Unvented Systems
How an Unvented Cylinder Works:
An unvented cylinder is supplied by the incoming main. When you open your tap, pressurised cold water enters into the unvented hot water tank from the bottom, which gets heated before coming out from the top outlet, resulting in hot water coming to your taps.
What is an Unvented hot water system?
- An unvented hot water system takes cold water supply directly from the incoming water main.
- They are not gravity fed by a tank in the loft.
- They can be direct or indirect.
If your home or business has been fitted with an unvented heating system, it’s advisable that you get it serviced every year to ensure it keeps running effectively and working as it should. Unvented heating systems operate without a cold water tank, and instead, cold water from the mains is fed directly to the sealed hot water cylinder.
Thanks to the fact that your unvented heating system is operated at mains pressure, you benefit from a heating system with better flow rates. The result? Showers and baths that operate better, and the ability to use more than one hot tap at once without a reduction in performance.
Unvented systems offer a fast response from the moment you turn your hot tap on to the time it takes for the water to become hot. This also helps to ensure running costs are economical and kept as low as possible. Another benefit to having an unvented system is the fact that noise levels are reduced as – unlike a conventional open-vented system – there is no water storage cistern to be filled with cold water. Furthermore, because unvented systems don’t need gravity to pump water around your property, the unvented cylinder isn’t restricted to a specific location. That means this style of heating system is particularly useful if you don’t have a loft space.
So if you’re thinking of having an unvented heating system installed in your home or business, or you need to get your existing system serviced, our skilled UK Gas Heating engineers will be happy to assist. Installation of an unvented heating system is quicker than conventional systems so disruption is kept to a minimum. Give us a call today on 0800 917 3370 to arrange a system service or find out whether an unvented heating system could be the right choice for you.
Advantages:
- Pressure is much higher on all outlets.
- No loft tanks which reduce risk of contamination and legionnaires
- No pipes in the loft so no frozen pipe risk.
- Very high heat recovery rate after use. Typical warm-up time 15-20 minutes.
Disadvantages:
- The hot water pressure will only be as good as your incoming main, however this is fine for most people.
- You cannot fit shower pumps on mains water supplies. However you shouldn’t really need to.
- When feeding multiple outlets the pressure can drop. This also applies to vented systems. On unvented systems.

Our Greenstore hot water cylinder range perfectly complements our Greenstar system or regular boilers.
Hot water is supplied at mains pressure for powerful showers and fast bath filling. Greenstore cylinders offer high performance, fast re-heat times and significant energy savings over traditional cylinders.
Our cylinders come in 7 sizes from 90 to 300 litres.

Our Greenstore hot water solar cylinders are specifically designed to work with our Greenskies solar water panels. With all the same benefits as our unvented range, they enable you to add solar water heating panels to your system at a later date without having to replace your cylinder.
Hot water is supplied at mains pressure for powerful showers and fast bath filling. Greenstore cylinders offer high performance, fast re-heat times and significant energy savings over traditional cylinders. Our solar compatible cylinders come in 5 sizes from 150 to 300 litres.
To book a free no obligation quote please contact us.