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22 Manchester Square, Marylebone, London W1U 3PT Call: 07970 655 040

Unvented Cylinders

Our WRAS approved heating engineers install, service and maintain unvented hot water cylinders and calorifiers for domestic and commercial properties.

  • Faster, more efficient service with high performance ‘coil-in-coil’ heat exchanger
  • Minimised mixing of cold and hot water
  • Improved performance, even at 1 bar
  • Increased flow rate by up to 35% via water inlet controls
  • Reduced carbon footprint – CFC free insulation for maximum heat retention
  • Reduced noise – quieter mains pressure system
  • Consistent water pressure, no peaks and troughs
  • Consistent, high performance showering and fast-filling baths – wherever you are in the home
  • Faster and tidier installation
  • Comes complete with a mains water isolating valve
  • No need for an annual inspection as there is no sacrificial anode
  • Durable Duplex stainless steel interior


Is an Unvented Cylinder safe?

Unvented cylinders are perfectly safe when fitted and annually serviced by licensed operatives. If a problem does occur with the cylinder the numerous safety controls will keep the cylinder in a basic non-operating state until a fitter can diagnose and repair the issue.

Is an Unvented Cylinder economical?

A correctly fitted unvented Cylinder, although more expensive to have installed will save heating times, gas costs, emissions and money. An Efficiency of nearly 100% can be achieved as well as modern zoning techniques, high water flow rates, safe temperature blending and even electricity bills due to less pumping of water.

Are you gas safe registered?

Yes all of our engineers are fully qualified and Gas Safe registered. The Gas Safe register is the official list of gas engineers who are qualified to work safely and legally on heating appliances. Follow this link to find out more about Gas Safe or feel free to call us and we’ll answer your queries.

Does a boiler need to have regular services?

We recommend that you have your boiler serviced each year. This will ensure that it is working at maximum performance and safety. Here at Priory Gas Heating we offer tailored service packages to give you peace of mind that your boiler is serviced to high standards at an affordable price.

How long will it take to service a boiler?

It will usually take our Gas Safe engineers approximately an hour to service your boiler. This estimated time will of course vary depending on individual circumstances. You will only ever be charged the agreed service fee quoted to you by our team, prior to your boiler being serviced.

Can I Use Megaflow With Solar Heating?

Yes. Megatech Solar domestic hot water cylinders based on Megaflow HE (unvented) technology, have been specifically designed for solar applications.

Are Unvented Hot Water Systems Energy Efficient?

Yes. Unvented hot water systems exceed the Energy Efficiency Partnership’s ‘Best Practice’ for recovery times and insulation levels. This means the system heats up quickly and is more efficient at retaining the water temperature.

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Our Process


Discuss your heating system’s current efficiency with one of our heating & experts. We carry out a free survey, provide you with a no obligation quotation and advise you on the best heating system appropriate for your property size, heating requirements and budget.


With exceptional value-for-money servicing, we promise that you pay exactly the amount you have seen us quoting on day one. No nasty hidden charges or uncanny surprises after installation, as we want to keep our consumers happy, safe, and warm!


Our registered Gas Safe plumbing and heating engineers are fully qualified and resourceful, and trained to install, design, repair and service every requirement of your home heating systems.

Our Clients Highly Recommend Our Plumbers

Priory Gas Heating has provided us with excellent service whilst installing our boiler. They were courteous and cleaned up the packaging after the work was complete. We also received the guarantee and Gas Safety certificate. Very pleased with their workmanship…

Peter Wallace
Rating : 5

During the instillation they were discrete, professional and reliable. No empty or broken promises. They were able to tailor their working hours, to suit the needs of the school, often working in the evening to avoid classroom disruption. During every…

Ian Kendal
Rating : 5

Richard has been carrying out work for myself and our residential committee at our Mayfair apartment complex for the last 4 years. During this time we have found Richard and his team at Priory a real gem to work with,…

Lady Montagu of Beaulieu
Rating : 5

Great service. Swift attention and precise estimate on the phone. The quote occurred to be more difficult and broad than anticipated but the job has been accomplished to overall satisfaction at a feasible cost.

Christopher Rogers
Rating : 5

I have used Priory several times. I have received my quote upfront and time keeping has been brilliant. Each plumber was very polite and has left the area neat and tidy after work. I would easily recommend Priory Gas Heating…

Sandra Howell
Rating : 5

After a complete failure of our heating system we received a range of quotes for a replacement heating and hot water system. Not being an expert in the area of heating I commission a heating engineer to validate all the quotes.…

Mick Elliott
Rating : 5
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