Translations:Getting Started (GregTech 6)/87/en

For instance a Steel Burning Box is mildly powerful (32 HU/t), but it has an efficiency of 70%, while an Invar Burning Box, although less powerful (16 HU/t), has an outstanding 100% efficiency. The efficiency means your fuel will last more, and since you'll be burning a lot of fuel, having a perfect efficiency may sometimes be more important than raw heating power. Or course nothing prevents you from using a Burning Box at some point and then replace it for another one, under the same Boiler.