Boiler - Efficiency

Calculate boiler efficiency based on heat exported by the fluid relative to heat provided by the fuel. Supports both water heating and steam boiler calculations.

Boiler Efficiency Calculator

Boiler efficiency can be indicated by:

  • Combustion Efficiency - burner's ability to burn fuel
  • Thermal Efficiency - heat exchanger's effectiveness to transfer heat
  • Fuel to Fluid Efficiency - overall efficiency including losses

Formula

Boiler efficiency (%) = 100 × (Heat exported by fluid / Heat provided by fuel)

Heat Exported from the Boiler

For water heating:

  • q = (m/t) × cp × ΔT

For steam boilers:

  • q = (m/t) × h_e

Heat Provided by Fuel

Use either Gross or Net Calorific Value. Net calorific value ≈ Gross calorific value - 10%

Calculator

Inputs

Results

Heat Exported by Fluid-- kW
Boiler Efficiency-- %
Net Calorific Value Adjustment-- kW
Adjusted Efficiency (with calorific type)-- %
FuelUnitEnergy (Btu)
No. 1 OilGallon137400
No. 2 OilGallon139600
No. 3 OilGallon141800
No. 4 OilGallon145100
No. 5 OilGallon148800
No. 6 OilGallon152400
Natural Gascu. ft.950 - 1050
Propanecu. ft.2550
Butanecu. ft.3200