Very often shortened to combi boiler.

These boilers supply both heating and hot water all from within one unit. No hot water is stored in a cylinder unlike a conventional or unvented system. Instead, the combi boiler provides instant hot water on demand.

The combi boiler is the most popular and fastest selling type of boiler on the market as it saves on a lot space and provides high pressure hot water. You do not need any tanks in the loft, a cylinder in the airing cupboard or a pump to boost the water pressure.