Oil Boilers

An oil boiler works in a very similar way to a gas boiler. They comprise of several key components that include a pressure jet burner, a combustion chamber, a water jacket containing both a primary and secondary condensing heat exchanger and a flue system to safely remove the unwanted combustion gases that are produced by the boiler. Oil boilers also need their own fuel supply which will require an oil tank to be installed at the property. Oil boilers generally use kerosene as their primary fuel source but with an ever increasing demand for more sustainable home heating the introduction of biofuels such as HVO is well underway. The fuel used is ignited within the combustion chamber by the pressure jet burner. As the hot combustion gasses rise up through the heat exchangers, they heat the surrounding water within the boiler, and the heated water is then used to heat both the emitters, such as radiators and underfloor heating, and the domestic hot water within the property. Once the combustion gases have passed through the boiler they will enter and pass through the flue system and disperse safely outside of the property.

Oil boilers are categorised as either heat-only boilers, which provide heat into both the space heating and domestic hot water system and require a cylinder to supply the hot water to the property. Or a combination boiler (combi) which provides both heating and hot water direct from the appliance and do not require an additional cylinder. Both are usually available as both internal and external models.

Grant Vortex boilers are condensing oil-fired boilers – please click here to read more about how condensing boiler technology works.

The size of oil boiler that you will need will be determined by the heat loss of your property, the size of your home and your requirements for heating and hot water demand.

A combi, or combination boiler as it is also known, produces both heating and hot water from one compact appliance, removing the need for a separate hot water cylinder. Combi boilers are a popular choice for small-medium sized homes where space is at a premium.

Grant’s internal and external oil boilers have the same performance levels. An internal boiler is ideal when a direct boiler replacement is needed, with the new boiler being installed in the same location as the old boiler. When the location of the boiler is not changed, this can make for a straightforward installation with minimal alterations needed to elsewhere on the system. Sometimes, the size of a new boiler can be different to the old boiler – for example, if the new boiler is larger, alterations may need to be made to adjacent cupboards to accommodate the new boiler.

An external oil boiler is an ideal solution when space inside the property is at a premium or when it is more preferable to install the boiler outside rather than inside a kitchen, utility room or garage. Grant’s external boilers have the same performance levels as their equivalent internal boiler models so they are just as efficient. Grant’s external oil boilers also come with a factory flue which is included with the boiler. When it comes to installation, it is important that a level and sound base is in place for the boiler to be sited on top of, so a suitable foundation is needed when installing an external boiler. If an external boiler is replacing an internal boiler, your installer may also need alter the existing pipework leading to and from the boiler.

A condensing boiler has second (condensing) heat exchanger where the flue gases are cooled to below their dew point by the water returning from the heating system. This has the effect of condensing the water vapour present in the flue gases, and liberating the heat energy that would otherwise be lost to outside through the flue system.

In almost all applications you will not be able to use the existing flue. With condensing boilers there is a lower flue gas temp which leads to condensation/ moisture in the chimney/flue. The condensing boiler will need a Grant approved flue which is stainless steel and properly sealed at the joints to prevent leakage. All Grant external modules come with a factory fitted flue system.

HVO biofuel is not widely available to households in the UK but some fuel suppliers are sourcing and selling it so it is worth contacting local fuel suppliers to ask if they supply HVO biofuel for home heating. 

Grant oil boilers operating on kerosene, the most common heating oil in the UK, should be serviced annually. However, those operating on biofuel should be serviced twice a year.