Method: Sensible heat recovered from returned condensate is estimated as: Q = ṁ × c_p × (T_condensate − T_makeup) using a water specific heat capacity of approximately 4.186 kJ/kg·K. The useful thermal energy recovered annually is: Useful Energy = Heat Recovery Rate × Operating Hours Because boiler fuel input is greater than useful heat output, avoided fuel energy is estimated as: Avoided Fuel Energy = Useful Energy ÷ Boiler Efficiency Annual cost savings are: Cost Savings = Avoided Fuel Energy × Fuel Energy Cost This calculator estimates only the sensible-heat benefit of returning hot condensate. Condensate recovery can also reduce makeup-water demand, water-treatment chemical consumption, blowdown requirement and wastewater discharge. Those benefits are not included automatically. Actual savings may differ because of flash steam losses, return-system heat loss, condensate contamination, pumping energy, varying return temperature and boiler operating conditions.