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Plant Engineering Calculator

Updated Sep 17, 2026

Boiler Feedwater Temperature Savings Calculator — Fuel & Cost Reduction

Quantify boiler fuel energy avoided when feedwater temperature increases at the same steam production rate.

Live calculationWorking shownPrivate in browser

Inputs

Results

Temperature gain 20.0 K
Boiler duty avoided 348.8 kW
Fuel input avoided 410.4 kW
Annual fuel energy avoided 2462353 kWh
More actions

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

Formula

Q=m·Cp(T2−T1)/3600; fuel input saved=Q/η.

Your calculation, step by step

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

  1. 1.Feedwater rise = 100.0 − 80.0 = 20.0 K.
  2. 2.Useful duty avoided = 15000 × 4.186 × 20.0 ÷ 3600 = 348.8 kW.
  3. 3.Fuel input avoided = 348.8 ÷ 0.850 = 410.4 kW.

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

Raising 15,000 kg/h feedwater by 20 K saves about 349 kW of boiler output duty, or more fuel input after efficiency correction.

Assumptions and limits

  • Assumes steam output and other boiler losses remain unchanged.
  • Use measured overall efficiency for economic screening.

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

Why does hotter boiler feedwater save fuel?

Hotter feedwater enters with more sensible energy, so the boiler must add less heat to produce the same steam output, assuming the rest of the operating condition is unchanged.

Should I use feedwater flow or steam flow?

Use the actual feedwater flow represented by the temperature increase. If only steam flow is known, account for blowdown and other water-side flows before treating it as feedwater flow.

Does this calculation include condensate-return benefits?

Only indirectly if the higher entered feedwater temperature came from condensate return. Water, treatment-chemical and flash-loss savings require separate accounting.

Continue the calculation

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

boiler economizer savingsboiler feedwater heating dutycondensate recovery energy savings
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.