What is a combi boiler?

A combi boiler, also known as a combination boiler, is a water heating and a central heating unit, combined into one. Due to the small nature of combi boilers, they are best suited for smaller houses.

An oil combi boiler may seem similar to a gas powered combi boiler, but there are a few big differences. For example, an oil combi boiler has instant access to water as it is directly connected to the water mains supply. In addition to this, an oil boiler requires an oil tank to store the oil in.

Advantages of an oil combi boiler

There are multiple benefits to having an oil combi boiler, including:
-Instant water access: As the boiler is connected to the water mains, it has instant access to water to heat up.
-Efficiency: Oil has a better return on every unit of energy used than gas, meaning an oil boiler is more efficient as it has a reduced amount of waste products. Newer models of oil boilers are estimated to be 92 – 95% efficient.
-Accessibility: For those who do not have access to the grid, particularly in rural areas, having an oil combi boiler is a great alternative.
-Size: Oil combi boilers are generally smaller than most types of boilers, meaning they take up less space in your kitchen or utility room.
Build-ups – Calcium, dirt and scaling build-ups are less likely to happen with an oil combi boiler as no hot water is stored.

Disadvantages of an oil combi boiler

Like all boilers, oil combi boilers also have some drawbacks:
-Oil prices: Oil prices fluctuate a lot, meaning there might be a period of time where oil combi owners are paying a lot more for the same amount of oil.
-Timing: Despite having instant water access, oil combi boilers provide hot water slower than gas boilers.
-Breaking down: If an oil combi boiler breaks down, you will lose both hot water and heating.
-Water pressure: The water pressure may decrease if multiple appliances are using the hot water at the same time.

Oil Combi Boiler Models

There are a variety of oil combi boiler models, which will perfectly fit your home and your needs. A few models we recommend are:
Worcester Bosch Greenstar Heatslave II
Grant VortexBlue
Firebird Envirogreen Combi
Warmflow Agentis Combi


In conclusion, oil combi boilers are efficient boilers that are perfectly suited for small houses, especially for those who do not have access to the grid. Despite having to pay for oil and the potential decrease in water pressure for multiple appliances, oil boilers are estimated to be 92 – 95% efficient bringing costs down and have instant water access when required.

If you have any questions or would like a boiler installed, please contact us on 01274 317169 or at info@bradfordboilercompany.co.uk.