Oil Central Heating

Oil Central Heating

Modern oil-fired boilers can be very energy-efficient and manufacturers claim net seasonal operating efficiencies of up to 97%. As with gas boilers, the highest rated boilers will offer the greatest efficiency, and there are many 'A' rated models on the market.

An energy-efficient, oil-fired central heating system will have the same controls as a modern gas-fired system:

  • Room thermostat, ideally located in a living room, not the hallway.

  • Thermostatic radiator valves (TRVs) on all but one of the radiators.

  • Electronic 7-day timer with separately programmable hot water and room heating.

  • Cylinder thermostat on the hot water tank.

  • The boiler and thermostats wired in an interlock to prevent short-cycling when there is no demand for either hot water or room heating.

What type of oil-fired boiler should I install?

It has been mandatory since April 2007 to install condensing oil boilers to comply with Building Regulations. Modern oil-fired boilers can be highly efficient and there are now over 90 "A" rated models on the market. You can check boiler ratings on the SEDBUK website. For more information, you should speak to a reputable boiler manufacturer or installer.

Oil-fired combination boilers are also available, providing hot water on demand without the need for a hot water tank. However, it is fair to say that they are a bit slower to provide hot water than some gas combi boilers, and that they are not always recommended except for smaller households.

Oil boilers are available with both balanced flues (where the air for combustion is drawn in through a pipe concentric with the extract flue) and with open flues (where the air for combustion is drawn from the room in which the boiler is sited). Although Building Regulations permit both types of boiler to be located in domestic garages, we recommend that only balanced flue boilers are used in those areas. Most modern boilers use a pressure jet burner; although some vaporising burner machines are still available on the market, they may only be fitted into a limited number of locations.

What type of oil should I use?

Almost all UK domestic central heating systems use 28sec oil, which is sometimes known as kerosene. This fuel burns more cleanly than heavier oil products such as gasoil, which is also known as 35sec heating oil. 28sec oil can also be used in kitchen ranges such as AGA cookers.

As the sulphur content of oil has fallen, some domestic oil suppliers have added additional lubricants to kerosene to enable fuel to be pumped to the boiler more easily. This is not usually necessary for most systems, as modern pumps have been engineered to operate effectively with low-sulphur fuels, but if you are unsure if you would benefit from using such fuels, speak to your equipment supplier. 

Some smaller suppliers are looking at producing a bio-heating oil produced wholly from vegetable oils, similar to 100% biodiesel. At the moment, this is not widely available in the UK, but could provide a greener alternative to normal heating oil, especially if it uses waste vegetable oils as its feedstock. However, before using it in your system, we would always recommend checking with your boiler manufacturer to ensure that it is suitable, does not wax up in very cold weather and will not damage your burner or invalidate your boiler warranty. There have also been tests of a blend of biokerosine with traditional heating oil, known as B30K, as this is likely to work better in existing boilers and be less prone to waxing in very cold winters.

Is oil less friendly to the environment?

A modern, high-efficiency oil system can provide an environmentally acceptable alternative, especially for homes that are not connected to the gas main. As with all heating systems, regular servicing will help the boiler burn more cleanly and efficiently, and it is important to match all boilers to modern central heating controls.

Many people are concerned by the threat of global climate change, and are keen to reduce their personal emissions of carbon dioxide (CO2), the main gas contributing to this effect. Official figures from the UK's Department for the Environment, Farming and Rural Affairs (Defra) indicate a carbon content for domestic heating oil (kerosene) of 0.245kgCO2 per kWh, compared to figures of 0.214kgCO2 per kWh for LPG and 0.184kgCO2 per kWh for gas. However, these figures are for gross calorific values, and a typical "A" rated condensing oil boiler achieving 95% efficiency would be responsible for around 5% more CO2 in use. Equivalent gas condensing boilers are a little less efficient, reducing the carbon penalty for oil systems to less than 10% compared to LPG and around 20% for mains gas.

If you are particularly keen to minimise carbon emissions, you may wish to consider supplementing an oil central heating system with a modern wood-burning or pellet stove, using sustainable wood fuel.

How do I install an oil central heating system?

Although there is no legal requirement for oil boilers to be installed by a specially trained person, we strongly recommend that all servicing and installations are carried out by people registered with Ofted, the Oil-Fired Technical Association.

Is there anything else that I should know about oil central heating?

We also recommend that all oil-fired systems are fitted with an automatic shut-off in the event of fire. This will prevent a fire spreading to the external oil tank. Most tanks are now made of plastic and so are easy to maintain. There are quite complex regulations on where they may be sited and your local council's Building Control Officer should be able to advise you on these. All boiler installations are required to conform to Part J of the Building Regulations, and oil-fired systems should also meet British Standard BS 5410.

Are there greener alternatives to oil?

If you're concerned about climate change and the use of fossil fuels, there are a number of alternatives to consider. If you are connected to the gas network, then this is the easiest route to go, even though it is still using a finite fossil fuel with emissions that are only about 20% better than oil. If you would prefer to use lower carbon renewable technologies, then there are two main alternatives: biomass and heat pumps. As oil is a relatively high carbon (and costly) fuel, it also makes sense to limit your demand for it by making sure that your home is as energy efficient (internal link) as possible. Also, most oil boilers work very well with solar water heating, which can provide most of your domestic hot water in the daylight hours during the spring, summer and autumn months.