In Denmark a litre of heating oil now costs DKK 22.25. According to the Danish broadcaster TV 2 Øst, that is more than at the 2022 peak, when a litre cost around DKK 20, and roughly 35 per cent more than before the war in Iran, when the price was DKK 16.40. A homeowner in Sallerup near Vordingborg says he uses 1,500–1,600 litres a season. He has not yet filled his tank and is waiting for prices to fall.
The good news is that there is a lot to gain from the oil boiler itself. With 1,550 litres a year at DKK 22.25 a litre, using 10 per cent less is worth around DKK 3,400 a year.
1. Get an annual service
An annual service is the most important tip. The service engineer cleans the boiler, replaces wear parts and measures the flue gas, so the burner can be set to the right mix of air and oil. A boiler that is not properly adjusted can use more oil than necessary for years without you noticing.
2. Replace the nozzle
The nozzle atomises the oil so it burns cleanly. Over time it wears, the atomisation gets worse, soot builds up and consumption rises. The nozzle is a cheap wear part that is normally replaced at the annual service. If the boiler has become oversized for the house, a smaller nozzle can also give better combustion.
3. Keep the boiler free of soot
Soot on the boiler’s heating surfaces acts as insulation and stops heat from passing from the flame to the water. The heat goes up the chimney instead. Soot is also a sign that the burner needs servicing.
4. Replace the oil filter
A clogged filter makes life hard for the pump and the nozzle. The oil filter is cheap and quick to replace, and it protects the rest of the burner.
5. Insulate the boiler, hot water cylinder and pipes
An uninsulated boiler and bare pipes in a cold boiler room give off heat around the clock. Insulating the boiler, hot water cylinder and pipes in unheated rooms is one of the cheapest improvements.
6. Lower the boiler temperature
Many boilers run hotter than they need to. A lower boiler temperature, ideally controlled by the outdoor temperature, reduces heat loss from the boiler and pipes. The hot water cylinder must still be kept hot enough to prevent legionella. Ask your service engineer what your system can handle.
7. Bleed and balance the radiators
Air in the radiators means they do not heat up all the way, so people turn up the boiler instead. Bleed the radiators every autumn and use the thermostatic valves to keep the right temperature in each room.
8. Check the chimney draught
Too much draught pulls heat out through the chimney, and too little gives poor combustion. A draught stabiliser can keep the draught steady. The service engineer can measure the draught at the service.
9. Consider a new burner
An old burner can rarely be adjusted as precisely as a new one. Modern oil burners burn more cleanly and are easier to set up. If the boiler is in good condition, a new burner can be a good investment, also with a view to HVO later on.
10. Consider a hybrid solution
The biggest saving comes from letting a heat pump do most of the work. In a hybrid solution the heat pump covers the base load, and the oil boiler becomes the backup on the coldest days. We have written about how a hybrid solution can be a gentle first step in the green transition.
Spare parts at Arne Nielsen A/S
Arne Nielsen A/S has supplied parts for oil boilers since 1969. We stock nozzles, filters, pumps and other spare parts for burners from Oilon, Riello, Weishaupt and Intercal, among others. Write to us at info@arnenielsen.com with a photo of the rating plate, and we will find the right parts.
Source: TV 2 Øst (in Danish): Thomas’ oliefyr er tomt – venter på et mirakel (October 2026)
Photo: Screenshot, TV2 Øst.
