Cleaver-Brooks - Complete Boiler Room Solutions

Correctly Matching Burner to Boiler in a Retrofit

Tip Sheet: July 2015

Key Facts

  • To ensure high heat transfer, a burner’s flame shape and length must be matched to the furnace or combustion chamber
  • A burner’s combustion characteristics have to integrate well acoustically with the boiler, which has its own resonant frequency
  • Make sure the new burner is easy to inspect and maintain on a regular basis

To properly execute a burner retrofit, a burner’s flame shape and length, or flame envelope, must be matched to the furnace or combustion chamber. This ensures a high heat transfer without impinging on the furnace walls in a manner that could be detrimental to the furnace or convection pass materials.

Another key factor to consider when doing a burner retrofit is combustion noise or combustion vibration, often referred to as “combustion rumble.” Every boiler assembly has its own resonant frequency, so it is important to ensure that the burner’s combustion characteristics integrate well acoustically with the boiler and its acoustical nature.

Since most burners are not custom-designed for each application, the burner must be flexible in design so that during the commissioning process, any undesirable combustion noise can be “tuned out” for smooth operation throughout the firing range.  

In addition, the burner should be constructed of castings or heavy-gage materials and “spinnings” that afford strength to the burner surfaces, thereby reducing unwanted high-frequency vibrations. Otherwise, at certain loads, the whole package may vibrate causing unacceptable noise and vibration as well as undue wear and tear on the system. 

Burners constructed of light-gage sheet metals and large flimsy surfaces may be less expensive up front, but are noisier for the environment. These less expensive products have a much shorter life expectancy and generally become more expensive to the owner over time.

Lastly, ensure that the new burner is easy to inspect and maintain on a regular basis. An operator should not have to pull the burner off the vessel, or worse, crawl through the furnace to get to the burner, particularly for the larger burner sizes.

Remember, even with all the latest technology incorporated into a state-of-the-art burner, regular maintenance is still necessary to ensure optimal fuel-air ratio throughout a boiler’s firing range and equipment life. Properly servicing a boiler system on a consistent basis will maintain its efficiency and lower fuel costs for years to come.  

To learn how two facilities executed burner retrofits for improved efficiency and reduced emissions, watch the Burner Retrofitting – Real-Life Stories webinar. To talk with a Cleaver-Brooks representative about retrofitting the boiler system in your facility, visit