Unvented Cylinder

One of the types of hot water cylinder fitted today is one called an unvented cylinder. Below is a description of an unvented hot water cylinder and a couple of facts that are handy to know:The water that is stored in an unvented is at around 3bar which is in real terms equivalent to 3 times that of our own atmospheric pressure, and is judged to be safe. The interesting part is when the water starts to heat up. Normally water will start to boil at 100 C. Now if the water is being stored under pressure, for example 3bar, it will not begin to boil until about 132 C. This doesn’t sound much of a problem that is until the cylinder or vessel develops a crack. Should this happen the water that was a liquid at 3bar pressure immediately becomes steam at 1bar of pressure. Once again this does seem too bad, until you learn that steam requires a container 1600 times larger than the one it is sat in at the moment. The result is a massive explosion. Chessington Plumbers can identify and service an unvented cylinder. Stop this happening: An unvented cylinder comes with some safety devices, if one fails, another cuts in, if this fails, yet another cuts in. The problem is that these devices are only safe if they have been installed professionally and had regular servicing. For this reason the homeowner needs to stay well clear of them. A Chessington Plumber will be able to fit and inspect these safety devices.If you do have an unvented cylinder you should call for a G3-qualified plumber to service it every year. In the interim, keep an eye on it yourself. If you ever see water dripping running out of the pipes connected to the cylinder, call the G3-qualified plumber immediately to check it out.

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