Types of Boiler Burners


Their Function, and Everything You Need to Know

The burner is the so-called heart of a boiler and a vital part that allows your home to be heated and have hot water. Burners are complex parts that are made up of several individual components that allow it to function optimally. If your burner fails, you may not have to replace the whole thing, perhaps only some of the parts. In this article, we will discuss the different boiler burner types, what a burner is, how it works, and all of its components. We’ll also provide you with direct access to all the original burners for sale in the Suner store.

What is a boiler burner and how does it work?

A burner is defined as a device (in this case, one that is linked to a heating boiler and domestic hot water or DHW) that is specially designed to burn fuel in combination with an oxidizer, and in this way generate heat energy in the form of a flame that heats the water in the system. The size of a burner varies according to its function. There are small ones, such as those used in laboratory experiments, medium ones such as those contained in domestic boilers, and very large ones such as industrial burners.


As mentioned at the beginning of this article, the burner is one of the most important parts of a boiler. Within it, combustion takes place, meaning the chemical reaction between the fuel (diesel, gas, biomass) and the oxidizer (air, oxygen), which is a reaction producing energy release in the form of a flame. The flame heats the thermocarrier, which in this case, is water. This is what heats the inside of your home.

Technically speaking, the burner is responsible for creating the precise mixture of fuel and air to generate hot water and for sending this around your home, either for heating or hot water requirements. As one of the most important components of the boiler, the burner should be regularly inspected and it should, of course, be included in your boiler’s mandatory annual maintenance regime. If the burner is faulty, the boiler will simply not work.

So, how does a boiler burner work? Let’s take a look at it in the simplest way: Fuel travels from the fuel tank to the combustion chamber. When the fuel arrives, it is atomized and combined with air. Here, the electrodes start working by generating a high voltage electric arc between them. This ignites the fuel and air mixture and generates a controlled flame. The intensity of the flame depends on the setpoint temperature determined by the user. The heat generated by the burner increases the water temperature, which is then circulated through the heating circuit or supplied as domestic hot water.

What are the 3 types of boiler burners?

There are many different kinds of burners, and they are classified according to various criteria: according to their mechanism of producing the flame, according to the fule they use (fossil fuels derived from petroleum, fuels of natural origin, or biomass), according to the technology or equipment in which they’re used (heating, DHW, ovens, stoves, heaters, dryers, etc), and according to the context in which they’re used (domestic or industrial). For the purposes of this article, we’ll classify them only according to the fuel they use.


This is a general article. In it, we will mention and briefly describe the three most basic and conventional types of burners that exist for boilers (diesel, gas, and biomass). If you want to find out more, you’ll find links directing you to our articles that specifically discuss each type of burner in detail further on in the article and at the end.

The three kinds of burners we will discuss below are the so-called “mixed burners”. These are burners that combine the use of liquid fuel and gaseous fuel, normally diesel and gas. However, we will not discuss that in this article.

Diesel burners

Diesel burners are, as their name implies, burners that perform their function inside a boiler that uses diesel as fuel. Diesel is the most popular and commonly used liquid boiler fuel, and diesel burners are among the most best-selling and most widely used. In addition to diesel, other liquid fuels for burners are:

  • Fuel oil, a hydrocarbon derived from petroleum, is very polluting and the reason it’s been banned in so many countries.
  • Kerosene, a petroleum derivative and hydrocarbon mixture, is widely used in industry, not only as fuel for boilers, but also for other kinds of equipment.
  • Reused vegetable oil is a domestic oil that has already been used for cooking. It is reused as fuel for a boiler burner.

Biodiesel is nothing more than a combination of vegetable oil and diesel. It is much more eco-friendly and also much less polluting.


Diesel burners are characterized by their requirement for fuel to be pressurized before being combusted. Liquid fuels, such as diesel, don’t burn as easily as gaseous fuels. To achieve maximum diesel combustion efficiency, it should be pre-treated and pre-heated.

The function of the diesel pump is to pressurize the liquid diesel. This is done through a tube into a nozzle that has a very small hole, which causes it to atomize and then mix with the air (due to the Venturi Effect). A special fan will then introduce it into the boiler burner so that it ignites. The burner’s electrodes are responsible for ignition.

Gas burners

Gas burners for boilers function using some type of gaseous fuel, which can be either natural or artificial. In this context, “gas” is a generic word since various gaseous fuels can be used for boilers, such as propane and butane (both are hydrocarbons derived from petroleum), natural gas (fuel gasses obtained naturally in geological formations), and others, including hydrogen, lighting gas and water gas.


Gaseous fuels burn much more easily than liquid fuels. Unlike diesel burners, a gas burner’s function is not characterized by a requirement to pre-treat the fuel before pressurization. Obviously, it is not necessary to convert the fuel from liquid to gas as it already comes in a gaseous state.

In gas burners, fuel is mixed directly with air and then introduced into the boiler burner. It is also ignited via a spark. No safety devices are needed as the gas burns normally under ambient conditions.

Biomass or pellet burners

Biomass burners and boilers are considered eco-friendly sources for heating and providing hot water. “Biomass” is a generic term and refers to any natural element or residue that is used for boiler combustion, flame production, and heat. These elements or natural remains are called “biofuels”, whether they are pressed sawdust in the form of pellets, bioethanol, forest waste, fruit peels, pits, etc.


Due to their fuel peculiarity, biomass boilers and burners are only slightly different in terms of their structure and function from other kinds of boilers. Biomass boilers need a tank for storing biofuel. This must be located close to the boiler.

From the tank, the biofuel will be moved to the boiler via a continuous screw feeder device ar through suction. In order for this to happen, the biofuel must be stored at an angle of around 45°, which facilitates its entry into the boiler.

Biomass boilers work as follows. A biomass boiler’s combustion chamber is divided into 3 parts: the first zone (called a fixed or mobile grate, depending on the boiler size) is where the fuel is mixed with air. Through partial combustion, it becomes a gas and then a fuel gas. The second zone is where the flame is located and where additional air enters. In the third zone, combustion continues and CO is reduced.

Biomass burners have excellent advantages. Biofuel prices are fairly stable and biomass burners use natural materials (that are considered waste and widely available throughout the year) as fuel, help prevent fires, and their feeding and storage systems mean that they can have a fuel supply for weeks. Maintaining them is also very easy and, something quite important: biofuel is available at about half the price of other boiler fuel and produces much less polluting emissions into the environment.

Different components of a boiler burner

The parts making up a boiler burner depend on whether it is a diesel boiler burner, a gas boiler burner, or a biomass boiler burner. Furthermore, the parts can vary depending on whether it is a one or two-stage burner and the kind of fuel it uses.


Below we will take a general look at diesel and gas burner parts. To find out more about this topic, you can take a look at our specialized articles that cover each type of burner. We will leave links to these at the end of the article.

Diesel boiler burner parts

The parts making up diesel boiler burners are as follows: cover, programmer or control unit, base, photoresistor, photoresistor support, inspection window, clapper, electrode cable, burner fixing flange, insulating gasket, electrode, coil, pump, fitting, hose, turbine, flame tube, preheater/nozzle line, electrode holder and baffle.

Gas boiler burner parts

The parts making up a gas boiler burner are as follows: cover, motor, condenser, solenoid valve, turbine, connectors, ionization cable, ionization electrode, deflector, flame tube, fixing flange, electrode cable, transformer cable, transformer, programmer, or control unit, programmer base, pressure switch and flange joint.

This article wouldn’t be complete unless we mention another important part that, although is not part of the burner itself, is a vital part nonetheless. This part is the ramp, which is the part through which fuel is able to reach the burner. For more details about this, take a look at our articles on each burner type.

Fuel efficiency and boiler burners

A very important aspect of boiler burners is fuel efficiency. Fuel efficiency is defined as the intelligent and optimal use of fuel with regard to the least possible environmental impact. A boiler’s fuel efficiency is highly dependent on the efficiency of its burner.

In addition to the basic fuel efficiency parameters set out by the manufacturer, a boiler burner’s combustion can be manually regulated to affect fuel consumption. This is especially relevant in the so-called modulating burners and is best done by a qualified technician.

In order to produce the ideal combination of fuel and air in the burner, the quantity of air expelled and the optimal proportion of air and fuel should be considered. This is how you can achieve high combustion efficiency and excellent fuel efficiency. Of course, this also has a positive effect on your bank balance as it reduces your fuel costs without compromising on your comfort.

The gas-air mixture is expelled through holes that are located in the burner head. When the burner is used correctly, the flame can be adjusted according to your boiler’s specific needs. This is done by electronically controlling the valves and impulsion pumps. Boiler and burner manufacturers are increasingly looking for ways to achieve optimal fuel efficiency in their appliances. Apart from being competitive, it is a commitment to the planet, using clean energy and sustainable development.

Spare parts at Suner for 3 types of burners

By clicking on any of the following links, you will be able to browse all the burners for sale in the Suner store. These are all original parts, of the highest quality, and have been sourced from the manufacturer itself. We do not sell generic spare parts.

All 3 burner types

Click here to browse all our burners

All diesel burners

Click here to browse our diesel burners

All gas burners

Click here to browse our gas burners

All pellet burners

Click here to browse our biomass or pellet burners

The purchasing process is simple with Suner

Visit our store and see how simple the purchasing process is. You will always find the products you need (high quality original spare parts provided by your boiler’s manufacturer) and our website is very user-friendly and intuitive. Visit our store and see for yourself.

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