| Unvented hot water systems are finally growing | | | | used to be relatively cheap until the recent sharp |
| in popularity in the UK, which is still mostly reliant | | | | increase of the commodity prices of copper. Still |
| on gravity fed systems throughout the housing | | | | they are very popular in the UK, despite having |
| stock. This system which has its roots in the | | | | the lowest heat retention properties of the three. |
| nineteenth century, suffers from low pressure of | | | | * Stainless Steel tanks - the most expensive of |
| hot water (especially in the top floors), and limited | | | | the three, offering longer lifetime, but at a price. |
| availability of hot water to more than one user. It | | | | They have good heat retention, and only a little |
| is common for one user to have a shower, only | | | | heavier than copper tanks. |
| to be surprised by a splash of cold water as soon | | | | * Sheet metal shell - offers the best heat |
| as another household member turns on the hot | | | | retention properties, and is cheapest of the three |
| water tap elsewhere in the house. Compare this | | | | technologies. Although heaviest of the three, |
| with a steady pressure (equal to the mains | | | | sheet metal shells are highly popular in the rest of |
| pressure of the cold water) all around the house | | | | Europe and normally come with an inner enamel |
| even if more than one tap is used at any point in | | | | glazing, thus reducing build up of scale. |
| time. | | | | Before choosing and making your purchasing |
| Hectic lifestyles mean high demand from the basic | | | | decision, it is important to keep in mind several |
| systems in the home. These days we do not | | | | points regarding your unvented cylinder: |
| expect to wait for hot water, nor do we expect | | | | * Volume and external dimensions - a typical |
| to get hit by a cold flush of water in the shower | | | | household (4-5 people) in the UK will require a 200 |
| when someone else turns on the hot water tap in | | | | liter cylinder. However, the cylinders come in |
| the house. Furthermore, many modern houses | | | | different shapes and dimensions. Make sure to |
| have two bathrooms, as well as a host of other | | | | check the width and height of the cylinder, so |
| appliances that put pressure on the hot water | | | | that it fits in the airing cupboard (or any other |
| systems, such as a whirlpool bath or a jet | | | | space you plan to position the tank in). |
| shower. Only unvented systems can offer the | | | | * Heat retention performance - since the main |
| reliable supply of hot water in the right quantity | | | | purpose of a hot water tank is to retain the |
| and pressure to allow for all this to work | | | | water inside hot, it is important to check the heat |
| seamlessly. | | | | loss score of the tank. A good tank loses less |
| Most unvented cylinders are manufactured from | | | | than 3 kW per 24 hours). |
| metals that fall into one of three categories: | | | | * Warranty and after-service - unvented hot |
| copper, stainless steel and glazed sheet metal. | | | | water cylinders have good record of long life and |
| Each one of these technologies is highly effective | | | | little in the way of faults. Nevertheless it is |
| and used throughout the world. | | | | important to check what warranty and service |
| * Copper cylinders - the lightest material, and | | | | you get from the manufacturer. |