Understanding oil heating
Everything you need to know about oil heating
You will still find them in many existing buildings: oil-fired boilers. We offer an overview of the advantages of this heating system, the possible uses and combination options as well as the associated costs.
Oil heating still popular in old buildings
Around a quarter of all buildings in Germany produce their heat with oil. In new buildings, however, oil heating systems are hardly found at all. Modern oil heating systems are also very efficient thanks to condensing technology.
They are an important option in old buildings where alternatives are unsuitable - if no gas connection is available for gas heating, for instance. If you wish to combine your oil heating with renewable energies to create a hybrid system, you will not receive a subsidy, but you will still benefit from a reliable heating system.
Existing buildings
Another advantage of oil heating systems: they can theoretically work in any building. However, oil heating demonstrates its true strengths in the modernisation of old buildings, where it proves very flexible. As mentioned above, you don’t need a gas connection and can typically use the existing heating pipe system without impairing your old building’s period appearance.
This assumes that you have sufficient space in the cellar for the oil tank. Modern technology also allows for an underground tank in the garden for storing your heating oil.
New buildings
Heating systems based on renewable energy make perfect sense in new buildings to contribute to climate protection. In buildings with good insulation, heat pumps provide the necessary heat in an environmentally friendly manner, making them particularly popular. Hybrid gas heating or a combination of various renewable energy sources are also options here.
According to the Buildings Energy Act (GEG), heating exclusively with oil is not permitted in new buildings. A combination of oil with renewable energies, such as solar thermal technology, is generally feasible. However, most builders today choose one of the other options listed.
Whether it makes sense to replace an old oil boiler with a modern oil condensing boiler is a question best left to an expert. Contact a heating installer in your area to find out more.
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How does modern oil condensing technology work?
If you use a modern oil heating system, you don’t have to forgo efficiency. Modern condensing technology ensures that the heating system makes optimal use of the energy content of the heating oil.
However, the radiators in the building must be designed for a flow temperature in the heating circuit that does not exceed 60°C. Only then does the condensing technology have the desired effect.
Heating systems with a condensing boiler are so efficient because they are able to reduce the heating losses of the system that arise due to hot exhaust gases. Older low-temperature boilers release exhaust gases at temperatures from 140 to 200°C. This wastes valuable heat.
In contrast, condensing boilers can extract the heat from these exhaust gases, cooling them down to 50°C. Watch the video below to learn more about how condensing technology works.
Operating costs
The costs of operating an oil system are not much higher than those of gas heating. You must also plan for the annual maintenance of your oil heating system.
Tip: With a maintenance contract, you don’t have to stress over this every year, and you may even save on costs.
Every five to seven years, you should have your oil tank cleaned by a specialised company, which you can expect to cost €500 or more, depending on the design of the tank.
The price of oil
The biggest factor in the ongoing heating costs, however, is the price of the fuel. Everyone knows from the petrol pump that the oil price fluctuates widely. But despite all prophecies of doom, it has not skyrocketed to unprecedented highs in some time.
Nevertheless, no one knows exactly what this means for the future. On one hand, the CO₂ pricing in Germany, which has been in effect since 2021, has moderately increased the price of heating oil. However, the efforts to fight climate change could cause oil demand to fall globally. One conceivable result could be a moderate oil price in the future.
With a new oil condensing system, you can heat very efficiently. The new system will save money by using much less fuel. As a result, it will hit breakeven within just a few years.
If you also use renewable energies in a hybrid system, you not only support climate protection, you are also investing in a heating technology that will result in low heating costs over the long term while making you less dependent on oil price fluctuations as well.
Frequently asked questions about oil heating
The installation of oil heating as the sole heating system is prohibited as of 2026. However, legislators have allowed certain exceptions. For example, an oil boiler combined with solar thermal or a heat pump is still permitted. Exceptions also apply if
- there is neither a gas supply
- nor district heating nearby
- or if an environmentally friendly alternative would not be efficient in your house.
Oil heating systems are subject to mandatory replacement according to the Building Energy Act (GEG) if they are constant temperature boilers that are more than 30 years old. Exceptions to this replacement requirement apply to buildings with a maximum of two residential units where the homeowner has personally lived since 1 February 2002. It is still possible to install a new oil heating system until 2026. After this, it will only be allowed in exceptional cases.
The typical oil tank for a single-family home holds between 1,000 and 3,000 litres of fuel. Larger tanks are possible in principle, but are subject to stricter safety requirements starting at 5,000 litres and up.
The switch from an old heating system to an oil condensing boiler is generally not difficult. Renovation of the exhaust gas line is one important measure to remember. This is done by having a heating technician install a plastic pipe into the existing chimney.
As with petrol for your car, there are also various qualities of heating oil. For the sake of the environment, you should always used low-sulphur heating oil. Premium heating oil also contains certain additives that guarantee the quality of the fuel for longer storage. Bio-heating oil contains a portion of renewable energy derived from regenerative materials and can be used in all oil heating systems without problems as long as it does not contain more than 5% biofuel.
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