Railcraft Steam Boiler Efficiency

[Recon]

Been using the Boiler as a primary source of buildcraft energy, which is amazing when combined with the Thermal Expansion redstone batteries. I have a question for anyone who has used these boilers, regarding efficiency.

On the official page for these devices, it says that low-pressure boilers are "more efficient". However, if you read farther down, in the math section, it works out that the high-pressure boilers produce twice as much energy, and they also use twice as much fuel. What that means essentially is that they are the same efficiency as the low-pressure boilers. They would produce the same amount of energy per fuel used regardless of whether you built the high or low pressure boilers.

The only real differences between the two seem to be (1) the max energy output for one boiler is twice as much for the high-pressure ones, and (2) the temperature must be raised to 1000 degrees before reaching peak efficiency. Perhaps this is what the site meant by LP boilers being generally more efficient? Is it just that you waste more fuel starting up a high-pressure one, but once its up to temp, the efficiency is the same? Am I understanding this correctly?

 

[Mikey_R]

I suspect it is to do with the efficiency of steam produced per time interval. So, while it has the same fuel/stream ratio, the steam produced per tick is higher, making it more efficient at producing the steam.

 

[Recon]

Well, the site says that the low pressure boiler is more efficient. The one that produces half the amount of energy.

 

[trondaron]

Is it just that you waste more fuel starting up a high-pressure one, but once its up to temp, the efficiency is the same? Am I understanding this correctly?

I believe that is correct, the efficiency difference is during warm up.

 

[Recon]

Ok that makes sense. Good thing I have an iron tank in my base with over 1000 buckets of fuel in it then ^_^

 

[Omicron]

I looked into that for a bit. Careful where you tread, for this path involves math. Functions with arguments that are best expressed as functions themselves...

I kind of stopped tinkering with it, first because of stress on the job, and now that I have vacation, Thaumcraft 3 got released. But maybe once I'm done with that...

Suffice to say, the heatup time and heatup fuel cost plays a major role, and low pressure boilers are indeed more efficient than their high pressure equivalents.

 

[Celestialphoenix]

What what I've gathered (wiki/forums)- when fully heated both HP and LP boilers have roughly the same steam:fuel ratio when fully heated up.

However from my test worlds I can tell you:

High Pressure boiler will use a lot more fuel (at least 4x as much) to reach its max temp. Also takes a lot longer to do so.

Both boilers will continuously burn fuel at their same rates regardless of how much steam is being used.

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So if you're not using all the steam, then you loose a fair bit of efficiency. As HP boilers use more fuel and make more steam this inefficiency is amplified.​

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As HP boilers make 2x as much steam, therefore a smaller steam boiler will produce the same as a larger LP boiler, at a worse steam:fuel ratio.​

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Therefore, unless you go full size and use it all, its generally more efficient to run a LP boiler.​

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In terms of resources and space, boilers can use a fair bit of iron- so if you're running low it may be cheaper to build a smaller HP boiler than a larger LP one.​

(A lot of mods use a lot of Iron- I frequently have more spare diamonds than I do Ingots.)​

 

[Busuwe]

When it comes to fuel efficiency you'll find that size do matter!
Bigger is better.
You will get about 64% more steam per unit of fuel from a 3x3x4 boiler than from a 2x2x2