The Energy Saving Trust says that boilers are still the most common form of heating appliance – it is estimated that they account for 60% of what we spend a year on energy bills. An unvented hot water cylinder can work with a system or heat only boiler, but how do they work?
With systems that incorporate unvented hot water cylinders, the water comes straight from the mains supply rather than a cold water storage tank. This results in high flow rates and fast-running baths and taps. They can store and simultaneously distribute hot water to different outlets at mains pressure with flow rates in excess of 22 litres per minute.
There are two types of unvented cylinder – direct and indirect. Direct heated cylinders are heated by electric immersion heaters, while indirect heated cylinders have a primary hot water coil and are heated by the same boiler
that provides central heating.
Flexible solution
Unvented cylinders offer flexibility in terms of installation. Because they have no need for a cold water storage tank, householders actually gain loft space rather than lose it should they choose to have their cylinder installed somewhere other than the loft.
As they do not have to be sited above water outlets – such as baths and showers – they can be installed almost anywhere within a property – for example, airing cupboards, utility rooms, kitchens, cellars, garages or indeed lofts. With no need to fill a cold water storage cistern, the householder also benefits from reduced noise and there is no longer any risk of burst pipes in roof spaces.
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