What is the difference between a combi boiler and a conventional boiler?
As well as taking care of your heating needs, combi boilers provide instant hot water. They have the advantage of freeing up space in a home, because there’s no need for a hot water cylinder (tank) like there is with a conventional boiler.
In most cases, heating water instantly is more energy-efficient than ‘stored’ hot water systems. However, the flow of hot water is slower than if it was coming from a cylinder, so a bath will take longer to run. Some combi boilers can in any case also heat water in a cylinder.
Modern boilers generally no longer have tanks in the loft to ‘pressurise’ the system through gravity. Instead they are sealed systems, and typically only require manual topping up from the mains water supply when the internal pressure has dropped (usually because of tiny leaks). This is a simple operation that takes a few seconds, and involves opening a valve on a pipe below the boiler.