Boiler Feedwater Heating Duty Calculator
Reviewed by Hamza Gujjar, Algorithm Architect & Software Developer
Last updated: July 26, 2026Boiler Feedwater Heating Duty Calculator
Preheating feedwater before it enters the boiler reduces thermal shock on boiler tubes and lowers the fuel needed inside the boiler itself.
The Formula
Q = ṁ × cp × ΔT
Worked Example
5 kg/s of feedwater, specific heat 4.2 kJ/kgK, raised 40K: Q = 5 × 4.2 × 40 = 840 kW.
How to Use This Calculator
- Enter feedwater mass flow rate.
- Enter feedwater specific heat (roughly 4.2 kJ/kgK for water).
- Enter the target temperature rise.
Related: Boiler Economizer Heat Recovery Calculator, which often supplies this exact heat.