In your natural gas furnace or boiler, excess combustion air helps the furnace or boiler completely oxidize the fuel, and prevents vapor build-up. But excess combustion air also produces more nitrogen oxide (NOx), an air pollutant. Try these tips to reducing the volume of combustion air that travels from your boiler to your heat exchanger.
1. Staged Combustion
Low NOx burners usually use a staged combustion process. The oxygen level in the first stage of burning is reduced, and in the second stage, the combustion heat level is reduced. Staged combustion involves taking 1 burner out of service, or injecting air in from a secondary source over the flame burner.
2. Cyclonic Burner
The swirling flame pattern of a cyclonic burner can reduce combustion air volume by more effectively mixing gas and air, and improving the recirculation of combustion gas. The flame temperature is lowered and less NOx is formed.
3. Ceramic Fiber Burner
Installing a ceramic fiber burner allows the fuel and air to be premixed before entering the combustion chamber. The ceramic material helps cool the fuel-air mixture, reducing NOx emissions to low levels.
4. Flue Gas Recirculation
In this process some of the combustion gases are recirculated into the boiler's windbox. To refit a boiler for flue gas recirculation, add a gas fan, dampers and air ducts.