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Vented water cylinder

A vented hot water cylinder is normally associated with a conventional heating system and is fed from a cold water storage tank rather than through a mains fed pipe as with an unvented system. This is by far the most common type of cylinder although the actual design is getting on a bit in today's standards of combination boilers and unvented heating.


Vented cylinder - how it works


vented cylinder

Vented cylinder

This picture shows an indirect cylinder fed via the cold water storage tank. Water is heated by a primary heat exchanger within the vessel supplied by your boiler.


On this example there is also a provision for a immersion heater as back up.


The cold water is supplied to the vessel via a cold water storage tank, often located in the loft space directly above the hot water cylinder. A vent pipe runs from the top of the hot water cylinder and into the lid of the cold water tank above. This venting allows for the expansion of water in the cylinder via air bubbles and steam, and ensures the water is safely condensed to the cold water tank.


A standard vented system relies on gravity to supply hot water to the taps and shower(s), this means that the hot water cylinder must be located below the cold water storage tank, to generate the required 'head' of water pressure to adequately feed all the radiators.

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What we can do for you


We can offer maintenance, repairs and also installation for new or replacement conventional vented cylinders. We can also offer advice and installation options if you are looking to upgrade your old gravity fed system into a pressurised, unvented or combination system. All of our work is guaranteed and carried out to our usual high standard.


Some possible upgrades:


convert to combination boiler


Upgrade to a combination boiler

If you require an upgrade to a combination boiler you can do away with your water cylinder entirely. This means you can save a lot of space and also achieve 'hot water on tap'.



upgrade to unvented cylinder


Upgrade to an unvented cylinder

By upgrading your conventional vented cylinder into a unvented cylinder you can experience mains pressure hot water and also remove the cold water storage tank in your loft, again a great space saver.


replace worn cylinder


Replace your old or worn vented cylinder

If you would rather keep your system the same (possibly a gravity fed system) but you need to replace your cylinder we can offer options and carry out the necessary work.


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Important information

If you do have an immersion heater it is highly advisable to get your unit checked, especially if the unit is a good few years old. If your immersion heater has not been replaced in the last 2 years - has it got an over heat trip?


If it does not have an over heat trip - get it replaced by one that has by a competent person, please do not rely only on the advise "hot water coming out of cold taps" as your cold water may not come from the storage tank.


If you would like further advise regarding your immersion heater or cylinder please do not hesitate to contact us.