When it comes to heating, there are a few technical terms that need to be explained. You can find everything you need to know here. In alphabetical order.
Combustion air contains up to 21 percent oxygen, which is essential for combustion. 78 percent of the air is nitrogen. About 10 cubic metres of Combustion air is required for the complete combustion of 1 cubic metre of gas or 1 litre of heating oil.