Boiler Tuning: Striking the Perfect Air/Fuel Mixture

Boiler Tuning: Striking the Perfect Air/Fuel Mixture

You need three things to make a combustion: fuel, oxygen and ignition. If you've ever made a potato cannon, you understand this lesson well. Too much air in the combustion chamber and your spud doesn’t launch with the pizzaz you expect; too much fuel and, well, bad things can happen (boom). Side note: I’ve found that Aqua Net hairspray makes the best fuel source. To achieve the best launch, you have to strike the perfect balance between fuel and air in the chamber.

The same is also true with steam boilers. In order to achieve optimum efficiency, your boiler has to be tuned with the proper air/fuel mixture.Too much O2 in your boiler results in the boiler running inefficiently. Too much fuel in your boiler and catastrophic failure can occur.


Boiler tuning is necessary to maintain efficiency as well as to ensure reliability and safety. Plant technicians will often look through the peephole on their boiler, see a flame, and make the mistake of thinking their boiler is running smoothly. Unfortunately, a majority of the time, this is not the case at all. Not all flames are created equal. Seeing a nice blue flame doesn’t mean you’re getting the best production out of your boiler. Boilers must be sized to meet maximum potential demands, but did you know that the average boiler operates at 30-45% of its capacity?

When looking at boiler O2 output, you really want to keep it at 3%. When O2 numbers climb above 3%, you have excess air and your boiler loses efficiencies. Excess air causes:

• Flame quenching

• Furnace cooling

• Reduced efficiency


Seasonal tune-up. Tuning the burner during the spring and again in the fall is recommended because of the dramatic air temperature and density changes that occur during these seasons.

Tune the boiler when it is hot. A cold boiler will throw off actual operating O2 and CO readings.

Parallel positioning systems with integrated flame management. This allows old technologies to be as efficient as they can be.

Replacing linkage arms with servo motors on the fuel metering valve and combustion air damper.

Periodically monitor flue gas composition and tune your boilers to maintain excess air at optimum levels. Consider online monitoring of flue gas oxygen level to quickly identify energy loss trends that can provide early warning of control failures and allow data to drive your decision making.

Utilizing a pre-mix technology achieves an 85% fuel/air premix, making fuel/air adjustments easier. Premix technologies also allow your boiler to achieve and maintain a 3% O2 output which greatly improves turndown ratios – meaning you can make steam more immediately while realizing significant fuel savings.

WARE’s team of boiler experts are highly skilled at evaluating a boiler’s condition and making sound recommendations on how to improve efficiencies and realize cost savings. WARE offers efficiency testing programs as well as controls and instrumentation evaluations to ensure that you are getting the most out of your boiler, day in and day out.

For a more detailed explanation of boiler tuning and how to get the most from your boiler, watch this video. WARE’s experts explain how to get the most out of your combustion and what you can do to avoid flame quenching. They also offer valuable tips on how to obtain better heat transfer and making your maintenance more efficient.

If you have more questions, call WARE today -- 1-800-228-8861.

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