If you live in a larger property or have a ‘busy’ household, unvented hot-water is generally the most appropriate system. If sufficient mains water supply is available, an unvented system can produce very impressive hot water flow rates allowing rapid bath fill and powering luxury showering systems.
In addition to potentially high-flow rates at mains pressure other advantages are that no additional tanks are required and the cylinder itself can be positioned in any suitable location. An immersion heater can be used to heat the water as a backup so there is less reliance on the boiler. Other than an initially higher installation cost, it is almost the perfect system.
The cylinders themselves are somewhat different from the traditional thin gauge copper cylinders. Modern cylinders are almost invariably made from duplex stainless steel, which combines the strength with corrosion resistance. This allows for a relatively lightweight product that is massively strong and highly resistant to corrosion. The cylinders are, by law, provided with all the operational and safety devices required for a complete installation.
It is strongly recommended by the manufacturer’s and governing bodies that unvented systems are serviced annually, this ensures that the safety devices and other aspects of the system are checked for correct operation. The discharge pipe from the safety devices may sometimes drip, this indicates the cylinder requires attention from a qualified engineer.
Though inherently safe due to the multi-tiered safety devices, unvented cylinders have an explosive potential. For this reason it is a legal requirement that anyone installing or working on unvented cylinders has been trained and approved under the scope of section G3 of the Building Regulations. By process of training and assessment we are competent and entitled to work on unvented systems.