What is an unvented cylinder?
Unvented hot water cylinders store water supplied directly from the mains water supply, and heat it using either electrical heating elements or with heat from a boiler.
This provides high pressure hot water supplies capable of feeding outlets with high flow rates of hot water. 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.
The increased pressures also make for better quality showers, without the need for pumps. 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.