How an Unvented Hot Water Cylinder Operates


Two hot water cylinders are commonly installed in UK homes. These systems include the newer pressurised unvented hot water cylinder and the older vented hot water cylinder. The unvented hot water cylinder was made legal in 1986. From that time, it has grown steadily in popularity.

Better Flow Rates

Because unvented cylinders are operating at mains pressure, they provide better flow rates, which leads to a better bath or shower performance. When you use this type of tank, you do not need to include a cold water tank in the loft. Vented systems, on the other hand, require this addition. As a result, space is freed up and any potential freezing issues during the long, cold winter are removed as well.

A Less Noisy Cylinder

Also, because you don’t need to rely on gravity to move the hot water throughout the home, an unvented cylinder can be installed just about anywhere in a property. According to East Sussex plumbers, an unvented cylinder is less noisy too. That is because there is no filling of cold water in the storage cistern. As a result, the system is sealed, and the water is not at any risk of contamination.

A Pressurised System

In an unvented system, a mechanism must be added that permits the expansion of the water so that it can get warm at a safe pressure. Two methods are used for this purpose. The first one is a bubble top unit, which employs an internal air bubble that is trapped at the top of the cylinder during installation.

One Disadvantage

The other type of expansion unit uses an expansion vessel in order to store the hot water. The main disadvantage of using this type of cylinder has to do with water access. Because the cylinder depends on mains pressure, you cannot access water if the mains water is shut off. As such, this unit counts on other implements in order to run properly.


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