What is the difference between a vented and unvented cylinder?

If you've heard your plumber talking about vented and unvented cylinders, find out what they mean here.

The difference between these two types of cylinder is fairly straight forward.

A vented cylinder is one which is fed from a storage cistern above it (often located in the loft). The water from the cistern naturally flows down into the hot water cylinder below where it's heated, the water then flows back out of the cylinder through the taps when they are opened. The pressure of the water from a vented cylinder is typically very low, so we recommended that a pump or multiple pumps are installed to boost the pressure of the hot water for outlets requiring larger flow rates (showers, baths, basin taps etc).

An unvented cylinder is one which delivers mains pressure hot water. This removes the need for cisterns in the loft, as the water flows directly from the cold main into the cylinder where it is heated. The hot water then flows out of the hot taps when they are opened. Unvented cylinders are not suitable for properties with low flow rates and cannot be pumped with conventional shower pumps. Unvented cylinders require additional safety devices to be installed and require annual maintenance, whereas vented cylinders do not usually require any regular checks or adjustments.

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