Plant optimization calculator · Updated 17 September 2026
Boiler Economizer Duty Calculator — Feedwater Heat Recovery & Fuel Savings
Calculate feedwater preheat duty, annual recovered heat and equivalent fuel saving from water flow, inlet/outlet temperature, boiler efficiency and fuel heating value.
Inputs
Live results
- Recovered sensible heat 290.69444 kW
- Equivalent fuel saving 27.359477 kg/h
- Annual recovered heat 1,744.1667 MWh
- Annual fuel equivalent 164.15686 t
- Annual indicated value 82,078.431
Formula
Q=ṁCp(Tout−Tin); fuel saved=Q/(η×HV).
Worked example
10 t/h feedwater heated by 25 K recovers about 291 kW.
Assumptions and limits
- Liquid-water Cp is approximated at 4.186 kJ/kg·K.
- Confirm stack outlet temperature remains above the applicable corrosion/dew-point limit.
FAQs
What does this Boiler Economizer Duty Calculator calculate?
Calculate feedwater preheat duty, annual recovered heat and equivalent fuel saving from water flow, inlet/outlet temperature, boiler efficiency and fuel heating value.
Can I use this for a final design?
Use it for screening, diagnostics and opportunity sizing. Validate final design against measured plant data, OEM limits and applicable standards.
Why does the calculator show intermediate results?
Intermediate engineering quantities make bad inputs and unrealistic assumptions easier to spot before a decision is made.