Unvented hot water cylinders were only made legal in the UK in 1986, but have since grown rapidly in popularity. Megaflo cylinders are an example of unvented cylinders and the current market leader in the UK. An unvented hot water cylinder is fed directly using the cold mains water pressure, delivering hot water to showers and taps at mains pressure. In an unvented system, there is no cold-water tank, instead, the sealed hot water cylinder is fed directly by the cold water mains offering much better flow rates, meaning your shower and bath performance should be higher. The other major benefit of unvented systems is that you don’t need to maintain a cold water tank in the loft, thereby freeing up space and removing potential freezing issues during cold winter periods. Other advantages of installing an unvented system include reduced noise in the system since there is no cold-water filling of a water storage tank.