Combi vs System vs Regular Boilers

A combi boiler provides heating and hot water without a separate cylinder. This can save space and works well in many smaller homes or properties with moderate hot water demand.

Performance depends on the incoming mains water supply. Homes with several bathrooms or simultaneous hot water use may be better served by stored hot water rather than simply choosing a higher-output combi.

A system boiler works with a hot water cylinder and is often suited to family homes where more than one outlet may be used at the same time. Many of the main heating components are contained within the boiler, allowing a comparatively straightforward system layout.

Cylinder capacity and recovery time need to match the household. An unvented cylinder may provide strong mains-pressure hot water where the incoming supply and property are suitable.

Regular, heat-only or conventional boilers are commonly found on traditional systems with a cylinder and separate feed tanks. Retaining this arrangement can sometimes avoid unnecessary disruption in larger or older properties.

Changing a regular boiler to a combi is possible in many homes, but existing pipework, water pressure, bathroom demand and the condition of the wider system must be assessed first.

The right choice depends on available space, water pressure, the number of bathrooms, simultaneous demand, existing pipework and future plans for the property. APS surveys these factors rather than recommending one boiler type for every home.