Greenvision Energy

Electric Water Cylinder 

Unvented pressurised water cylinders

Reduce your energy bills, never run out of hot water and increase your water pressure. Pressurised hot-water cylinders give invigorating showers and baths can be filled much more quickly. 

They also allow you to be in control of your water temperatures to exact degrees via smart devices. 

Why upgrade your old water cylinder to a unvented pressured unvented water cylinder?

Installing a low energy consumption hot water cylinder can significantly reduce your energy bill, improve bath filling times, and increase shower pressure. Control your water temperatures to the exact degree with smart controls and 24/7 timers. Heating hot water can account for over 50% of your energy consumption so choosing the right hot water cylinder can save you £100s per year. We offer a range of low-energy consumption electric hot water cylinders for your or your business.

Our hot water cylinders are incredibly well insulated and have an extremely accurate thermostat which means less temperature variation. Less temperature variation means less energy used. They are also designed to take advantage of economy 7 tariffs & renewable energy sources.

Unvented water cylinders were introduced in the UK market in 1986, but have since grown rapidly in popularity. In an unvented system, there is no cold-water tank, instead, the sealed hot water cylinder is fed directly by the cold water mains. They offer much better flow rates, meaning your shower and bath performance should be higher.

The other major benefit is that you don’t need to maintain a cold water tank in the loft (which vented systems require). This is good news since not only does it free up space, but it also removes the potential freezing issue during our long cold winter periods.

The benefits of unvented water cylinders

Increased Water Pressure

Invigorating showers and quick filling baths are achieved with pressed hot water cylinders. We can remodel your airing cupboard to create more space.

Lower Energy Bills

Pressure Cylinders have superior insulation and extremely accurate thermostat which means less temperature variation. Less temperature variation means less energy and cheaper bills.

Never Run Out Of Hot Water

Lay back and relax and never run out of hot water again. Improve bath filling times and increase shower pressures. Now is the time to install a pressured hot water cylinder and start saving energy

How do unvented water cylinders work?

An unvented system has no cold water tank, but a sealed hot water cylinder which is fed directly by the cold water mains. An unvented cylinder is kept pressurised from the incoming water supply and is heated by either an immersion heater (a direct model) or by an external heat source such as a boiler or wet solar system (an indirect model).

An unvented cylinder will have pipework connected to it that distributes the hot water to multiple outlets around the house. As soon as a tap or shower is used, the pressure of the incoming cold water drives the hot water in the cylinder towards the open outlet at mains pressure.

Unvented systems are ‘sealed’, so they use an expansion vessel to allow for the expansion of water in the system as it heats up. The expansion vessel is sited either next to or within the boiler or cylinder and can accommodate the increase in pressure by up to 4.5 bar.

More Reasons To Buy Unvented Water Cylinders

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Space Saving - A pressured hot water cylinder doesn’t require a feeder tank in the loft which frees up valuable space in your property. This makes it easier move your cylinder in to your loft, garage etc

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Reduced Noise Levels - No more waking up to cold water filling up the water storage cistern. The pressured system completely silent and sealed, so not at risk of contamination and won’t freeze in winter months.

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Much faster heat up time.

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Slimline unvented cylinders available for narrow airing cupboards and horizontal options available for lofts.

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Super insulation meaning less energy needed to maintain heat, reducing your energy bills

Hassle Free Installation

Invigorating showers and quick filling baths are achieved with pressed hot water cylinders. Be in control of your water temperatures to the exact degree. We can remodel your airing cupboard to create more space.

Sit back & relax with our award-winning installation service

Start Saving Energy
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Frequently Asked Questions About Pressured Unvented Hot Water Cylinders

Yes, Greenvision has a range of cylinders that you can control via a smart app.

With this type of cylinder there is no need for a storage tank as water comes straight into the cylinder via the water mains. Mains pressure means gravity feed does not apply, so the cylinder (minus storage tank) can be positioned virtually anywhere at any height, and you get a much more powerful flow than from a vented system. Also, you don’t have to worry about water freezing in a header tank during very cold snaps.

In an unvented installation the system won’t suffer contamination because it is sealed and bypasses areas were impurities could get into the water. With regards to water expansion, the unvented cylinder has either a permanent air bubble infused at the top of the cylinder, or a fitted expansion vessel.

Both vented and unvented hot water cylinders can use either direct or indirect heating systems. With the indirect method the cylinder is heated by a gas boiler or other external source. Hot water passes from the heat source through a copper coil built into the cylinder. In this case it’s a good idea to fit a reserve emersion heater in case of boiler breakdown, so you still have hot water.

The direct method involves one or two heating elements inside the cylinder that heat the water directly. Using the two element option can be very cost effective because it is specifically designed to be used with the Economy 7 tariff – one element for peak day time use and one for off peak where the water is heated cheaply at night and used when needed.

In an unvented system there is no cold water tank – instead a sealed hot water cylinder is fed directly by the cold water mains. An unvented cylinder is kept under pressure from incoming water supply and is heated by either immersion heaters (a direct model) or by a heat source located outside the vessel such as a boiler or wet solar system (an indirect model).

Vented hot water cylindersThis type of water cylinder needs a water storage (header) tank to store water piped in from the mains. The tank is usually installed in the loft (or in the highest point in the property) and the system relies on gravity to create a reasonable pressure for the hot water to circulate throughout the property.

Vented cylinders are easier to install than unvented, but they do need a vent pipe to deal with water expansion issues. Households most likely to benefit from vented water cylinders would be properties with an electric shower only, no bath and just one or two people living there.

You should only have an unvented hot water system fitted and serviced by a qualified person holding a current G3 Unvented Qualification. All installations of unvented hot water cylinders have to be notified to Building Control as required by Building Regulations. If your installer is a member of a Competent Persons Scheme, this will happen automatically and you will receive a Building Regulation Compliance certificate.

A hot water cylinder should last for more than 20 years if fitted correctly and to the highest standard. However, the life expectancy of a hot water cylinder can be shortened by water leaks.

They can be installed in almost any location – the garage, upstairs, downstairs, loft or even in a basement. An unvented hot water cylinder needs a safety discharge pipe. Therefore in some basement locations, a sump and pump may be required.

You should consider replacing your hot water cylinder if it is leaking water, but drying at the same time. Leaking water can get worse over time and cause damage. Small leaks can be hard to detect so you should always check for any damp patches surrounding a hot water cylinder. Consult your plumber or call Greenvision Energy if you are unsure about whether your hot water cylinder has a slow water leak.

Copper corrosion is the cause of the green on your hot water cylinder. The corroding copper is most likely the result of an acid attack of flux or there is water surrounding the area. Copper corrosion may also be the result of a high amount of moisture in the air.

  • If you get constant leaks or breakdowns it could work out cheaper to replace rather than to keep repairing. 
  • Your new boiler will be much more energy efficient and could pay for itself quite quickly. 
  • If you have a big family or use lots of water a new professionally fitted boiler will be sized correctly for your needs, which may not be the case at present. 
  • If you have an old boiler with a red jacket you will be paying higher energy bills than you need to. You would be better off upgrading to a new cylinder and better tariff. The off peak tariff in conjunction with the two element cylinder could save you lots of money. 
  • If your water pressure is low and it takes forever to run a bath or the shower is just a dribble, a new unvented hot water cylinder will give amazing improvements.

What people think

Based on 33 reviews
Isobel Gleave
Isobel Gleave
I'm very pleased that I went ahead and replaced my old storage heaters with the new Dimplex ones. The whole process went smoothly and efficiently and Greenvision were very helpful at all stages and didn't rush me. Apart from working better than the old ones they also look smart, as does the new bedroom panel heaters. The installers did a brilliant job and didn't leave a trace.
Gemma Rogers
Gemma Rogers
Quality service for installation of a new Dimplex Quantum storage heater, Rointe electric towel rail, updated fuse box and all associated. The service provided by Greenvision went beyond all expectations. Everyone was extremely helpful and friendly. Stuart and Paul provided professional advice based on what would be best for me. The virtual survey option was ideal, so we could discuss options and get a quote straight away, which meant from contacting Greenvision to installation was only a couple of weeks! Amanda was great in keeping me up to date about the installation and arrangements. On the day, Dan arrived exactly when expected and fitted everything perfectly, it's made such a difference. Thank you to everyone at Greenvision. Very impressed and wouldn't hesitate to recommend!
Peter Graystone
Peter Graystone
I found Greenvision very pleasant to work with. The explanation of the product, and the survey to check it was suitable for my home were both excellent. The engineer was courteous and efficient, although I would have loved it if he had vacuumed before he left. I'm very pleased on the whole.
Purchase and installation of Dimplex Quantum Storage Heaters. Very professional from start to finish. In contact throughout. Answered questions and were friendly and helpful. Fitters were very efficient and even brought a hoover to clear up afterwards! They explained everything regarding usage. Very polite and professional from start to finish. Would recommend.
ann munro
ann munro
I instigated my business with Greenvision 6 weeks or so ago. The staff at Greenvision were informative, considerate of my needs and quick to answer any queries. Adjustments to my advantage were made after a survey which have proved to be most adequate. The installation occurred on 16th. January. The engineers were on time, efficient and considerate, clearing up and tidying up as they proceeded. They took time to make sure I understood the basics of operating my heaters. I will certainly recommend Greenvision where and when I can. So quick.
Sarah Moyer
Sarah Moyer
I used Greenvision for purchase and installation of 2 electrical high heat retention heaters for use with Economy 7. Everyone at Greenvision was friendly and helpful. Although based in Nottingham they facilitated installers for me in London. The whole process was seamless, quick and efficient. I would certainly recommend this company.
Carol G
Carol G
We purchased new Dimplex storage heaters through Greenvision. I was totally impressed by their level of knowledge, advice, customer service and ability to organise an efficient installation of these products at our property in North Wales. Highly recommended!
Lucy Reynolds
Lucy Reynolds
Very pleased with the installation of a Quantum Dimplex storage heater. Clearly explained at all stages and electrician who installed it was excellent.
Ray W
Ray W
6 Dimplex Quantum storage heaters installed to replace old heaters and associated modifications carried out to wiring in meter cupboard. Friendly helpful installers and very professional job. Highly recommended.
Brian Lomas
Brian Lomas
Supplied and fitted 3 Dimplex Quantum storage heaters. Used Greenvision because other residents in our retirement flats recommended them from their experience. They were right to do so as our experience was the same. From start to finish our experience was seamless and efficient ,polite, friendly are words that come to mind. The team that arrived with us on installation day was Nathan/Paul and Luker. All three were cleanly dressed, polite and friendly but courteous. They were very competent indeed and represented an excellent image of the Company. J B and L Lomas SANDBACH

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Electric Water Cylinder