Plant Utilities worked example
Boiler Efficiency Gap at 60% target boiler efficiency: a worked example
This worked example runs the boiler efficiency gap numbers for a tougher week than the baseline: 60% target boiler efficiency instead of the typical 84%. Compare measured boiler efficiency to the target so teams can see the efficiency gap that may justify tuning or maintenance.
The inputs for this scenario
- Target boiler efficiency: 60 % (the input this scenario stresses; the baseline uses 84)
- Measured boiler efficiency: 78 % (held at the documented default)
- Reference boiler efficiency: 84 % (held at the documented default)
Working through the calculation
- The calculation starts from the formula this tool documents: Efficiency gap = target boiler efficiency - measured boiler efficiency.
- Margin works out to -21.43 % at these inputs, and this is the headline figure for the scenario.
- Absolute margin works out to -18 value at these inputs.
- Available amount works out to 60 value at these inputs.
- Required amount works out to 78 value at these inputs.
How this compares with the baseline
- Against the tool's baseline example, where target boiler efficiency sits at 84% and the headline result is 7.14 %, this scenario comes in 400% below the baseline at -21.43 %.
- Use it right after a flue-gas analysis, seasonal combustion tune, or when comparing a boiler's current stack loss against its nameplate or ASME PTC 4 design efficiency. A result at this level usually justifies acting on the stressed input before touching anything else, because every other figure in the table is downstream of it.
Results at a glance
- Margin: -21.43 % (headline result)
- Absolute margin: -18 value
- Available amount: 60 value
- Required amount: 78 value
Run it with your numbers
- To rerun this with your own numbers, open the live Boiler Efficiency Gap calculator, set target boiler efficiency to your actual value, and adjust the remaining inputs to match your operation.
Last reviewed 2026-05-12.