Question

how to find that excess air is supplied in furnace

Answer 1

excess air calculate:::


Excess Air = 100 x (20.9%) / (20.9% -O2m%) - 100%
Where O2 m% = The measured value of oxygen in the exhaust.

Examples:

When O2m% = 0% Then excess air = 0
When O2m% = 5% Then: excess air = 100 x (20.9%) / (20.9%-5%) - 100%
excess air = 100 x (20.9%) / (15.9%) - 100%
excess air = 100 x (1.31) - 100%

excess air = 31%