Annual tune-ups can be performed by boiler operating personnel or engineering consulting firms. Money spent on a boiler tune-up is one of the best investments you can make. Reducing Excess Air Under perfect combustion conditions, there is a so-called theoretical amount of air which will completely burn a given amount of fuel with no excess air remaining. In practice, more air than the theoretical amount must be supplied to the burner to ensure complete burning of the fuel. A further reduction in excess air causes rapid increases in carbon monoxide and other combustibles which result in a rapid deterioration in efficiency.
Excess air is the extra air supplied to the burner beyond the air required for complete combustion.
Excess air is supplied to the burner to provide a safety factor above the actual air required for combustion. A boiler firing without sufficient air, or fuel rich, is operating in a potentially dangerous condition. However, if there is too much air, heat energy from combustion is used to warm the excess cold air, which reduces boiler efficiency. Reducing excess air is one of the most effective boiler improvement techniques. The lower the exhaust gas, the less heat loss.