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Differences Between The Vented and Unvented Hot Water Cylinder

Some technological advents for the household these days have a certain back to the future quality about them. While many items have transitioned to electricity, the hot water cylinder has proven to be an incredibly versatile and adaptable product that can cater to a variety of requirements and circumstances.

Whether it be powered by a wetback system, a solar panel, a heat pump, a gas bottle or something else entirely, there is a litany of options on the table for home owners who are looking to secure a consistent stream of warm water for their bathing and cleaning needs on a daily basis.

The choice will then come down to a choice between one of two types of the hot water cylinder – the vented vs. the unvented. Questions will often arise both to the initiated and uninitiated when it comes down to the best style for the surrounding environment.

Here we will examine the essential differences between each, offering a framework for the home owner to make their decision.


For the vented hot water cylinder, a tank is stored in a central location whereby a series of pipes line throughout the premises to connect the taps in the sink, bathroom and occasionally the radiators if required. When compared to the unvented system, one that simply bypasses this process to connect the cylinder to the main, it is far more cost efficient. The unvented operation can require an air bubble or an extra safety feature to cope with the excess water, something that drives up the price for the consumer.


So what does gravity have to do with a hot water cylinder exactly? Well this field speaks to the proximity in which the item is being stored as a cold tank will see a difference in pressure depending on the location of the cylinder. The greater the height between the cold water tank and the tap where the water is being released, the greater the source of gravity is driving the pressure.

This creates a tangible difference between an upstairs and a downstairs bathroom, a scenario that is not entirely fair the premises as a whole and far from ideal. The unvented option derives from the main, ensuring that this is a hot water cylinder source that is reliable more times than not. Without any tank, there is no stress and anxiety as to where this would be placed.

Tank Space

Actually finding a space for a hot water cylinder can be quite the task depending on the nature of the home or office. If space is of a premium whereby the location is of a shared unit profile or it is closed off, then this forces the owner to look for a spot inside the premises. Ideally there will be a loft or a basement or somewhere where something of this capacity can be safely stored whereby an overflow of water is not going to cause too much concern. More times than not a preexisting vented system will be kept in place and unless there is the space to play with, an unvented option will be installed. This bypasses the need to fight for space without a tank altogether.


When you are shopping for a hot water cylinder that will service your hot water needs, run a full diagnostic of the premises and see what budget you have to play with. A vented hot water cylinder is cheaper in the short-term, but an unvented system has proven to be incredibly efficient and perhaps more of a long-term investment when considering storage space and general maintenance, especially when combined with a solar hot water heating system.