure boiler going for 1 day:

Resource	Units / 24 hours
Fuel	583
Bio Fuel	1750
Coal Coke	8748
Coal, Charcoal	17496
Creosote Oil	5832
Lava	27994

Heat generation

Low Pressure to 100°C to 500°C Boilers Ticks Fuel Ticks Fuel 1 440 276 4,519 2,941 8 3,522 16,420 36,156 175,576 12 5,282 35,361 54,233 378,775 18 7,924 74,214 81,350 797,332 27 11,885 148,930 122,025 1,608,672 36 15,847 232,674 162,700 2,530,393

High Pressure to 100°C to 1000°C Boilers Ticks Fuel Ticks Fuel 1 419 627 9,141 14,170 8 3,352 37,754 73,130 855,690 12 5,028 81,929 109,694 1,859,485 18 7,542 174,158 164,542 3,961,711 27 11,313 357,494 246,813 8,164,156 36 15,083 574,457 329,083 13,181,268

Note: Values in the above table are based on integration and are approximate. Actual results will vary somewhat due to the discrete nature of the boiler formula (i.e. runs once per tick).

The time required to heat up a boiler is roughly 3.8 minutes per boiler block with a continuous supply of fuel. High pressure boiler blocks take twice as long because they have twice the maximum heat. The rate at which the temperature increases is a linear function of the temperature - from 4 degrees per second divided by the number of blocks at zero temperature, to 1 degree per second divided by the number of blocks at maximum temperature.

These numbers are reversed when losing heat due to insufficient fuel: 4 degrees per second at maximum temperature, 1 degree per second at zero temperature, again divided by the number of blocks.

Legacy (Railcraft 6.11.x.x - 7.1.x.x)

Power generation

Steam engines generate 2 MJ/t for each low pressure boiler block. High pressure boiler blocks generate twice as much energy. Temperature does not affect energy generation unless the temperature is below 100°C, in which case no energy is generated.

Boilers	Heat/c	Steam/c	Steam/Heat	MJ/Heat*	EU/Heat*	Steam/t (L|H)		MJ/t* (L|H)		EU/t* (L|H)
1	6.32	160	25.32	5.06	7.91	10	20	2	4	3.13	6.25
8	46.08	1280	27.78	5.56	8.68	80	160	16	32	25.00	50.00
12	65.28	1920	29.41	5.88	9.19	120	240	24	48	37.50	75.00
18	89.28	2880	32.26	6.45	10.08	180	360	36	72	56.25	112.50
27	114.48	4320	37.74	7.55	11.79	270	540	54	108	84.38	168.75
36	126.72	5760	45.45	9.09	14.20	360	720	72	144	112.50	225.00

Assuming maximum temperature. Heat costs can be up to 884% of values listed when cold (20°C)

* after being converted using a Railcraft Engine (MJ) or Steam Turbine (EU)

Fuel usage

Boilers	Heat/t (L)	Heat/t (H)	Efficiency
1	0.395	0.790	100%
8	2.880	5.760	110%
12	4.080	8.160	116%
18	5.580	11.160	127%
27	7.155	14.310	149%
36	7.920	15.840	180%

Steam boilers consume ~0.4 HU/t for each boiler block when running at full temperature. There is then a 1.25% effeciency bonus per boiler block subtracted from this. So a full sized (36 block) furnace would use only 55% of the fuel. Whether or not the steam is being pumped out of the boiler does not affect the fuel consumed. High power boiler blocks consume twice the fuel and generate twice the energy, but do not get twice the efficiency bonus.

Steam boilers consume additional fuel when heating up. The amount of additional fuel consumed is equal to the standard fuel use plus ( 8 * <remaining heat percentage> ) This means that a cold boiler will consume almost 9 times as much fuel as a hot boiler. A boiler at half heat (250 for low pressure, 500 for high pressure) will consume 5 times as much fuel.

High pressure boilers consume twice as much fuel per tick and have twice as far to heat up, so heating up a high pressure boiler take about four times as much initial fuel to hit their final temperature.

At full temperature, fuel efficiency can be further improved by not burning fuel constantly. Since the cooldown process around full temperature is 4 times faster than the heating process, up to 20% fuel can be saved by letting the temperature drop periodically upon reaching full temperature. Since fuel consumption increases with decreasing temperature, those periods have to be kept short to get an increased efficiency of close to 25%.

Resources needed to keep a chunkloaded, maximum size, low pressure boiler going for 1 day:

Resource	Units / 24 hours
Fuel	214
Bio Fuel	856
Coke Coal	2138
Coal, Charcoal	4277
Charcoal	8554
Creosote Oil	8554
Lava	13688

Heat generation

Low Pressure to 100°C to 500°C Boilers Ticks Fuel Ticks Fuel 1 400 1,275 5,108 7,580 8 3,200 74,127 40,866 440,644 12 4,801 157,981 61,300 936,205 18 7,201 323,733 91,949 1,920,345 27 10,800 621,357 137,926 3,693,443 36 14,400 917,028 183,900 5,450,849

High Pressure to 100°C to 1000°C Boilers Ticks Fuel Ticks Fuel 1 400 2,695 10,317 30,921 8 3,200 157,056 82,533 1,802,285 12 4,801 334,268 123,799 3,829,687 18 7,201 685,360 185,700 7,856,377 27 10,800 1,316,786 278,550 15,110,593 36 14,400 1,943,419 371,400 22,301,396

The time required to heat up a boiler is 4.25 minutes per boiler block with a continuous supply of fuel. High pressure boiler blocks take twice as long because they have twice the maximum heat. The rate at which the temperature increase happens is 4 degrees per second for the first quarter (20 to 125 degrees in the low pressure boiler,) 3 degrees per second for the second quarter, 2 degrees per second for the third, and 1 degree per second for the last quarter divided by the number of boiler blocks.

These numbers are reversed when losing heat due to insufficient fuel: 4 degrees per second for the last quarter, 3 for the third, 2 for the second, and one for the first (also divided by the number of blocks.)