Unvented hot water cylinders are used to store water that has been delivered directly from the mains water supply, and then warm it using either electrical heating elements or with heat from a boiler.
This then creates high pressure hot water supplies that are able to deliver high flow rates of hot water to your appliances. The cylinders store water under relatively high pressures, typically in the region of 2 to 3 bar (20 to 30 metres head), and as such can supply water to outlets at high level, such as in a loft space, and at similar pressures to the mains cold water supply.
What are the benefits?
Due to the increased pressures of water, you are assured to benefit from better quality showers, without the need for any pumps. What’s more, with both hot and cold water services fed from the mains, there is no more need for a cold water storage tank, keeping loft spaces clear, and pipework to a minimum. Usually, an unvented hot water cylinder will produce between 18-25 litres of hot water per minute which is much greater than any what combination boiler can give. What’s more this will also remain consistent throughout the flow even when another tap is opened.