Boiler Feedwater Heating Duty Calculator
Reviewed by Hamza Gujjar, Algorithm Architect & Software Developer
Last updated: July 26, 2026
📚 Confused about how this is calculated? Read the full Feedwater Heating Is Really About Getting the Oxygen Out →
Boiler 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.