Combustion efficiency is the calculation / measurement, in percentage, of how well your equipment is burning a specific fuel. Complete combustion efficiency (100%) would extract all the energy available in the fuel. However, 100% combustion efficiency is not realistically achievable. Various combustion processes produce combustion efficiencies from 0% to 95+%. Combustion efficiency calculations assume complete fuel combustion and are based on three factors:
If your calculation shows that your equipment is losing 25% of the heating value of the fuel through stack losses, your equipment is running at 75% efficiency.
| Combustion Process | Efficiency Range |
|---|---|
| Residential Fireplace | 10-30% |
| Space Heater | 50-82% |
| Commercial Gas Boiler | 70-82% |
| Residential Gas Furnace with Atmospheric Burner “Low Efficiency” | 70-82% |
| Oil Burner Heating System | 73-85% |
| Induced Draft Furnace “Medium Efficiency” | 74-82% |
| Boiler with Gas-powered Burner | 75-83% |
| Condensing Furnace (Gas & Oil) “High Efficiency” | 75-90+% |
One only needs to measure gas concentration (O2 or CO2) and temperature to determine combustion efficiency. Although other gases (NOx, CO, SO2) do not significantly effect combustion efficiency, these gases are an important safety and environmental concerns.
