Combi boilers provide central heating and hot water but because they only consist of one individual unit, the central heating system does not need a separate boiler installed in the loft or airing cupboard, hence the name ‘combi boiler’ unlike heat only boilers, a combi boiler does not store hot water itself but instead draws on water running through the mains, which is why the unit does not need a separate boiler situated elsewhere in the house. When you need honest,.