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Plant Engineering Calculator

Updated Sep 18, 2026

Boiler Oxygen Trim Savings Calculator — Excess O₂, Fuel Reduction & Payback

Screen boiler oxygen-trim economics from measured fuel use, proposed fractional fuel reduction, operating hours and fuel price, with annual fuel, cost and simple-payback outputs.

Live calculationWorking shownPrivate in browser

Inputs

Results

Fuel saved 7.50 kg/h
Annual fuel saved 45000 kg
Annual cost saved $22500
Simple payback 0.44 years
More actions

Shared links reopen these inputs. Recent and saved calculations stay in this browser unless you clear site data.

Formula

fuel saved=baseline fuel×saving fraction; annual saving=fuel saved×hours×fuel price.

Your calculation, step by step

These steps use the values currently entered above so the result can be checked independently.

  1. 1.Validated fuel-saving fraction = 1.500% ÷ 100 = 0.01500.
  2. 2.Fuel saved = 500.00 × 0.01500 = 7.5000 kg/h.
  3. 3.Annual fuel saved = 7.5000 × 6000 = 45000.0 kg; value = 45000.0 × $0.5000 = $22500.00.
  4. 4.Simple payback = $10000.00 ÷ $22500.00/year = 0.444 years.

How to use this calculator

  1. Enter measured or design values using the units shown beside each field.
  2. Review the live results and the substituted calculation steps before using the estimate.
  3. Check the assumptions below, then continue to a related calculator when the next engineering decision needs another model.

Worked example

A boiler burning 500 kg/h with a validated 1.5% trim opportunity saves 7.5 kg/h at the same useful duty.

Assumptions and limits

  • Fuel-saving fraction must come from combustion testing or a defensible before/after model.
  • Never reduce excess air below safe combustion, CO, emissions or burner/OEM limits.

How to interpret the result

Treat the primary result as an engineering screening value, then use the secondary outputs to understand scale, energy or operating impact. Confirm site measurements, equipment limits and applicable standards before making a design or control change.

Questions engineers ask

Can excess O₂ alone determine the fuel-saving percentage?

Not safely. Stack O₂ is a combustion diagnostic, but the realizable fuel reduction depends on burner condition, excess air, flue-gas temperature, fuel, CO/emissions and load. Enter a saving fraction supported by combustion testing or a defensible before/after model.

Why is oxygen trim a safety-sensitive adjustment?

Reducing excess air too far can create incomplete combustion, CO, soot, unstable flame and emissions problems. Burner/OEM limits and combustion-safety procedures remain authoritative; this owner only annualizes an already-validated fuel-saving opportunity.

What does simple payback omit?

It divides installed project cost by annual entered fuel-value saving. Financing, maintenance, sensor calibration, escalation, downtime and degradation are outside this simple screening metric.

Continue the calculation

Use the next calculator in the same engineering workflow instead of restarting from search.

boiler excess airboiler efficiencyboiler fuel comparison
Methodology. MAXScanner shows the governing formula, entered values and calculation outputs so the estimate is auditable. The calculator is a screening aid; assumptions and equipment-specific limits remain part of the engineering review.