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Unvented Cylinder Installations

What is an unvented hot water system?

An unvented hot water system is essentially a hot water cylinder which is pressurised to the mains water pressure, meaning that you get a high flow of hot water no matter where you are in your home. The cold water is fed into the hot water cylinder directly from the mains water supply, with no requirement for a cold water tank. It is the mains water pressure which forces the hot water out of the top of the cylinder and then delivered to the taps.


What are the benefits of installing an unvented hot water system?

If you are struggling with pressure in your shower then an unvented hot water system will solve this without having to install a noisy pump. It is also an ideal system if you have a busy family home and want to be able to run multiple taps at once. It will support two or more bathrooms and you will feel very little change in water pressure when you have multiple taps running, unlike conventional systems where you can often be left with a trickle of water.


Unvented hot water systems are also energy efficient as the cylinder is insulated with polyurethane foam, meaning that once the water is heated it stays hot for longer, so there is less of a need to reheat the system. They can be heated by gas, electric immersion heaters or solar power.


What about servicing?

Similar to your boiler, you should have your unvented hot water system serviced annually. All unvented hot water systems have an expansion vessel to allow for the increase in volume of water as it heats up. Some unvented cylinders have an internal air bubble which acts as the expansion vessel. Over time, the expansion vessel or air bubble can become flat and therefore an annual service is important to recharge them.

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