The adjustment of an oil burner

The adjustment of an oil burner

Talking about the adjustment of an oil burner, we mean making the right setting so the burner produce the best burning effect it cans, consuming the less oil. This technics should be done by an oil burner technician, a man that has the special equipment needed to measure the burn process.

Facilities in operation

Existing heating plants of homes, offices, hotels, hospitals, or other similar uses that use diesel oil, there is exhaust heat loss, volume by volume of carbon dioxide (CO2). The maximum permissible value of the soot indicator and the exhaust gas temperature are defined as follows:

Buildings that have fixed combustion hotspots with a total thermal power greater than or equal to 400,000 Kcal / h:

  • Maximum permissible value of heat losses with the exhaust gases: 20%
  • Minimum permissible value of the carbon dioxide (CO2) content of the exhaust gases: 10%
  • Maximum permissible value of the soot index: 1 on the Bacharach scale
  • Minimum permissible exhaust gas temperature: 180 ° C.

For buildings with fixed combustion sources with a total thermal power of less than 400,000 Kcal / h:

  • Maximum permissible value of heat losses with the exhaust gases: 20%
  • Minimum permissible value of the carbon dioxide (CO2) content of the exhaust gases: 9%
  • Maximum permissible value of the soot index: 2 on the Bacharach scale
  • Minimum permissible exhaust gas temperature: 180 ° C.

Oil burner adjustment in new installations

For a new oil burner installations that use diesel oil and is going to be installed in new or old buildings:

  • Maximum allowable value of heat losses with exhaust gases 15%
  • Minimum allowable soot index value from 0-1 on the Bacharach scale.

Exhaust gas temperature setting

The thermometer for measuring the exhaust gas temperature should be placed at a distance of about 20 cm from the boiler outlet. The measurement must start when the boiler water temperature reaches 80 ° C. If the exhaust gas temperature is higher than 180 ° C, then change the injector by installing a smaller supply.

If the temperature is lower than the amount of the 180 °C, we make use of bigger injectors. We can make the oil pressure less or more if we are allowed to do so. Of course, if this is a small increase or decrease in the exhaust gas temperature

It is understood that the combustion surfaces of the boiler are clean, because smoke 2 mm thick on the surface of the boiler, increases the flue gas temperature by about 40 ° C.

CO2 regulation

The regulation of the CO2 content of the exhaust gases is done by reducing or increasing the air supply from the oil burner and mixing it with the oil. Thus, if we reduce the fan air supply we have an increase of% CO2 and if the burner operates with excess air then this content is low.

With a little air, however, we have an increase in CO2 but also an increase in the soot index. So before adjusting the CO2 content of the exhaust gas, we must adjust the burner so that we have the allowable soot value. If we achieve this and the CO2 content is low, then we try to achieve the right mix of fuel and air by moving the diffuser forward or backward. CO2 is measured with special instruments.

Air adjustment

The measurement of the soot index in the exhaust gases is done with instruments. High soot content in the exhaust gas means a small amount of air in relation to the combustible material. Adjust the burner air supply so that the soot indicator value is within the allowable limits.

Heat losses

We should know the temperature of the exhaust gases and the CO2 content. Then with the help of a scale, we find the heat loss with the exhaust gases. The lower the temperature of the exhaust gases and the higher their CO2 content, the lower this loss.

Annual Degree of Performance

Perhaps the most important element in a central heating installation is the annual degree of efficiency. This, together with the right choice of boiler power, is a prerequisite for fuel economy. The degree of combustion efficiency or the degree of efficiency of the boiler, do not give a complete picture of the size of fuel consumption. To have a complete picture, we need to know the annual efficiency of the installation.

Annual efficiency

Annual efficiency is the energy (heat) produced by the boiler, minus the exhaust gas losses, the thermal losses of the boiler and the shutdown losses of the installation. That is, the heat we have for space heating and domestic hot water.

  • Exhaust gas losses are the heat we lose from the chimney
  • Boiler losses, is the heat emitted by the boiler to the environment, during its operation
  • Interruption losses are the heat that the boiler loses to the environment and the chimney, while the burner is off
  • Combustion efficiency, is the combustion heat (100%) minus exhaust losses

Ideally, we should have an annual efficiency of 100%, which means that all the energy produced was converted into useful energy. Of course, this is practically impossible because we already have 10% losses from the hot exhaust gases (180 degrees Celsius), which come out of the chimney.

We also have losses from the boiler, the piping, etc. In the best case, the efficiency of the whole installation can be around 86%. Even this value is rarely achieved and only when the installation is new.

High degree of efficiency

In order to have a high degree of efficiency, the followitg are required:

  • Boiler and piping strongly insulated
  • The boiler should not be on standby, to avoid interruption and operation losses
  • High degree of combustion efficiency (over 90%)
  • Small in size boiler, with low water content and according to requirements (not much larger than required)


We should take a careful look at the possible points of loss in a central heating system.  then one will find that it is not at all unlikely that an official survey revealed an average annual efficiency of less than 40%. This means that 60% of the fuel we buy is lost.

Our goal is to get as close as possible to 90%. We can achieve this by buying a modern economical boiler, and a modern oil burner. But have in mind that modern installation alone is not enough. It needs modern perception and knowledge for its proper operation. For example, from a single window that remains slightly open, we have within 10 hours losses, which correspond to about 3.5 liters of oil.

We hope we make our best effort to give you the knownledge that is required for this type of work. Note that in order to have the better results, especially in fuel economy, this is a maintenance that should be done by a technician. This is the right man, having the necessary equipment to perform this kind of tasks.