Can be powered by gas or electric
A combi boiler (or combination boiler) is the most common type of boiler in the UK. A combi boiler heats water directly from your mains, providing instant hot water from the tap, they’re energy-efficient and cost-effective to run. A combi boiler is incredibly compact and doesn’t require cold water storage or hot water cylinder and is often located in your kitchen - but can also be in the garage, a bedroom or cupboard.
A combi boiler is perfect for small to medium homes with one bathroom.
No cold water tank in the loft
A system boiler is very similar to a combi but it requires an additional hot water storage cylinder. The system boiler will initially heat the mains water, whilst the hot water cylinder will store and maintain it - so you'll always have instant hot water on hand. This is a space-saving option to a regular boiler but will take up cupboard space with the added hot water cylinder.
It's ideal for homes with more than one bathroom as it can deliver hot water to multiple taps and they’re also very economical to run.
Also known as a heat-only boiler
A regular boiler is similar to a system boiler, but it requires a cold water storage tank (often found in the loft) as well as a hot water cylinder. A regular boiler uses the cold water stored in the loft to heat up, it will then transport the hot water to the cylinder which keeps your water at a lovely hot temperature. The regular boiler was the most common type of central heating system.
A regular boiler is ideal for larger homes with more than one bathroom and low water pressure.
Located behind a fireplace
Often referred to as BBU (Back Boiler Unit), this system provides both central heating and hot water. This will be located behind a fireplace which could be powered by gas, electric or fuel. This is likely to be an older system, so if you choose to convert to a gas combi system then you’re likely to benefit from energy efficiencies.