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London Plumbers Call for Unvented Hot Water Cylinders

What seems like a basic water heating system in many countries around the world is finally catching up in London and the rest of the UK. Pressurised hot water cylinders and central heating systems provide hot water at mains pressure level. Unvented systems recently installed in London eliminate cases where two users cannot draw hot water simultaneously, for example when one member of the household having a shower while another tries to do the washing up. Unvented systems use the pressure of the mains infrastructure to retain sufficient pressure of hot water around the entire house. This is in stark contrast to the traditional gravity fed systems with a feeder tank normally positioned in the loft, offering low pressure in the top floors, due to lack of head for the hot water to build up pressure.

With many houses in London and the home counties now boasting two or more bathrooms, along with an impressive array of systems that use hot water (Jacuzzi, jet shower), users do not accept a system that cannot cope with the hot water demands of modern life. With long working hours, time in the home is valuable and people these days do not want to wait for the hot water, nor do they accept a trickle form the hot water shower. An unvented cylinder and central heating system is the answer, providing virtually unlimited volume of hot water, in a convenient pressure for the shower or any other domestic use.

There are three main groups of materials that are used in the manufacturing of unvented cylinders. Each of these has their respective advantages and disadvantages. The three types of materials are copper, Stainless Steel and sheet metal.

* Copper cylinders - the lightest material, and used to be relatively cheap until the recent sharp increase of the commodity prices of copper. Still they are very popular in the UK, despite having the lowest heat retention properties of the three.

* Stainless Steel tanks - the most expensive of the three, offering longer lifetime, but at a price. They have good heat retention, and only a little heavier than copper tanks

* Sheet metal cylinders - the most popular type in most European countries and the cheapest of the three. Inner enamel glazing ensures virtually no build up of scale. They provide the highest heat retention performance of the three, but also are the heaviest.

Before choosing and making your purchasing decision, it is important to keep in mind several points regarding your unvented cylinder:

* Volume and external dimensions - a typical household (4-5 people) in the UK will require a 200 liter cylinder. However, the cylinders come in different shapes and dimensions. Make sure to check the width and height of the cylinder, so that it fits in the airing cupboard (or any other space you plan to position the tank in).

* Heat retention - since the hot water cylinder is primarily there to store the hot water, it is important to check what insulation it has. The thicker the insulation the better heat retention it will have and less heat would be lost during the day. For reference, good cylinders lose less than 3 kW per 24 hours.

* Manufacturers service and warranty - although unvented tanks have good record of reliability (they have virtually no moving parts), it is important to note what warranty and service level is provided by the manufacturer.


Heating + Plumbing Central is dedicated to the introduction of high efficiency central heating systems in London. The company’s London plumbers focus on energy efficiency boilers in London, with each London Plumber bringing in years of London boiler repairs and London boiler installations experience. Our plumbers in London are all local to their area and are dedicated to their community.

This page has been written with contributions from plumbers from Oxfordshire and plumbing and heating engineers from Watford. Several of the company's experienced plumbers from Middlesex have worked on similar issues as well as some of our qualified plumbers from Marylebone and our Holland Park heating engineers.