In order to make steam, a boiler needs fire. That fire has to be carefully controlled to get the maximum amount of heat out of every fuel dollar. That task falls to the burners, the heroes of combustion that keep the fuel and air in the proper mixture to preserve efficiency and provide steady, even heat.
WHAT IT IS
A burner is more than just a nozzle that sprays fuel. It’s a carefully shaped, precisely tuned piece of equipment that is responsible for combining air and fuel at the proper ratio to minimize unburned fuel in the exhaust gases and ensure every cubic inch of fuel burns properly. The burner is composed of several parts that help it do its job.
The diffuser mixes the air and fuel together, while helping to shape the flame for maximum surface area. By shaping the flame, the heat is more evenly distributed on the surface of the pressure vessel, which not only ensures even heating, but also minimizes hot spots that can cause metal stress.
The nozzle, found in oil-burning burners, helps atomize the oil into fine mist that mixes with air more evenly to create steady, even combustion.
Swirl vanes create turbulence. While turbulence sounds like a negative, it’s actually crucial to proper air/fuel mixing. By creating turbulence in the air, the swirl vanes end up creating more surface area for the air and fuel to interact before they are ignited, which promotes more thorough burning and more efficient fuel usage.
Mounting Flanges are the points at which the burner is bolted to the boiler. They make sure the burner is positioned at the correct angle and orientation for ideal combustion.
THE GAS TRAIN
The boiler’s gas train includes every component that supplies fuel to the boiler to help it do its job. The gas train starts with the utility fuel line, passes through a pressure regulator, and culminates at the burner where the action happens. The pressure regulator is there to make sure the fuel is supplied at the manufacturer’s specified volume, and pressure so the burner can do its job without running too rich or too lean.
OIL BURNERS
For boilers that burn oil, there is no gas train. Instead, there is an oil train that serves the same purpose of supplying fuel to the burners. The oil train includes a pump to supply the oil under pressure, so that when it reaches the burner it can spray under pressure to atomize properly and mix with the air for proper combustion.
AIR SUPPLY
Burners need air to mix with fuel. To supply that air, boilers use one or more fans to force air under pressure into the burner. This forced-air induction not only keeps the burner supplied with enough air to do its job, but it also helps create the draft that draws combustion byproducts out of the fire side and into the stack.
To make sure the air is supplied in the proper quantity, the air system includes an air pressure switch that monitors the pressure flowing into the burner. If more air is needed, the forced induction fans increase in speed, and/or dampers open to allow more air to flow. If less air is needed, the reverse happens.
IGNITORS
Fuel and air don’t just spontaneously ignite when mixed. It takes an ignitor to start the combustion process. Ignitors create the initial spark or heat for combustion in one of three ways.
Direct Spark Ignition ignitors arc electricity across a gap to start the fuel and air burning.
Pilot Ignitors use a smaller flame that runs constantly to ignite the fuel and air mixture.
Hot Surface Ignitors use a ceramic element that is electrically heated until it glows red-hot, hot enough to cause the fuel and air mixture to ignite.
CONTROL SYSTEM
Today’s modern burners are actually part of a sophisticated system that monitors combustion to make sure everything runs safely and smoothly. Contemporary Burner Management Systems use a series of sensors to preserve ideal performance and monitor the flame during startup with safety interlocks that confirm proper operation. Incidentally, WARE has always been a big fan of AUTOFLAME systems because of their innovation, reliability, and efficiency.
Every modern control system includes a Flame Detector that confirms the burner is lit when it’s supposed to be. These systems are crucial for safe operation; if a flame isn’t detected when it’s supposed to be, the system shuts down the fuel supply so that excess fuel doesn’t collect and create a hazardous situation.
Contemporary control systems also include modulating motors that adjust fuel and air, keeping the burner running efficiently based on demand. Rather than running at full capacity or zero capacity, modulation allows the flame to be adjusted to different levels so that the boiler can maintain steam production based on how much steam is required. In times of high demand, the modulating system will supply more fuel to create a bigger, hotter flame to make more steam. Then, when demand subsides, the modulating control system will lower the fuel supply to keep the steam at a lower sustained output.
TUNED UP
To get the absolute best efficiency out of a boiler burner, the burner must be professionally tuned. During the tuning process, a combustion analyzer is used to test the combustion under different conditions to make sure the burner is running properly, consuming fuel properly, and not emitting any excess carbon monoxide. Tuning is an important aspect of any boiler’s maintenance routine, and should be done at least annually to ensure proper combustion.
WARE’S BURNER LINEUP
WARE proudly carries burners from the best manufacturers, including Limpsfield, Power Flame, Faber, Maxon, and Victory Energy. Each of these companies was chosen for the WARE lineup due to their uncompromising quality and durability.
LEARN THE BURN
If you’d like to learn more about combustion from real industry experts, consider taking a class at WARE’s Boiler University. Specifically, Boiler U 302 “Principles of Combustion” can be a goldmine of information for anyone wanting to learn more about how boilers turn flame into steam. This three-day class includes not only an introduction to combustion itself, but also focuses on important aspects of burner operation including gas trains, linkages, and gas pressure regulators. The class also includes a hands-on lab that gives participants an opportunity to see combustion tuning up close.
If you suspect your burners aren’t running at their best, or if you see excess soot in your fire side, the professionals at WARE are standing by to help. We’ll be glad to tune your combustion system to make sure you’re getting the most out of every fuel dollar. If you need maintenance or service, we’re here to help with them as well. And if you need parts or supplies, be sure to check out our online BoilerWAREhouse e-commerce site, the largest in the nation, with shipping times of two days or less to most of the country. Whatever you need, just let us know.
Combustion Systems FAQ
What does a boiler burner do?
A boiler burner combines air and fuel in precise ratios to create controlled combustion, producing the heat needed to generate steam. It’s a critical component in any boiler system.
What are the main parts of a boiler burner?
Key components include the diffuser, nozzle (for oil burners), swirl vanes, and mounting flange. Together, they ensure efficient fuel-air mixing and flame shaping for even heating.
What is a gas train in a boiler system?
The gas train includes the fuel supply components leading to the burner, such as regulators and shut-off valves. It ensures the right amount of fuel reaches the burner at the correct pressure.
How is air supplied to a boiler burner?
Air is typically delivered by forced induction fans. Air pressure switches and dampers help regulate the air supply to ensure the correct fuel-air ratio for efficient combustion.
What are the types of burner ignitors?
Common ignitors include direct spark, pilot ignitors, and hot surface ignitors. Each creates the initial heat or spark required to ignite the fuel-air mixture.
Why is combustion control important in a boiler?
Combustion control systems like AUTOFLAME ensure burners operate efficiently and safely by monitoring flame quality and adjusting fuel/air inputs based on demand.
How often should boiler burners be tuned?
Burners should be professionally tuned at least once a year to optimize fuel efficiency, reduce emissions, and prevent safety hazards.
What are signs my boiler burner needs maintenance or tuning?
Excess soot, uneven flame patterns, or decreased efficiency may indicate poor combustion. A professional tune-up can restore optimal performance.
Where can I learn more about boiler combustion systems?
WARE’s Boiler University offers in-depth training, including the 3-day Boiler U 302: Principles of Combustion course with hands-on lab experience.
Which burner brands does WARE carry?
WARE provides high-quality burners from leading manufacturers like Power Flame, Limpsfield, Faber, Maxon, and Victory Energy.