With this tool, you can calculate the heat loss from the chimney and the combustion efficiency from the flue gas temperature and oxygen (O₂) value you measure with a flue gas analyzer. Valid for natural gas, fuel oil, diesel and LPG.
Formula (Siegert)
qA = (tA − tL) × (A2 ÷ (21 − O₂) + B)
tA: flue gas temperature, tL: combustion air temperature, O₂: oxygen (%) in dry flue gas. Coefficients: natural gas A2 = 0.66, B = 0.009; fuel oil and diesel A2 = 0.68, B = 0.007; LPG A2 = 0.63, B = 0.008. Excess air ratio λ = 21 ÷ (21 − O₂).
Example
In a boiler burning natural gas, if the flue gas is 180 °C, the air is 20 °C and O₂ is 3%, the flue gas loss is 7.31%, the combustion efficiency is 92.69%, and the excess air is 16.7%.