Boiler & Furnace Calculators
Boiler Blowdown Calculator
Calculate the boiler blowdown percentage needed to keep dissolved solids in boiler water below the safe maximum, based on feedwater and boiler water TDS.
Boiler Combustion Calculator
Calculate the total combustion air a boiler burner needs, including excess air margin, from fuel flow and stoichiometric air ratio.
Boiler Fuel Requirement Calculator
Calculate the fuel flow rate needed to generate a target steam output at a given boiler efficiency and fuel heating value.
Boiler Steam Generation Calculator
Calculate boiler steam generation rate in kg/hr from fuel input, boiler efficiency, and enthalpy gain.
Furnace Heat Load Calculator
Calculate the heat load a furnace must supply to raise a mass flow through a specified temperature rise.
Furnace Residence Time Calculator
Calculate how long combustion gases remain in a furnace chamber given furnace volume and gas flow rate.
Furnace Volume Calculator
Calculate furnace or combustion chamber volume from length, width, and height for sizing and residence time calculations.
Steam Boiler Efficiency Calculator
Calculate overall steam boiler efficiency from steam flow, enthalpy gain, fuel flow, and fuel heating value.
The Equipment-Level Math Behind Boilers and Furnaces
Boiler and furnace design combines combustion math with equipment-specific concerns — how much water needs to be blown down to control dissolved solids, how much steam a given fuel input can generate, and how long fuel actually spends in a furnace's combustion zone. Eight calculators here cover that equipment-level sizing and operating math.
Popular Boiler & Furnace Calculators
Eight tools span steam generation, blowdown, and furnace sizing:
- Boiler Steam Generation Calculator — calculates steam output from fuel input, boiler efficiency, and feedwater conditions.
- Boiler Blowdown Calculator — calculates the blowdown rate needed to control dissolved solids concentration in boiler water.
- Boiler Fuel Requirement Calculator — calculates fuel needed to produce a target steam or hot water output.
- Furnace Heat Load Calculator — estimates total heat input required for a furnace process.
- Furnace Residence Time Calculator — calculates how long combustion gases remain in a furnace's active combustion zone.
Why Blowdown Is a Balancing Act, Not a Fixed Number
Boiler blowdown removes concentrated dissolved solids from boiler water before they scale or foam, but every gallon blown down also carries away the heat energy already put into that water — too little blowdown risks scale and carryover, while too much wastes treated, heated water. This is exactly why blowdown rate is calculated from actual feedwater and boiler water solids concentration rather than a flat percentage, since water quality varies enough between sites that a one-size-fits-all blowdown rate would either under-protect or over-waste depending on the source water.
Frequently Asked Questions
Does higher blowdown always mean safer boiler operation?
Not necessarily beyond the point needed to control solids — excess blowdown wastes treated water and fuel-derived heat without adding meaningful protection once solids are already within safe limits.
Explore More
Need the burner feeding this boiler sized too? See the Burner Calculators, or check overall efficiency in the Heat & Energy Calculators.