ClueLuma

Boiler fuel saving fraction calculator

Fraction of original fuel input avoided is calculated as 1 − η_old / η_new. Use the stated system boundary and matching input units.

Fractionsaved=1−ηoldηnew\text{Fraction}_{\text{saved}} = 1 - \frac{\eta_{\text{old}}}{\eta_{\text{new}}}

Calculator

Enter the values you know and leave one box empty. Calculate finds the empty one, the result or any input.

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Worked example

Given

  • ηold\eta_{\text{old}} = 0.78 —
  • ηnew\eta_{\text{new}} = 0.85 —
Fractionsaved=1−0.780.85≈0.0824\text{Fraction}_{\text{saved}} = 1 - \frac{0.78}{0.85} \approx 0.0824

Symbols and units

SymbolMeaningUnit
Fractionsaved\text{Fraction}_{\text{saved}}fraction of original fuel input avoided—
ηold\eta_{\text{old}}original efficiency on the stated fuel basis—
ηnew\eta_{\text{new}}new efficiency on the stated fuel basis—

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Results are estimates for study and screening. Check the inputs, units and assumptions before you use them for design, billing or contract decisions.