Boiler Size Calculator
Size a steam boiler in BHP, BTU/hr and kW from steam demand, pressure and feedwater temperature.
Inputs
Results
Steam enthalpy h_g1176.8BTU/lb
Design steam flow6,000lb/hr
Boiler output5,932,604BTU/hr
Boiler horsepower177.2BHP
Boiler output (metric)1738.3kW
Fuel input required7,234,883BTU/hr
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Formula
Output BTU/hr = Steam × (h_g − h_f). BHP = Output ÷ 33,472. Input = Output ÷ η.
Worked example
5,000 lb/hr @ 100 psig, 220°F FW, 20% margin, 82% η → ~150 BHP, ~5.0 MMBTU/hr output.
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Frequently asked questions
What is 1 BHP?
1 Boiler Horsepower = 33,475 BTU/hr = 9.81 kW = 34.5 lb/hr of steam from and at 212°F.
Should I use gross or net feedwater temperature?
Use the feedwater temperature entering the boiler after the deaerator/economizer — that's what determines the enthalpy rise.
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